ORCID Profile
0000-0002-5086-4865
Current Organisations
University of Birmingham
,
Monash University
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Psychology | Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology) | Road Transportation and Freight Services | Laboratory Phonetics and Speech Science | Environmental and Occupational Health and Safety | Sensory Processes, Perception and Performance | Pattern Recognition and Data Mining | Psychological Methodology, Design and Analysis | Computer-Human Interaction | Developmental Psychology and Ageing
Expanding Knowledge in Psychology and Cognitive Sciences | Expanding Knowledge in Technology | Road Safety | Behaviour and Health | Automotive Equipment | Evaluation of Health Outcomes | Expanding Knowledge in the Biological Sciences | Health Status (e.g. Indicators of Well-Being) | Hearing, Vision, Speech and Their Disorders | Expanding Knowledge in the Medical and Health Sciences |
Publisher: Wiley
Date: 25-10-2018
DOI: 10.1113/JP275917
Publisher: Elsevier BV
Date: 06-2007
DOI: 10.1016/J.NEULET.2007.05.027
Abstract: Mobile phones signals are pulse-modulated microwaves, and EEG studies suggest that the extremely low-frequency (ELF) pulse modulation has sleep effects. However, 'talk', 'listen' and 'standby' modes differ in the ELF (2, 8, and 217Hz) spectral components and specific absorption rates, but no sleep study has differentiated these modes. We used a GSM900 mobile phone controlled by a base-station simulator and a test SIM card to simulate these three specific modes, transmitted at 12.5% (23dBm) of maximum power. At weekly intervals, 10 healthy young adults, sleep restricted to 6h, were randomly and single-blind exposed to one of: talk, listen, standby and sham (nil signal) modes, for 30 min, at 13:30 h, whilst lying in a sound-proof, lit bedroom, with a thermally insulated silent phone beside the right ear. Bipolar EEGs were recorded continuously, and subjective ratings of sleepiness obtained every 3 min (before, during and after exposure). After exposure the phone and base-station were switched off, the bedroom darkened, and a 90 min sleep opportunity followed. We report on sleep onset using: (i) visually scored latency to onset of stage 2 sleep, (ii) EEG power spectral analysis. There was no condition effect for subjective sleepiness. Post-exposure, sleep latency after talk mode was markedly and significantly delayed beyond listen and sham modes. This condition effect over time was also quite evident in 1-4Hz EEG frontal power, which is a frequency range particularly sensitive to sleep onset. It is possible that 2, 8, 217Hz modulation may differentially affect sleep onset.
Publisher: Oxford University Press (OUP)
Date: 08-2012
DOI: 10.5665/SLEEP.2004
Publisher: Wiley
Date: 06-2013
DOI: 10.1111/IMJ.12159
Abstract: Currently, the National Transport Commission is considering four options to form the regulatory framework for rail safety within Australia with respect to fatigue. While the National Transport Commission currently recommends no limitations around hours of work or rest, we provide evidence which suggests regulatory frameworks should incorporate a traditional hours of service regulation over more flexible policies. Our review highlights: Shift durations >12 h are associated with a doubling of risk for accident and injury. Fatigue builds cumulatively with each successive shift where rest in between is inadequate (<12 h). A regulatory framework for fatigue management within the rail industry should prescribe limits on hours of work and rest, including maximum shift duration and successive number of shifts. Appropriately, validated biomathematical models and technologies may be used as a part of a fatigue management system, to augment the protection afforded by limits on hours of work and rest. A comprehensive sleep disorder screening and management programme should form an essential component of any regulatory framework.
Publisher: Oxford University Press (OUP)
Date: 06-11-2020
DOI: 10.1093/SLEEP/ZSZ197
Abstract: As slow-wave activity (SWA) is critical for cognition, SWA-enhancing technologies provide an exciting opportunity to improve cognitive function. We focus on improving cognitive function beyond sleep-dependent memory consolidation, using an automated device, and in middle-aged adults, who have depleted SWA yet a critical need for maximal cognitive capacity in work environments. Twenty-four healthy adult males aged 35–48 years participated in a randomized, double-blind, cross-over study. Participants wore an automated acoustic stimulation device that monitored real-time sleep EEG. Following an adaptation night, participants were exposed to either acoustic tones delivered on the up phase of the slow-wave (STIM) or inaudible “tones” during equivalent periods of stimulation (SHAM). An executive function test battery was administered after the experimental night. STIM resulted in an increase in delta (0.5–4 Hz) activity across the full-night spectra, with enhancement being maximal at 1 Hz. SWA was higher for STIM relative to SHAM. Although no group differences were observed in any cognitive outcomes, due to large in idual differences in SWA enhancement, higher SWA responders showed significantly improved verbal fluency and working memory compared with nonresponders. Significant positive associations were found between SWA enhancement and improvement in these executive function outcomes. Our study suggests that (1) an automated acoustic device enhances SWA (2) SWA enhancement improves executive function (3) SWA enhancement in middle-aged men may be an important therapeutic target for enhancing cognitive function and (4) there is a need to examine interin idual responses to acoustic stimulation and its effect on subsequent cognitive function. This study has been registered with the Australian New Zealand Clinical Trials Registry. “The efficacy of acoustic tones in slow-wave sleep enhancement and cognitive function in healthy adult males”. www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=371548& isReview=true ACTRN12617000399392.
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.SLEEP.2019.01.012
Abstract: In the months after childbirth, women are vulnerable to sleep disturbances and sleep-related deficits in functioning, such as fatigue, daytime sleepiness, and attentional lapses. Currently there is limited evidence that these deficits are modifiable. Using both self-report and objective measures, this study examined changes in sleep-related daytime functioning among women attending a residential early parenting program for assistance with unsettled infant behavior and mild to moderate postpartum distress. Participants were 78 women (age M = 34.16, SD = 4.16 years) attending a five-day program with their infants (age M = 8.67, SD = 4.82 months). Sleep was assessed via self-report. Sleep-related daytime functioning was operationalized as fatigue, sleepiness, and sustained attention, and measured using validated questionnaires (all women) and the 10-min visual Psychomotor Vigilance Test (PVT subgroup of 47 women). All measures were administered on both admission (baseline) and discharge. On admission, participants reported elevated sleep disturbance (94%), fatigue (91%), as well as trait (54%) and state (67%) sleepiness. From admission to discharge, there were medium effect size reductions in fatigue and sleepiness, and large effect size improvements in sleep quality related domains such as increased sleep efficiency and reduced nighttime awakenings (all p < 0.001) changes in total sleep time were nonsignificant (p = 0.22). PVT reciprocal mean reaction times were also significantly faster (p = 0.001 medium effect size). This study demonstrated that among women attending a brief residential early parenting program, fatigue, daytime sleepiness, and objectively measured psychomotor vigilance can be improved. Implications for further research and potential treatments are discussed.
Publisher: Oxford University Press (OUP)
Date: 04-2006
Abstract: Although sleepiness appears to heighten distraction from the task at hand, especially if the latter is dull and monotonous, this aspect of sleep loss has not been assessed in any systematic way. Distractions are a potential cause of performance lapses (as are micro-sleeps). Here, we investigate the effects of sleepiness on a monotonous task, with and without distraction. Repeated Measures 2 x 2 counterbalanced design, comprising Sleepiness (night sleep restricted to 5 hours x normal sleep) and Distraction (distraction x no distraction). Participants underwent 30-minute sessions on the Psychomotor Vigilance Test (2:00 PM - 3:10 PM), with or without an attractive distraction to be ignored, under normal and sleep-restricted conditions. Sixteen healthy young adults (mean age 21.10 years 21-25 years [8 men 8 women]) without any sleep or medical problems and without any indication of daytime sleepiness. Normal sleep versus sleep restricted to 5 hours and distraction versus no distraction. Distraction comprised a television in the visual periphery, showing an attractive video that had to be ignored. Psychomotor Vigilance Test performance was monitored, as were the participants' head turns toward the television via videocameras. There was a significant increase in both head turns and lapses during sleep restriction plus distraction. Moreover, sleepiness also increased head turns even during no distraction. Distracting effects of sleepiness were clearly evident during the initial 10 minutes of testing. Distractibility is an important aspect of sleepiness, which has relevance to safety in the real world, eg, sleepy driving.
