ORCID Profile
0000-0002-3943-416X
Current Organisation
Pennsylvania State University
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Publisher: Proceedings of the National Academy of Sciences
Date: 02-05-2011
Abstract: The circadian rhythms of melatonin and body temperature are set to an earlier hour in women than in men, even when the women and men maintain nearly identical and consistent bedtimes and wake times. Moreover, women tend to wake up earlier than men and exhibit a greater preference for morning activities than men. Although the neurobiological mechanism underlying this sex difference in circadian alignment is unknown, multiple studies in nonhuman animals have demonstrated a sex difference in circadian period that could account for such a difference in circadian alignment between women and men. Whether a sex difference in intrinsic circadian period in humans underlies the difference in circadian alignment between men and women is unknown. We analyzed precise estimates of intrinsic circadian period collected from 157 in iduals (52 women, 105 men aged 18–74 y) studied in a month-long inpatient protocol designed to minimize confounding influences on circadian period estimation. Overall, the average intrinsic period of the melatonin and temperature rhythms in this population was very close to 24 h [24.15 ± 0.2 h (24 h 9 min ± 12 min)]. We further found that the intrinsic circadian period was significantly shorter in women [24.09 ± 0.2 h (24 h 5 min ± 12 min)] than in men [24.19 ± 0.2 h (24 h 11 min ± 12 min) P 0.01] and that a significantly greater proportion of women have intrinsic circadian periods shorter than 24.0 h (35% vs. 14% P 0.01). The shorter average intrinsic circadian period observed in women may have implications for understanding sex differences in habitual sleep duration and insomnia prevalence.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Wiley
Date: 09-2012
DOI: 10.1002/ANA.23636
Publisher: Elsevier BV
Date: 02-2018
Publisher: American Academy of Sleep Medicine (AASM)
Date: 15-09-2013
DOI: 10.5664/JCSM.2992
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: 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: Elsevier BV
Date: 06-2011
Publisher: Informa UK Limited
Date: 18-04-2016
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.
No related grants have been discovered for Anne-Marie Chang.