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Objectives Fibromyalgia is characterized by chronic widespread pain, mood, and sleep disturbance. Pharmacological treatments have modest efficacy and are associated with negative side effects, and alternative approaches are needed. Morning bright light treatment may assist in the management of fibromyalgia as it can reduce depressive symptoms, improve sleep, and advance circadian timing. Methods Sixty people with fibromyalgia (58 women, mean age 41.8 ± 13.3 years) were enrolled in a study comparing 4 weeks of a 1-hour daily morning bright light treatment (active treatment) to a morning dim light treatment (comparison treatment). Both light treatments included behavioral procedures to stabilize sleep timing. The morning bright light treatment was expected to produce larger improvements in pain and function than the dim light treatment and larger improvements in potential mediators (mood, sleep, and circadian timing). Results Both the bright and dim light treatment groups achieved significant but similar levels of improvement in pain intensity, pain interference, physical function, depressive symptoms, and sleep disturbance. Overall, the sample on average displayed a clinically meaningful improvement in the Fibromyalgia Impact Questionnaire-Revised score (mean reduction of 11.2 points), comparable to that reported following physical exercise treatments. Minimal side effects were observed. Conclusions Findings indicate that the effects of a morning bright light treatment did not exceed those of a comparison dim light treatment; yet the changes on average in both conditions revealed clinically meaningful improvements. Future research is warranted to identify what elements of this trial may have contributed to the observed effects. [ABSTRACT FROM AUTHOR]

Circadian clocks control the timing of many physiological events in the 24-h day. When individuals undergo an abrupt external shift (e.g., change in work schedule or travel across multiple time zones), circadian clocks become misaligned with the new time and may take several days to adjust. Chronic circadian misalignment, e.g., as a result of shift work, has been shown to lead to several physical and mental health problems. Despite the serious health implications of circadian misalignment, relatively little is known about how genetic variation affects an individual's ability to entrain to abrupt external changes. Accordingly, we used the one-hour advance from the onset of daylight saving time (DST) as a natural experiment to comprehensively study how individual heterogeneity affects the shift of sleep/wake cycles in response to an abrupt external time change. We found that individuals genetically predisposed to a morning tendency adjusted to the advance in a few days, while genetically predisposed evening-inclined individuals had not shifted. Observing differential effects by genetic disposition after a one-hour advance underscores the importance of heterogeneity in adaptation to external schedule shifts. These genetic differences may affect how individuals adjust to jet lag or shift work as well. [ABSTRACT FROM AUTHOR]

Female shift workers are at increased risk for negative reproductive outcomes, and animal evidence suggests that manipulation of the light-dark cycle is detrimental to early gestation in female mice. Specifically, failure of implantation may be responsible for these findings. The objective of this study was to better delineate which reproductive processes are vulnerable to detrimental effects of maternal circadian disturbance. We exposed mice undergoing embryo transfer to repetitive phase advances of the photoperiod. Embryos were derived from donor sperm and eggs from mice living in normal light-dark conditions to isolate the effects of photoperiod disruption on uterine receptivity and early gestation. Twenty-eight mice receiving embryo transfer underwent an experimental light-dark condition (advance of lights on and lights off by 6 hours every 4 days). Twenty-eight mice remained in a normal light-dark condition. Animals lived in their assigned light-dark condition beginning 2 weeks prior to embryo transfer and ending the day of uterine necropsy (post-coitus day 14.5). Wilcoxon-Mann-Whitney test demonstrated no significant differences between control and experimental light-dark conditions in pups (Z=0.10, p=.92), resorptions (Z=0.20, p=.84), or implantations (Z=-0.34, p=.73). Pup and placental weights were similar between groups. In this investigation, uterine receptivity and maintenance of early gestation were preserved despite recurrent phase advances in photoperiod. This finding, in the context of the current literature, suggests that the negative effects of circadian disruption are mediated by reproductive processes upstream of implantation. [ABSTRACT FROM AUTHOR]