Publisher: Springer Science and Business Media LLC
Date: 29-04-2020
DOI: 10.1038/S41598-020-63144-Y
Abstract: In a visually stimulating environment with competing stimuli, we continually choose where to allocate attention, and what to ignore. Wake and circadian-dependent modulation of attentional control and resolution of conflict is poorly understood. Twenty-two participants (17males 25.6 ± 5.6 years) completed ocular motor tasks throughout 40 hours of sleep deprivation under constant routine conditions. A prosaccade task required a reflexive saccade toward a stimulus (no conflict), while an antisaccade task required inhibiting a reflexive saccade to the peripheral stimulus, and looking in the mirror opposite instead (conflict resolution). Antisaccade inhibitory errors showed circadian modulation, being highest in the morning, progressively decreasing until melatonin onset, before returning to the prior morning’s peak throughout the biological night. This diurnal rhythm was blunted by sleep loss ( hours), with inhibitory control remaining impaired across the second biological day. For prosaccade, responses slowed down during the biological night. Taken together, we provide evidence for a circadian modulation of attentional bias: the morning being biased toward reflexive responding, and the evening toward higher inhibitory control. Our data show that sleep loss and circadian timing differentially impact attention, depending on whether a response conflict is present (antisaccade) or absent (prosaccade).
Publisher: Oxford University Press (OUP)
Date: 18-01-2018
DOI: 10.1093/SLEEP/ZSX213
Abstract: Working memory (WM) has been described as a multicomponent process, comprised of the following: attention-driven encoding, maintenance and rehearsal of information, and encoding to and retrieval from episodic memory. Impairments can affect higher-order cognitive processes and many everyday functions. The impact of sleep changes on these cognitive processes across the life span needs to be investigated. The aim of the current study is to examine the effects of sleep deprivation on component processes of WM, comparing younger and older adults across verbal and visuospatial modalities. Thirty-one younger adults (19-38 years) and 33 older adults (59-82 years) attended two counterbalanced sleep protocols: a regular night of sleep followed by testing the next day (normally rested condition), and 36 hr of total sleep deprivation (TSD), followed by testing (TSD condition). Participants completed matched versions of verbal and visuospatial WM tasks across conditions. Younger adults significantly outperformed older adults on encoding and displacement component processes, for both verbal and visuospatial WM. Following TSD, younger adults showed a significantly larger drop compared with older adults in verbal encoding and in visuospatial displacement. A main effect of condition was observed for verbal displacement. Differences were observed in the performance of younger and older adults on component processes of WM following TSD. This suggests that TSD can have differential effects on each component process when younger and older adults are compared, in both verbal and visuospatial tasks. Understanding this profile of changes is important for the development of possible compensatory strategies or interventions and the differentiation of clinical and healthy populations.
Publisher: Oxford University Press (OUP)
Date: 29-08-2018
DOI: 10.1093/SLEEP/ZSY148
Abstract: The interaction between homeostatic sleep pressure and circadian timing modulates the impact of sleep deprivation on cognition. We aimed to investigate how this interaction affects different cognitive functions. Twenty-three healthy volunteers (18 males mean age = 25.4 ± 5.7 years) underwent 40 hours of sleep deprivation under constant routine conditions. Performance on the Psychomotor Vigilance Test and a cognitive battery assessing vigilant attention, complex attention, recognition memory, and working memory was assessed in the morning (27 hours awake) and evening (37 hours awake) during sleep deprivation and compared to well-rested performance 24 hours earlier. Circadian phase assessments confirmed evening tests occurred in the wake maintenance zone (WMZ). Increased time awake significantly impacted performance on all measures except recognition memory. Post hoc analyses found performance on all measures was significantly impaired in the morning following 27 hours of sleep deprivation compared to well-rested performance 24 hours earlier. In contrast, complex attention and working memory were preserved in the WMZ after 37 hours awake compared to 24 hours earlier, while vigilant attention and PVT performance were significantly impaired. During sleep deprivation, composite scores of speed and accuracy were both impaired in the morning, while only speed was impaired during the WMZ. We observed task- and time-dependent effects of sleep deprivation, such that vigilant attention was significantly impaired after both 27 hours and 37 hours awake (compared to when well-rested at the same circadian clock time). In contrast, complex attention and working memory were impaired at 27 hours awake, but preserved in the WMZ despite increased homeostatic sleep pressure (37 hours awake).
Publisher: Wiley
Date: 18-07-2017
DOI: 10.1002/HUP.2626
Abstract: Epidemiological and laboratory-based driving simulator studies have shown the detrimental impact of moderate, legal levels of alcohol consumption on driving performance in sleepy drivers. As less is known about the time course of decaying alcohol alongside performance impairment, our study examined impairment and recovery of performance alongside decaying levels of alcohol, with and without sleep restriction. Sixteen healthy young males (18-27 years) underwent 4 counterbalanced conditions: Baseline, Alcohol (breath alcohol concentration [BrAC] < 0.05%), Sleep Restriction (5 hr time in bed), and Combined. Participants consumed alcohol (or control drink) ~4.5 hr post wake (12:30 p.m.). To test on the descending limb of alcohol, attention and vigilance test batteries commenced 1 hr after consumption and were completed every 30 min for 2 hr (1:30 p.m.-3:30 p.m.). The Combined condition impaired subjective and objective sleepiness. Here, performance deficits peaked 90 min after alcohol consumption or 30 min after the BrAC peak. Performance did not return to baseline levels until 2.5 hr following consumption, despite receiving rest breaks in between testing. These findings suggest that (a) falling BrACs are an inadequate guide for performance/safety and (b) rest breaks without sleep are not a safety measure for mitigating performance impairment when consuming alcohol following restricted sleep.
Publisher: Wiley
Date: 14-06-2004
DOI: 10.1002/HBM.20052
Publisher: American Academy of Sleep Medicine (AASM)
Date: 15-05-2014
DOI: 10.5664/JCSM.3692
Publisher: Wiley
Date: 20-11-2017
DOI: 10.1111/JSR.12633
Abstract: We aimed to investigate whether self-monitoring of performance is altered during 60 h of total sleep deprivation, following 2 nights of recovery sleep, and by task difficulty and/or subjective sleepiness. Forty adults (22 females, aged 19-39 years) underwent a 5-day protocol, with a well-rested day, 66 h total sleep deprivation (last test session at 60 h), and 2 nights of 8 h recovery sleep. An arithmetic task (MATH) with three difficulty levels assessed working memory. The Psychomotor Vigilance Task assessed sustained attention. Arithmetic accuracy and Psychomotor Vigilance Task median reaction time measured objective performance. Subjective performance was measured with self-reported accuracy and speed. Objective-subjective differences assessed self-monitoring ability. The performance on both tasks declined during total sleep deprivation and improved following recovery. During total sleep deprivation, participants accurately self-monitored performance on the Psychomotor Vigilance Task however, they overestimated cognitive deficits on MATH, self-reporting performance as worse than actually observed. Following recovery, participants overestimated the extent of performance improvement on the Psychomotor Vigilance Task. Task difficulty influenced self-monitoring ability, with greater overestimation of performance deficits during total sleep deprivation as difficulty increased. Subjective sleepiness predicted subjective performance ratings at several time points, only for the Psychomotor Vigilance Task. The ability to self-monitor performance was impaired during total sleep deprivation for working memory and after recovery sleep for the Psychomotor Vigilance Task, but was otherwise accurate. The development of self-monitoring strategies, assessing both subjective perceptions of performance and subjective sleepiness, within operational contexts may help reduce the consequences of sleep-related impairments.
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.SLEEP.2007.02.006
Abstract: The sleep literature increasingly points to an apparent chronic sleep debt in the general population. We investigated this by examining perceived shortfalls in daily sleep, using more indirect questioning methods. To determine perceived sleep deficits, 10,810 adults completed a simple questionnaire, which avoided leading questions and provided information on sleep length, daytime sleepiness, desired sleep length, a choice of attractive daytime activities in a "free hour", and "stressful lifestyle". From this we assessed whether deficits were reflected by increased daytime sleepiness or opting for more sleep when given attractive waking alternatives. Respondents were ided according to age and sex. Half of men and women seemed to desire more sleep, but this apparent sleep deficit was not correlated with daytime sleepiness, for any age or sex group. Irrespective of deficit, few people opted for sleep when given waking alternatives. "Stressful lifestyle" was independently related to this sleep deficit. Desiring more sleep may also be synonymous with a need for more "time out", as sleep deficit was unrelated to daytime sleepiness but rather related to "stressful lifestyle." Extra sleep may not be the only anodyne for sleep deficit.
Publisher: Elsevier BV
Date: 11-2019
Publisher: Wiley
Date: 25-05-2021
DOI: 10.1111/PSYP.13839
Abstract: We systematically examined the temporal relationships between subjective sleepiness and both physiological drowsiness and performance impairment in a controlled laboratory setting. Eighteen healthy young adults (8 women M AGE = 21.44 ± 3.24 years) underwent 40 hr of extended wakefulness, completing a bihourly Karolinska Sleepiness Scale (KSS) and 10‐min Psychomotor Vigilance Task (PVT). Microsleeps and slow eye movements (SEMs) were scored during the PVT. KSS scores increased 3 hr prior to performance impairment ( p .001) and 4–6 hr prior to physiological sleepiness ( p .001). There were strong within‐subject correlations between KSS and PVT lapses ( r = 0.75, p .001) and physiological drowsiness ( r 0.60, p .001). Between‐subjects product‐moment correlations were more modest but showed a significant positive increase across time awake, suggesting that subjective sleepiness and objective outcomes were more tightly correlated after sleep loss. Cross‐correlations showed significant positive correlations at 0‐lag ( p .034) however, a high proportion of participants showed maximal correlations at positive lags, suggesting KSS was associated with future objective impairment. Within in iduals, subjective sleepiness was highly correlated with objective impairment, between‐subject correlations were more modest, possibly due to interin idual vulnerability to sleep loss. These results suggest that subjective sleepiness represents an inbuilt early warning system for subsequent drowsiness and performance impairment.
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.PHYSBEH.2008.11.009
Abstract: Seemingly, many healthy adults have accrued a sleep debt, as determined by findings based on the multiple sleep latency test (MSLT). However, our recent, extensive survey found self-reported sleep deficit was not linked to daytime sleepiness determined by the Epworth sleepiness scale (ESS). Here, we report on the link between self-reported sleep deficit and gold standard measures of sleepiness: MSLT, Psychomotor vigilance test (PVT) and Karolinska Sleepiness Scale (KSS). Habitual sleep time in forty-three participants, from using a week long sleep diary and actiwatch data, compared with self-ratings of how much sleep they needed, provided estimates of apparent sleep deficit or otherwise. They were split into categories: 'sleep deficit' (Av. -47 min), 'sleep plus' (Av. 47 min) or 'neutral' (Av. 0+/-15 min), depicting perceived shortfall (or excess) sleep. Although the deficit group desired to sleep longer than the other groups, they actually obtained similar habitual nightly sleep as the neutral group, but less than the sleep plus group. 'Survival curves' based on those falling asleep during the MSLT showed no difference between the groups. Neither was there any difference between the groups for the PVT, KSS, or ESS. Here, factors other than sleepiness seem to influence self-perceived sleep deficits.
Publisher: SAGE Publications
Date: 12-2013
Abstract: The current study characterized the temporal dynamics of ocular indicators of sleepiness during extended sleep restriction. Ten male participants (mean age ± SD = 23.3 ± 1.6 years) underwent 40 h of continuous wakefulness under constant routine (CR) conditions they completed the Karolinska Sleepiness Scale (KSS) and a 10-min auditory psychomotor vigilance task (aPVT) hourly. Waking electroencephalography (EEG) and ocular measures were recorded continuously throughout the CR. Infrared-reflectance oculography was used to collect the ocular measures positive and negative litude-velocity ratio, mean blink duration, the percentage of eye closure, and a composite score of sleepiness levels (Johns Drowsiness Scale). All ocular measures, except blink duration, displayed homeostatic and circadian properties. Only circadian effects were detected in blink duration. Significant, phase-locked cross-correlations ( p 0.05 ) were detected between ocular measures and aPVT reaction time (RT), aPVT lapses, KSS, and EEG delta-theta (0.5-5.5 Hz), theta-alpha (5.0-9.0 Hz), and beta (13.0-20.0 Hz) activity. Receiver operating characteristic curve analysis demonstrated reasonable sensitivity and specificity of ocular measures in correctly classifying aPVT lapses above in idual baseline thresholds (initial 16 h of wakefulness). Under conditions of sleep restriction, ocular indicators of sleepiness paralleled performance impairment and self-rated sleepiness levels, and demonstrated their potential to detect sleepiness-related attentional lapses. These findings, if reproduced in a larger s le, will have implications for the use of ocular-based sleepiness-warning systems in operational settings.
Publisher: Oxford University Press (OUP)
Date: 05-2015
DOI: 10.5665/SLEEP.4672
Publisher: Springer Science and Business Media LLC
Date: 29-03-2019
DOI: 10.1038/S41598-019-41712-1
Abstract: The PERIOD2 ( PER2 ) gene is a core molecular component of the circadian clock and plays an important role in the generation and maintenance of daily rhythms. Rs35333999, a missense variant of PER2 common in European populations, has been shown to associate with later chronotype. Chronotype relates to the timing of biological and behavioral activities, including when we sleep, eat, and exercise, and later chronotype is associated with longer intrinsic circadian period (cycle length), a fundamental property of the circadian system. Thus, we tested whether this PER2 variant was associated with circadian period and found significant associations with longer intrinsic circadian period as measured under forced desynchrony protocols, the ‘gold standard’ for intrinsic circadian period assessment. Minor allele (T) carriers exhibited significantly longer circadian periods when determinations were based on either core body temperature or plasma melatonin measurements, as compared to non-carriers (by 12 and 11 min, respectively accounting for ~7% of inter-in idual variance). These findings provide a possible underlying biological mechanism for inter-in idual differences in chronotype, and support the central role of PER2 in the human circadian timing system.
Publisher: Elsevier BV
Date: 2013
Publisher: Wiley
Date: 28-11-2008
DOI: 10.1111/J.1365-2869.2008.00680.X
Abstract: Though extended night-time sleep mostly reduces the 'afternoon dip', little is known about evening benefits to alertness, or about comparisons with an afternoon nap or caffeine. Twenty healthy carefully screened adults, normal waking alertness levels, underwent four counterbalanced conditions: usual night sleep night sleep extended<90 min (usual bed-time) up to 20 min afternoon nap and 150 mg afternoon caffeine (versus decaffeinated coffee). Sleepiness was measured by afternoon and evening multiple sleep latency test (MSLTs), longer psychomotor vigilance test (PVT) sessions and a subjective sleepiness scale. Sleep was extended by average of 74 min, and all participants could nap 15-20 min. Sleep extension had little effect on PVT determined modest levels of morning sleepiness. Afternoon and evening MSLTs showed all active treatments significantly reduced the 'dip', with nap most effective until mid-evening next effective was caffeine, then extension. Late evening sleepiness and subsequent sleep did not differ between conditions. Arguably, participants may have experienced some 'sleep debt', given they extended sleep and reflected some sleepiness within settings sensitive to sleepiness. Nevertheless, extended sleep seemed largely superfluous and inefficient in reducing modest levels of sleepiness when compared with a timely nap, and even caffeine. Sleep, such as food and fluid intakes, can be taken to excess of real biological needs, and for many healthy adults, there is a level of modest daytime sleepiness, only unmasked by very sensitive laboratory measures. It may reflect a requirement for more sleep or simply be within the bounds of normal acceptability.
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.BBR.2012.04.050
Abstract: Sleep disturbance in neurological and psychiatric disorders is common and associated with diminished cognitive functioning. Whilst these deficits can be localised predominantly to frontal and parietal regions, there have been reported inconsistencies which may be due to differences in the difficulty and type of task. In the present study we examined the effects of sleep deprivation (SD) whilst parametrically varying working memory load using an n-back task. 20 right-handed males performed the n-back task after a night of normal sleep (RW: rested wakefulness) and after approximately 31 h of SD. Comparison of load responsive cerebral activation identified two clusters where the parametric response was altered after SD. In the right ventrolateral prefrontal cortex activity was reduced at the most difficult working memory load, whereas in the right inferior parietal lobe activity was increased at the simplest working memory load. The strength of activation in both of these regions during RW predicted the response of those same regions to SD. While the ability to predict signal change has previously been demonstrated using behavioural measures, to our knowledge this is the first study to show that the neuronal effects of SD can be predicted based upon activation during a normal rested condition.
Publisher: Wiley
Date: 18-03-2021
DOI: 10.1111/JSR.13312
Abstract: We aimed to investigate the impact of the Wake Maintenance Zone (WMZ) on measures of drowsiness, attention, and subjective performance under rested and sleep deprived conditions. We studied 23 healthy young adults (18 males mean age = 25.41 ± 5.73 years) during 40 hr of total sleep deprivation under constant routine conditions. Participants completed assessments of physiological drowsiness (EEG‐scored slow eye movements and microsleeps), sustained attention (PVT), and subjective task demands every two hours, and four‐hourly ocular motor assessment of inhibitory control (inhibition of reflexive saccades on an anti‐saccade task). Tests were analyzed relative to dim light melatonin onset (DLMO) the WMZ was defined as the 3 hr prior to DLMO, and the preceding 3 hr window was deemed the pre‐WMZ. The WMZ did not mitigate the adverse impact of ~37 hr sleep deprivation on drowsiness, sustained attention, response inhibition, and self‐rated concentration and difficulty, relative to rested WMZ performance (~13 hr of wakefulness). Compared to the pre‐WMZ, though, the WMZ improved measures of sustained attention, and subjective concentration and task difficulty, during sleep deprivation. Cumulatively, these results expand on previous work by characterizing the beneficial effects of the WMZ on operationally‐relevant indices of drowsiness, inhibitory attention control, and self‐rated concentration and task difficulty relative to the pre‐WMZ during sleep deprivation. These results may inform scheduling safety‐critical tasks at more optimal circadian times to improve workplace performance and safety.
Publisher: Springer Science and Business Media LLC
Date: 29-07-2019
DOI: 10.1038/S41598-019-47311-4
Abstract: A neural network model was previously developed to predict melatonin rhythms accurately from blue light and skin temperature recordings in in iduals on a fixed sleep schedule. This study aimed to test the generalizability of the model to other sleep schedules, including rotating shift work. Ambulatory wrist blue light irradiance and skin temperature data were collected in 16 healthy in iduals on fixed and habitual sleep schedules, and 28 rotating shift workers. Artificial neural network models were trained to predict the circadian rhythm of (i) salivary melatonin on a fixed sleep schedule (ii) urinary aMT6s on both fixed and habitual sleep schedules, including shift workers on a diurnal schedule and (iii) urinary aMT6s in rotating shift workers on a night shift schedule. To determine predicted circadian phase, center of gravity of the fitted bimodal skewed baseline cosine curve was used for melatonin, and acrophase of the cosine curve for aMT6s. On a fixed sleep schedule, the model predicted melatonin phase to within ± 1 hour in 67% and ± 1.5 hours in 100% of participants, with mean absolute error of 41 ± 32 minutes. On diurnal schedules, including shift workers, the model predicted aMT6s acrophase to within ± 1 hour in 66% and ± 2 hours in 87% of participants, with mean absolute error of 63 ± 67 minutes. On night shift schedules, the model predicted aMT6s acrophase to within ± 1 hour in 42% and ± 2 hours in 53% of participants, with mean absolute error of 143 ± 155 minutes. Prediction accuracy was similar when using either 1 (wrist) or 11 skin temperature sensor inputs. These findings demonstrate that the model can predict circadian timing to within ± 2 hours for the vast majority of in iduals on diurnal schedules, using blue light and a single temperature sensor. However, this approach did not generalize to night shift conditions.
Publisher: Informa UK Limited
Date: 18-04-2016
Publisher: Oxford University Press (OUP)
Date: 22-02-2019
DOI: 10.1093/SLEEP/ZSZ041
Publisher: Scandinavian Journal of Work, Environment and Health
Date: 20-02-2015
DOI: 10.5271/SJWEH.3486
Abstract: Shift workers are prone to obesity and associated co-morbidities such as diabetes and cardiovascular disease. Sleep restriction associated with shift work results in dramatic endocrine and metabolic effects that predispose shift workers to these adverse health consequences. While sleep restriction has been associated with increased caloric intake, food preference may also play a key role in weight gain associated with shift work. This study examined the impact of an overnight simulated night shift on food preference. Sixteen participants [mean 20.1, standard deviation (SD) 1.4 years 8 women] underwent a simulated night shift and control condition in a counterbalanced order. On the following morning, participants were provided an opportunity for breakfast that included high- and low-fat food options (mean 64.8% and 6.4% fat, respectively). Participants ate significantly more high-fat breakfast items after the simulated night shift than after the control condition [167.3, standard error of the mean (SEM 28.7) g versus 211.4 (SEM 35.6) g P=0.012]. The preference for high-fat food was apparent among the majority of in iduals following the simulated night shift (81%), but not for the control condition (31%). Shift work and control conditions did not differ, however, in the total amount of food or calories consumed. A simulated night shift leads to preference for high-fat food during a subsequent breakfast opportunity. These results suggest that food choice may contribute to weight-related chronic health problems commonly seen among night shift workers.
Publisher: Springer Science and Business Media LLC
Date: 29-01-2019
Publisher: Wiley
Date: 2006
DOI: 10.1002/HUP.769
Abstract: Although the ingestion of high levels of glucose might have a short acting alerting effect, there is evidence of an ensuing enhancement of sleepiness in people already sleepy. Some 'energy drinks' contain large quantity of sugars. We compared 250 ml of a well known 'energy drink' (42 g sugars, containing a low [30 mg] level of caffeine for 'flavouring') with a nil sugar nil caffeine, similar tasting control. These were given a week apart, in a repeated measures, double blind, balanced design, to 10 participants sleep restricted to 5 h the prior night. They had a light lunch, consumed a drink at 13:50 h, and 10 min later underwent 3 x 30 min consecutive periods at a reaction time (RT) task (the Psychomotor Vigilance Test), separated by 3 min breaks when self-ratings of sleepiness were made. The energy drink did not counteract sleepiness, and led to slower RTs and more lapses during the final 30 min session, around 80 min after consumption.
Publisher: Scandinavian Journal of Work, Environment and Health
Date: 09-04-2016
DOI: 10.5271/SJWEH.3560
Abstract: This study aimed to investigate sleep and circadian phase in the relationships between neurobehavioral performance and the number of consecutive shifts worked. Thirty-four shift workers [20 men, mean age 31.8 (SD 10.9) years] worked 2-7 consecutive night shifts immediately prior to a laboratory-based, simulated night shift. For 7 days prior, participants worked their usual shift sequence, and sleep was assessed with logs and actigraphy. Participants completed a 10-minute auditory psychomotor vigilance task (PVT) at the start (~21:00 hours) and end (~07:00 hours) of the simulated night shift. Mean reaction times (RT), number of lapses and RT distribution was compared between those who worked 2-3 consecutive night shifts versus those who worked 4-7 shifts. Following 4-7 shifts, night shift workers had significantly longer mean RT at the start and end of shift, compared to those who worked 2-3 shifts. The slowest and fastest 10% RT were significantly slower at the start, but not end, of shift among participants who worked 4-7 nights. Those working 4-7 nights also demonstrated a broader RT distribution at the start and end of shift and had significantly slower RT based on cumulative distribution analysis (5 (th), 25 (th), 50 (th), 75 (th)percentiles at the start of shift 75th percentile at the end of shift). No group differences in sleep parameters were found for 7 days and 24 hours prior to the simulated night shift. A greater number of consecutive night shifts has a negative impact on neurobehavioral performance, likely due to cognitive slowing.
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.NLM.2015.11.009
Abstract: While intervening sleep promotes the consolidation of memory, it is well established that cognitive interference from competing stimuli can impede memory retention. The current study examined changes in motor skill learning across periods of wakefulness with and without competing stimuli, and periods of sleep with and without disruption from external stimuli. A napping study design was adopted where participants (N=44) either had (1) a 30min nap composed of Non-Rapid Eye Movement (NREM) sleep, (2) 30min NREM nap fragmented by audio tone induced arousals, (3) 45min of quiet wakefulness, or (4) 45min of active wakefulness. Measures of subjective sleepiness (KSS), alertness (PVT) and motor skill learning (Sequential Finger Tapping Task, SFTT) were completed in the morning and evening to assess performance pre- and post-nap or wakefulness. Following a practice session, change in motor skill performance was measured over a 10min post training rest interval, as well as following a 7h morning to evening interval comprising one of the four study conditions. A significant offline enhancement in motor task performance (13-23%) was observed following 10min of rest in all conditions. Following the long delay with the intervening nap/wake condition, there were no further offline gains or losses in performance in any sleep (uninterrupted/fragmented) or wake (quiet/active) condition. The current findings suggest that after controlling for offline gains in performance that occur after a brief rest and likely to due to the dissipation of fatigue, the subsequent effect of an intervening sleep or wake period on motor skill consolidation is not significant. Consistent with this null result, the impact of disrupting the sleep episode or manipulating activity during intervening wake also appears to be negligible.
Publisher: American Academy of Sleep Medicine (AASM)
Date: 15-09-2013
DOI: 10.5664/JCSM.2992
Publisher: Proceedings of the National Academy of Sciences
Date: 22-12-2015
Abstract: Drowsy driving is a major public health issue, particularly impacting the 9.5 million shift workers in America. Previous reports have assessed the impact of night work on driving in driving simulators. This real-vehicle driving study demonstrated increased objective and subjective drowsiness and degraded daytime driving performance in 16 night-shift workers while driving after a night of work, deteriorating with drive duration. No near-crashes occurred during driving after a night of sleep 11 occurred during driving after night-work all near-crashes occurred after at least 45 min of driving. Policy makers and night-workers should consider avoiding/minimizing driving or deploying effective countermeasures when driving after night-shift work to reduce drowsy driving and preventable crashes and injuries in this high-risk population.
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.BBR.2010.09.020
Abstract: Sleep deprivation has previously been shown to intensify neural and autonomic responses to increasingly negative stimuli. Here, we report how this potential bias to negative stimuli manifests itself in behavioural performance. One night of sleep loss led to increased impulsivity to negative stimuli, such that sleep deprived in iduals had an increased failure to inhibit a response and faster incorrect responses. This enhanced reactivity to negative stimuli has important consequences outside the confines of the laboratory.
Publisher: American Diabetes Association
Date: 16-02-2016
DOI: 10.2337/DB15-0999
Abstract: The risk of type 2 diabetes (T2D) is increased by abnormalities in sleep quantity and quality, circadian alignment, and melatonin regulation. A common genetic variant in a receptor for the circadian-regulated hormone melatonin (MTNR1B) is associated with increased fasting blood glucose and risk of T2D, but whether sleep or circadian disruption mediates this risk is unknown. We aimed to test if MTNR1B diabetes risk variant rs10830963 associates with measures of sleep or circadian physiology in intensive in-laboratory protocols (n = 58–96) or cross-sectional studies with sleep quantity and quality and timing measures from self-report (n = 4,307–10,332), actigraphy (n = 1,513), or polysomnography (n = 3,021). In the in-laboratory studies, we found a significant association with a substantially longer duration of elevated melatonin levels (41 min) and delayed circadian phase of dim-light melatonin offset (1.37 h), partially mediated through delayed offset of melatonin synthesis. Furthermore, increased T2D risk in MTNR1B risk allele carriers was more pronounced in early risers versus late risers as determined by 7 days of actigraphy. Our results provide the surprising insight that the MTNR1B risk allele influences dynamics of melatonin secretion, generating a novel hypothesis that the MTNR1B risk allele may extend the duration of endogenous melatonin production later into the morning and that early waking may magnify the diabetes risk conferred by the risk allele.
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.SMRV.2019.03.004
Abstract: Most objective drowsiness measures have limited ability to provide continuous, accurate assessment of drowsiness state in operational settings. Spontaneous eye blink parameters are ideal for drowsiness assessment as they are objective, non-invasive, and can be recorded continuously during regular activities. Studies that have assessed the spontaneous eye blink as a drowsiness measure are erse, varying greatly in respect to study design, eye blink acquisition technology and eye blink parameters assessed. The purpose of this narrative review is to collate these studies to determine 1) which eye blink parameters provide the best state drowsiness measures 2) how well eye blink parameters relate to and predict conventional drowsiness measures and 3) whether eye blink parameters can identify drowsiness impairment in obstructive sleep apnoea (OSA) - a highly prevalent disorder associated with excessive sleepiness and increased accident risk. In summary, almost all eye blink parameters varied consistently with drowsiness state, with blink duration and percentage of eye closure the most robust. All eye blink parameters were associated with and predicted conventional drowsiness measures, with generally fair to good accuracy. Eye blink parameters also showed utility for identifying OSA patients and treatment response, suggesting these parameters may identify drowsiness impairment in this group.
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.AAP.2019.105386
Abstract: Sleepiness is a major contributor to motor vehicle crashes and shift workers are particularly vulnerable. There is currently no validated objective field-based measure of sleep-related impairment prior to driving. Ocular parameters are promising markers of continuous driver alertness in laboratory and track studies, however their ability to determine fitness-to-drive in naturalistic driving is unknown. This study assessed the efficacy of a pre-drive ocular assessment for predicting sleep-related impairment in naturalistic driving, in rotating shift workers. Fifteen healthcare workers drove an instrumented vehicle for 2 weeks, while working a combination of day, evening and night shifts. The vehicle monitored lane departures and behavioural microsleeps (blinks >500 ms) during the drive. Immediately prior to driving, ocular parameters were assessed with a 4-min test. Lane departures and behavioural microsleeps occurred on 17.5 % and 10 % of drives that had pre-drive assessments, respectively. Pre-drive blink duration significantly predicted behavioural microsleeps and showed promise for predicting lane departures (AUC = 0.79 and 0.74). Pre-drive percentage of time with eyes closed had high accuracy for predicting lane departures and behavioural microsleeps (AUC = 0.73 and 0.96), although was not statistically significant. Pre-drive psychomotor vigilance task variables were not statistically significant predictors of lane departures. Self-reported sleep-related and hazardous driving events were significantly predicted by mean blink duration (AUC = 0.65 and 0.69). Measurement of ocular parameters pre-drive predict drowsy driving during naturalistic driving, demonstrating potential for fitness-to-drive assessment in operational environments.
Publisher: Oxford University Press (OUP)
Date: 02-2010
Publisher: Oxford University Press (OUP)
Date: 22-12-2017
DOI: 10.1093/SLEEP/ZSX195
Abstract: Extended duration (≥24 hours) work shifts (EDWSs) are associated with increased risk of motor vehicle crashes, and awareness of any impairment has important implications on legal accountability for any adverse driving outcome. The extent to which adverse driving events were preceded by predrive self-reported sleepiness was evaluated in medical residents after an EDWS. Sixteen resident physicians (10 females 29.2 ± 2.0 years) working EDWS were monitored when driving on their commute to and from the hospital (438 drives). Sleep and work hours were obtained from daily logs, and adverse driving outcomes were captured from a driving log completed at the end of each drive. Self-reported sleepiness (Karolinska Sleepiness Scale KSS) and objective drowsiness were captured using a time-st ed, hand-held device and infra-red reflectance oculography. Self-reported sleepiness and objective indices of drowsiness were positively correlated, and both were elevated following EDWSs. Compared with the commute to work, EDWSs were associated with more than double the self-reported adverse outcomes when driving home, significantly higher than drives to or from the day shift at comparable times of day. EDWSs more than tripled the odds of reporting sleep-related, inattentive, hazardous, or violation-driving events. The number and type of adverse event was predicted by the predrive KSS level and in a dose-dependent manner. Driving after an EDWS puts resident physicians/drivers and other road users at avoidable and unnecessary risk. Demonstrating self-reported sleepiness at the beginning of the drive is associated with adverse outcomes has serious implications on the legal accountability for driving when drowsy.
Publisher: Wiley
Date: 25-01-2022
DOI: 10.1111/JSR.13545
Abstract: Acoustic stimulation has been shown to enhance slow wave sleep and in turn, cognition, and now cardiac outcomes in young adults. With the emergence of commercial acoustic devices in the home, we sought to examine the impact of an acoustic, slow wave enhancing device on heart rate variability in healthy, middle‐aged males ( n = 24, 39.92 ± 4.15 years). Under highly controlled conditions, the participants were randomised to receive closed‐loop brain state‐dependent stimulation in the form of auditory tones (STIM), or no tones (SHAM), in a crossover design, separated by a 1 week washout period. STIM and SHAM were compared on measures of heart rate variability for the whole night and over the first three sleep cycles. We found an increase in slow wave activity following STIM compared with SHAM. There was a significant increase in high frequency power and standard deviation of the normalised RR‐intervals (SDNN) during the STIM condition compared with SHAM ( p 0.05), due to changes observed specifically during N3. In conclusion, heart rate variability appears to improve following acoustic slow wave sleep enhancement.
Publisher: Springer Science and Business Media LLC
Date: 08-2009
DOI: 10.3758/BRM.41.3.937
Publisher: Wiley
Date: 2008
DOI: 10.1002/HUP.931
Abstract: Caffeine is the most widely used stimulant to counteract sleepiness. However, little is known about any placebo effect of caffeine in sleepy people and the effect of suggestibility. Over a 95 min test period, and in a counterbalanced design, 16 young healthy adults underwent 3 x 30 min sessions at the psychomotor vigilance test (PVT), during an early afternoon 'dip' enhanced by a prior night's sleep restriction (5 h). On both occasions they were given a cup of a decaffeinated coffee once when the participant was verbally primed to suggest the coffee was caffeinated (Placebo) and on the other under neutral priming (Control). There were significantly fewer lapses and shorter reaction times following Placebo, for the initial two 30 min sessions, indicating that suggestion about consuming caffeine was effective in improving performance in moderately sleepy people.
Publisher: Informa UK Limited
Date: 23-11-2016
DOI: 10.1080/13803395.2015.1078295
Abstract: To simultaneously investigate the prevalence of and impact that the poststroke complications of daytime sleepiness, poor sleep quality, depression, and fatigue may be having upon deficits of sustained attention, as assessed using the Psychomotor Vigilance Task (PVT). Twenty-two patients with stroke (mean age: 68.23 ± 12.17 years) and 20 healthy control participants (mean age: 68.1 ± 9.5 years) completed subjective measures of daytime sleepiness, sleep quality, fatigue, and depression and an objective measure of sustained attention as assessed using the PVT. Patients with stroke compared to controls showed heightened levels of fatigue (p = .001, η(2) = .29) and depression (p = .002, η(2) = .23), plus greater deficits of sustained attention as reflected by poorer performance across all PVT outcome measures including: slower mean reaction times (p = .002, η(2) = .22) increased number of lapses (p = .002, η(2) = .24) and greater variability in reaction time (RT) responses (p = .016, η(2) = .15). Reaction time distribution analysis suggested that daytime sleepiness and sleep quality had little influence across PVT performance however, depressive symptomology was associated with longer RT responses, indicative of inattention, and fatigue impacted upon the entire distribution of PVT responses. PVT performance illustrated significant deficits across the domain of sustained attention for patients with stroke in comparison to healthy controls, in terms of inattention as well as slower sensory-motor speed. The common poststroke complications of depressive symptomology and fatigue appear to be associated with these deficits in sustained attention, warranting further investigation.
Publisher: Wiley
Date: 31-07-2018
DOI: 10.1111/JSR.12739
Abstract: Pupillary instability reflects alterations in autonomic nervous system activity and has been shown to reflect change in alertness. However, the extent to which it can predict subsequent performance impairment and alertness failure is not clear. Eighteen healthy young adults (group age = 21.44 ± 3.24 years, 10 men) underwent 40 hr of continuous wakefulness, completing an 11-min Pupillographic Sleepiness Test (PST), the Karolinska Sleepiness Scale and a 10-min Psychomotor Vigilance Task (PVT) every 2 hr. Waking electroencephalography was recorded continuously and scored for microsleeps and slow eye movements (SEMs) during PVTs. Pupillary instability was sensitive to time awake, significantly increasing after 18 hr of wakefulness. The time course of impairment was almost identical to PVT lapses, microsleeps and SEMs. Receiver operating characteristic curve analysis demonstrated reasonable sensitivity and specificity of pupillary instability in correctly classifying PVT lapses, microsleeps and SEMs above in idual baseline thresholds (all AUC values >0.78, p < 0.0001). Preliminary cut-off scores ranging from 10 to 11.5 mm/min for varying impairment thresholds are proposed for young adults. If reproducible in field settings, the PST may be a strong candidate as a fitness for duty/fitness to drive tool for detecting drowsiness-related impairment.
Publisher: Wiley
Date: 03-08-2012
DOI: 10.1111/J.1365-2869.2012.01038.X
Abstract: To assess the relationships between sleepiness and the incidence of adverse driving events in nurses commuting to and from night and rotating shifts, 27 rotating and permanent night shift-working nurses were asked to complete daily sleep and duty logs, and wear wrist-activity monitors for 2 weeks (369 driving sessions). During all commutes, ocular measures of drowsiness, including the Johns Drowsiness Scale score, were assessed using the Optalert™ system. Participants self-reported their subjective sleepiness at the beginning and end of each drive, and any events that occurred during the drive. Rotating shift nurses reported higher levels of sleepiness compared with permanent night shift nurses. In both shift-working groups, self-reported sleepiness, drowsiness and drive events were significantly higher during commutes following night shifts compared with commutes before night shifts. Strong associations were found between objective drowsiness and increased odds of driving events during commutes following night shifts. Maximum total blink duration (mean = 7.96 s) during the drive and pre-drive Karolinska Sleepiness Scale (mean = 5.0) were associated with greater incidence of sleep-related events [OR, 5.35 (95% CI, 1.32, 21.60), OR, 1.69 (95% CI, 1.04, 2.73), respectively]. Inattention was strongly associated with a Johns Drowsiness Scale score equal to or above 4.5 [OR, 4.58 (95% CI, 1.26-16.69)]. Hazardous driving events were more likely to occur when drivers had been awake for 16 h or more [OR, 4.50 (95% CI, 1.81, 11.16)]. Under real-world driving conditions, shift-working nurses experience high levels of drowsiness as indicated by ocular measures, which are associated with impaired driving performance following night shift work.
Publisher: Proceedings of the National Academy of Sciences
Date: 28-05-2019
Abstract: Electric lighting has fundamentally altered how the human circadian clock synchronizes to the day/night cycle. Exposure to light after dusk is pervasive in the modern world. We examined group-level sensitivity of the circadian system to evening light and the degree to which sensitivity varies between in iduals. We found that, on average, humans are highly sensitive to evening light. Specifically, 50% suppression of melatonin occurred at lux, which is comparable to or lower than typical indoor lighting used at night, as well as light produced by electronic devices. Significantly, there was a -fold difference in sensitivity to evening light across in iduals. Interin idual differences in light sensitivity may explain differential vulnerability to circadian disruption and subsequent impact on human health.
Publisher: SAGE Publications
Date: 02-2017
Abstract: The measurement of circulating levels of brain-derived neurotrophic factor (BDNF) has been proposed to be a marker of disease and an indicator of recovery. Thus, knowing the temporal pattern and influence of potential circadian rhythms is important. Although several studies have measured BDNF at different times of day, no studies have done so while controlling for potential masking influences such as sleep and activity. Further, no previous study has examined circadian rhythms within in iduals. We examined circadian rhythms in plasma BDNF while minimizing masking from behavioral and environmental factors using a 30-h constant routine (CR) protocol. In a s le of 39 healthy adults, we found significant circadian rhythms in 75% of women and 52% of men. The timing of the acrophase of the BDNF rhythm, however, was unrelated to clock time in women, while it was related to clock time in men. These results indicate that the use of single-s le measures of plasma BDNF as a marker of disease will be unreliable, especially in women. Repeated plasma BDNF s les over a 24-h period within in iduals would be needed to reveal abnormalities related to disease states.
Publisher: Oxford University Press (OUP)
Date: 19-08-2022
Publisher: Public Library of Science (PLoS)
Date: 23-04-2019
Publisher: Informa UK Limited
Date: 02-2013
DOI: 10.1080/13803395.2012.762340
Abstract: Deficits in sustained attention are common following traumatic brain injury (TBI), as a result of primary (i.e., neuropathology) and/or secondary factors (i.e., fatigue, sleep disturbance, depressed mood). The extent to which secondary factors play a role in attention deficits is relatively unexamined. Moreover, the Psychomotor Vigilance Task (PVT) is seldom used in TBI assessment despite its sensitivity to secondary factors observed following injury. The primary aim of the current study was to examine the usefulness of the auditory PVT in identifying attentional difficulties in patients with TBI compared with noninjured controls, and also to explore the impact of fatigue, sleep quality, and daytime sleepiness on sustained attention performances. Participants (n = 20 per group) completed the auditory PVT and self-report measures of fatigue, sleep quality, daytime sleepiness, and depression. Compared to controls, patients with TBI had widespread PVT deficits including slower response times, increased response variability and attention lapses, and delayed responding in the slowest 10% of responses. Distribution analyses suggested this was likely due to generalized cognitive slowing. Self-reported secondary factors had varying impacts on aspects of PVT performance, with self-reported fatigue exhibiting a more global impact on attention performance. The auditory PVT is a sensitive measure of sustained attention deficits in patients with TBI, with aspects of performance influenced by fatigue, sleep disturbance, and depression.
Publisher: Wiley
Date: 19-02-2010
DOI: 10.1111/J.1365-2869.2009.00767.X
Abstract: Although it is well known that sleep loss results in poor judgement and decisions, little is known about the influence of social context in these processes. Sixteen healthy young adults underwent three games involving bargaining (‘Ultimatum’ and ‘Dictator’) and trust, following total sleep deprivation (TSD) and during rested wakefulness (RW), in a repeated‐measures, counterbalanced design. To control for repeatability, a second group ( n = 16) was tested twice under RW conditions. Paired anonymously with another in idual, participants made their simple social interaction decisions facing real monetary incentives. For bargaining, following TSD participants were more likely to reject unequal‐split offers made by their partner, despite the rejection resulting in a zero monetary payoff for both participants. For the trust game, participants were less likely to place full trust in their anonymous partner. Overall, we provide novel evidence that following TSD, the conflict between personal financial gain and payoff equality is focused upon avoidance of unfavourable inequality (i.e. unfairness). This results in the rejection of unfair offers at personal monetary cost, and the lack of full trust which would expose one to being exploited in the interaction. As such, we suggest that within a social domain decisions may be more influenced by emotion following TSD, which has fundamental consequences for real‐world decision‐making involving social exchange.
Publisher: Wiley
Date: 09-2019
DOI: 10.1111/IMJ.14423
Abstract: The Australian National Road Safety Strategy 2011-2020 framed a 19-point action plan targeting a 30% reduction in road deaths by 2020. In achieving a 9% reduction to date, it is likely to fail this target. Sleep disorders and sleep loss did not feature prominently in this strategy, despite their high prevalence and effect on drowsiness and crashes. This article gathers sleep experts to provide recommendations addressing driver education and legislation to assist the response to this public health problem. Developments in drowsiness detection and sleep disorders management are also presented that offer innovative countermeasures that could enhance road safety beyond 2020.
Publisher: Elsevier BV
Date: 12-2021
DOI: 10.1016/J.SMRV.2021.101533
Abstract: Driver drowsiness contributes to 10-20% of motor vehicle crashes. To reduce crash risk, ideally drivers would be aware of the drowsy state and cease driving. The extent to which drivers can accurately identify sleepiness remains under much debate. We systematically examined whether in iduals are aware of sleepiness while driving, and whether this accurately reflects driving impairment, using meta-analyses and narrative review. Within this scope, there is high variability in measures of subjective sleepiness, driving performance and physiologically-derived drowsiness, and statistical analyses. Thirty-four simulated/naturalistic driving studies were reviewed. To summarise, drivers were aware of sleepiness, and this was associated to physiological drowsiness and driving impairment, such that high levels of sleepiness significantly predicted crash events and lane deviations. Subjective sleepiness was more strongly correlated (i) with physiological drowsiness compared to driving outcomes (ii) under simulated driving conditions compared to naturalistic drives and (iii) when examined using the Karolinska sleepiness scale (KSS) compared to other measures. Gaps remain in relation to how age, sex, and varying degrees of sleep loss may influence this association. This review provides evidence that drivers are aware of drowsiness while driving, and stopping driving when feeling 'sleepy' may significantly reduce crash risk.
Publisher: Oxford University Press (OUP)
Date: 06-06-2022
Abstract: Sleep loss has been shown to alter risk preference during decision-making. However, research in this area has largely focussed on the effects of total sleep deprivation (TSD), while evidence on the effects of sleep restriction (SR) or the potentially moderating role of sex on risk preference remains scarce and unclear. The present study investigated risky decision-making in 47 healthy young adults who were assigned to either of two counterbalanced protocols: well-rested (WR) and TSD, or WR and SR. Participants were assessed on the Lottery Choice Task (LCT), which requires a series of choices between two risky gambles with varying risk levels. Analyses on the pooled dataset indicated across all sleep conditions, participants were generally more risk-seeking when trying to minimise financial loss (LOSSES) than while trying to maximise financial gain (GAINS). On GAINS trials, female participants were more risk-averse during TSD and SR, whereas male participants remained unchanged. On LOSSES trials, female participants remained unchanged during TSD and SR, whereas male participants became more risk-seeking during TSD. Our findings suggest the relationship between sleep loss and risk preference is moderated by sex, whereby changes in risk preference after TSD or SR differ in men and women depending on whether the decision is framed in terms of gains or losses.
Publisher: Elsevier BV
Date: 06-2004
Publisher: Wiley
Date: 22-01-2010
DOI: 10.1002/SMI.1301
Publisher: Oxford University Press (OUP)
Date: 09-05-2023
Abstract: To examine whether drivers are aware of sleepiness and associated symptoms, and how subjective reports predict driving impairment and physiological drowsiness. Sixteen shift workers (19–65 years 9 women) drove an instrumented vehicle for 2 hours on a closed-loop track after a night of sleep and a night of work. Subjective sleepiness/symptoms were rated every 15 minutes. Severe and moderate driving impairment was defined by emergency brake maneuvers and lane deviations, respectively. Physiological drowsiness was defined by eye closures (Johns drowsiness scores) and EEG-based microsleep events. All subjective ratings increased post night-shift (p & 0.001). No severe drive events occurred without noticeable symptoms beforehand. All subjective sleepiness ratings, and specific symptoms, predicted a severe (emergency brake) driving event occurring in the next 15 minutes (OR: 1.76–2.4, AUC & 0.81, p & 0.009), except “head dropping down”. Karolinska Sleepiness Scale (KSS), ocular symptoms, difficulty keeping to center of the road, and nodding off to sleep, were associated with a lane deviation in the next 15 minutes (OR: 1.17–1.24, p& .029), although accuracy was only “fair” (AUC 0.59–0.65). All sleepiness ratings predicted severe ocular-based drowsiness (OR: 1.30–2.81, p & 0.001), with very good-to-excellent accuracy (AUC & 0.8), while moderate ocular-based drowsiness was predicted with fair-to-good accuracy (AUC & 0.62). KSS, likelihood of falling asleep, ocular symptoms, and “nodding off” predicted microsleep events, with fair-to-good accuracy (AUC 0.65–0.73). Drivers are aware of sleepiness, and many self-reported sleepiness symptoms predicted subsequent driving impairment hysiological drowsiness. Drivers should self-assess a wide range of sleepiness symptoms and stop driving when these occur to reduce the escalating risk of road crashes due to drowsiness.
Publisher: Wiley
Date: 29-04-2003
Abstract: Low frequency (< 1 Hz) delta EEG in sleep is of increasing interest as it indicates cortical reorganization, especially in the prefrontal cortex (PFC). Other research shows that delta power in sleep is positively linked to waking cerebral metabolic rate. Such findings suggest that < 1 Hz activity may reflect waking performance at neuropsychological tests specific to the PFC. We investigated this unexplored area. Sleep EEGs (Fp1-F3, Fp2-F4, O1-P3, O2-P4) were recorded in 24 healthy 61-75-year-olds. We found significant associations between 0.5-1.0 Hz power from the left frontal EEG channel, in the first non-REM period, and performance at tasks more specific to the left PFC (e.g., nonverbal planning and verbal fluency). This association was absent from the posterior channels. Neither age nor response times were confounding factors. This potential sleep EEG marker for PFC neuropsychological function in healthy, older people also points to further uses of the sleep EEG in understanding the role of sleep.
Publisher: Wiley
Date: 04-10-2022
DOI: 10.1111/JSR.13730
Abstract: This study aimed to examine the impact of break duration between consecutive shifts, time of break onset, and prior shift duration on total sleep time (TST) between shifts in heavy vehicle drivers (HVDs), and to assess the interaction between break duration and time of break onset. The sleep (actigraphy and sleep diaries) and work shifts (work diaries) of 27 HVDs were monitored during their usual work schedule for up to 9 weeks. Differences in TST between consecutive shifts and days off were assessed. Linear mixed models (followed by pairwise comparisons) assessed whether break duration, prior shift duration, time of break onset, and the interaction between break duration and break onset were related to TST between shifts. Investigators found TST between consecutive shifts (mean [SD] 6.38 [1.38] h) was significantly less than on days off (mean [SD] 7.63 [1.93] h p < 0.001). Breaks starting between 12:01 and 8:00 a.m. led to shorter sleep (p < 0.05) compared to breaks starting between 4:01 and 8:00 p.m. Break durations up to 7, 9, and 11 h (Australian and European minimum break durations) resulted in a mean (SD) of 4.76 (1.06), 5.66 (0.77), and 6.41 (1.06) h of sleep, respectively. The impact of shift duration prior to the break and the interaction between break duration and time of break were not significant. HVDs' sleep between workdays is influenced independently by break duration and time of break onset. This naturalistic study provides evidence that current break regulations prevent sufficient sleep duration in this industry. Work regulations should evaluate appropriate break durations and break onset times to allow longer sleep opportunities for HVDs.
Publisher: Wiley
Date: 14-06-2023
DOI: 10.1111/JSR.13933
Abstract: Understanding whether drivers can accurately assess sleepiness is essential for educational c aigns advising drivers to stop driving when feeling sleepy. However, few studies have examined this in real‐world driving environments, particularly among older drivers who comprise a large proportion of all road users. To examine the accuracy of subjective sleepiness ratings in predicting subsequent driving impairment and physiological drowsiness, 16 younger (21–33 years) and 17 older (50–65 years) adults drove an instrumented vehicle for 2 h on closed loop under two conditions: well‐rested and 29 h sleep deprivation. Sleepiness ratings (Karolinska Sleepiness Scale, Likelihood of Falling Asleep scale, Sleepiness Symptoms Questionnaire) were obtained every 15min, alongside lane deviations, near crash events, and ocular indices of drowsiness. All subjective sleepiness measures increased with sleep deprivation for both age groups ( p 0.013). While most subjective sleepiness ratings significantly predicted driving impairment and drowsiness in younger adults (OR: 1.7–15.6, p 0.02), this was only apparent for KSS, likelihood of falling asleep, and “difficulty staying in the lane for the older adults” (OR: 2.76–2.86, p = 0.02). This may be due to an altered perception of sleepiness in older adults, or due to lowered objective signs of impairment in the older group. Our data suggest that (i) younger and older drivers are aware of sleepiness (ii) the best subjective scale may differ across age groups and (iii) future research should expand on the best subjective measures to inform of crash risk in older adults to inform tailored educational road safety c aigns on signs of sleepiness.
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.NLM.2019.107086
Abstract: Age-related reductions in slow wave activity (SWA) and increased fragmentation during sleep play a key role in memory impairment. As the prefrontal cortex is necessary for the control processes relevant to memory encoding, including utilisation of internal heuristics such as semantic clustering, and is preferentially vulnerable to sleep disturbance, our study examined how SWA and sleep fragmentation relates to memory performance in in iduals with Subjective Cognitive Decline (SCD). Thirty older adults with SCD (Mean Age = 69.34, SD = 5.34) completed a neurocognitive test battery, including the California Verbal Learning Test, which was used to assess semantic clustering. One week later, participants were admitted to the laboratory for a two night visit. SWA and sleep fragmentation were captured using sleep polysomnography. Next-day memory performance was tested using the Rey Auditory Verbal Learning Test. Poorer sleep (reduced SWA increased arousals) was associated with reduced semantic clustering, which mediated impairment on verbal memory and learning tests conducted both the day after sleep was recorded (for both SWA and arousals), and a week prior (for arousals only). We demonstrate semantic clustering mediated the well described associations between sleep and verbal memory. As these strategies are a component of cognitive training interventions, future research may examine the role of simultaneous sleep interventions for improving cognitive training outcomes.
Publisher: Elsevier BV
Date: 02-2018
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.SLEEP.2012.11.014
Abstract: Laboratory-based studies show that drowsiness increases the propensity to become distracted. As this phenomenon has not been investigated in drowsy drivers, we underwent a pilot study under realistic monotonous driving conditions to see if distraction was more apparent when drowsy if so, how does it affect driving performance? A repeated measures counterbalanced design whereby participants drove for two hours in a fully interactive car simulator during the bi circadian afternoon drive, after a night of either normal (baseline) or restricted sleep to five hours (sleep restriction). Videos of drivers' faces were analysed blind for short ( 3 s) distractions, in which drivers took their eyes off the road ahead. These results were compared with the likelihood of simultaneous lane-drifting incidents, when at least two wheels left the driving lane. More distractions occurred after restricted sleep (p<0.005) for both short and long distractions (p<0.05). There was an overall significant (p<0.02) positive correlation between distractions and driving incidents for both conditions but with significantly more distraction-related incidents after sleep restriction (p<0.03). Following restricted sleep, drivers had an increased propensity to become distracted, which was associated with an increased likelihood of poor driving performance as evidenced by the car leaving the driving lane.
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.AAP.2017.11.004
Abstract: The morning commute home is an especially vulnerable time for workers engaged in night shift work due to the heightened risk of experiencing drowsy driving. One strategy to manage this risk is to monitor the driver's state in real time using an in vehicle monitoring system and to alert drivers when they are becoming sleepy. The primary objective of this study is to build and evaluate predictive models for drowsiness events occurring in morning drives using a variety of physiological and performance data gathered under a real driving scenario. We used data collected from 16 night shift workers who drove an instrumented vehicle for approximately two hours on a test track on two occasions: after a night shift and after a night of rest. Drowsiness was defined by two outcome events: performance degradation (Lane-Crossing models) and electroencephalogram (EEG) characterized sleep episodes (Microsleep Models). For each outcome, we assessed the accuracy of sets of predictors, including or not including a driver factor, eyelid measures, and driving performance measures. We also compared the predictions using different time intervals relative to the events (e.g., 1-min prior to the event through 10-min prior). By examining the Area Under the receiver operating characteristic Curve (AUC), accuracy, sensitivity, and specificity of the predictive models, the results showed that the inclusion of an in idual driver factor improved AUC and prediction accuracy for both outcomes. Eyelid measures improved the prediction for the Lane-Crossing models, but not for Microsleep models. Prediction performance was not changed by adding driving performance predictors or by increasing the time to the event for either outcome. The best models for both measures of drowsiness were those considering driver in idual differences and eyelid measures, suggesting that these indicators should be strongly considered when predicting drowsiness events. The results of this paper can benefit the development of real-time drowsiness detection and help to manage drowsiness to avoid related motor-vehicle crashes and loss.
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 03-2023
End Date: 03-2026
Amount: $430,986.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2016
End Date: 12-2019
Amount: $207,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2023
End Date: 05-2028
Amount: $4,583,816.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2013
End Date: 06-2016
Amount: $120,349.00
Funder: Australian Research Council
View Funded Activity