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Based on human and animal research, it appears that light administered in the last two hours of sleep might be particularly effective as an antidepressant and in advancing circadian rhythms. Green light might be more effective than white light. An obvious advantage of light treatment during sleep is that disturbance and time cost during waking hours might be avoided. For these reasons, we decided to explore effects of a light treatment with a green light mask used for in the last hours of sleep. Subjects were 30 adults aged 18-35 years. This protocol took take place at the subjects' homes and lasted 15 days after recruitment (3-day baseline period and 12-day intervention period). Throughout the study, participants maintained sleep and compliance diaries and wore a wrist actigraph. The study was a randomized, controlled clinical trial of a bright green light mask versus a dim red light mask. The two treatments were a bright green light and dim red light. Post-treatment interviews showed that all subjects reported some discomfort from the masks, but compliance was good overall. Symptom inventory scores did not differentiate groups, suggesting no significant differences in side effects. Mood ratings and sleep questionnaires did not differentiate groups. Sleep diaries distinguished groups, suggesting worse sleep overall in the green mask group. Actigraphy showed a significant circadian phase advance in the green light group. This suggests that the green light had a physiological effect. These findings suggest that green light masks are safe and tolerable; while the green light mask worsened perceived sleep overall, no specific factors were implicated and such complaints may simply be due to earlier awakening caused by a phase advance. Also, early morning green light presented during sleep produced a significant phase shift, suggesting that while there were no symptom benefits evidenced in this healthy sample, green light masks may be useful in clinical and research applications (e.g., mood disorders, endocrine functioning, delayed sleep phase syndrome) where circadian phase shifts have resulted in positive outcomes

Sleep disordered breathing (SDB) is highly prevalent among patients with cardiovascular disease (CVD), and the relationship between SDB and CVD may be bidirectional. However, SDB remains underdiagnosed and undertreated. One of the major barriers identified by cardiologists is lack of satisfaction with SDB therapy. This situation could be the result of the discordance between treatment and the pathophysiological characteristics of SDB. This condition is caused by multiple pathophysiological mechanisms, which could be classified into upper airway anatomic compromise, pharyngeal dilator muscle dysfunction, and ventilatory control instability. However, the effective treatment of SDB remains limited, and positive airway pressure therapy is still the mainstay of the treatment. Therefore, we review the pathophysiological characteristics of SDB in this article, and we propose to provide individualized treatment of SDB based on the underlying mechanism. This approach requires further study but could potentially improve adherence and success of therapy.

Bright light in the blue-green range, administered in the early morning hours (prior to waking) may be particularly effective in shifting circadian rhythms and may increase gonadotropin production. Accordingly, we tested the feasibility and utility of a mask that emits bright blue/green light (compared to a similar mask that emitted a dim red light) towards the end of sleep in a randomized, placebo-controlled pilot study. The study included a 3-day baseline period, immediately followed by a 12-day intervention period. Subjects were 30 healthy young men with minimal-mild depression. The bright light masks were well-tolerated and demonstrated adequate safety and feasibility. Following the intervention, those who wore the bright light mask demonstrated altered sleep timing suggestive of an earlier sleep period, and excreted a slight increase in follicle-stimulating hormone. Overall, light masks may prove useful in future studies of bright light therapy.

Objective

Sleep duration is associated with obesity and cardiometabolic disease. It is unclear, though, how these relationship differs across age groups.

Methods

Data from 2007 to 2008 National Health and Nutrition Examination Survey (NHANES) were used, including respondents aged 16+ with complete data (N = 5,607). Sleep duration and age were evaluated by self-report, and body mass index (BMI) was assessed objectively. Sleep duration was evaluated continuously and categorically [very short (≤4 h), short (5-6 h), and long (≥9 h) versus average (7-8 h)]. Age was also evaluated continuously and categorically [adolescent (16-17 years), young adult (18-29 years), early middle age (30-49 years), late middle age (50-64 years), and older adult (≥65 years)].

Results

There was a significant interaction with age for both continuous (Pinteraction  = 0.014) and categorical (Pinteraction  = 0.035) sleep duration. A pseudo-linear relationship was seen among the youngest respondents, with the highest BMI associated with the shortest sleepers and the lowest BMI associated with the longest sleepers. This relationship became U-shaped in middle-age, and less of a relationship was seen among the oldest respondents.

Conclusions

These findings may provide insights for clinical recommendations and could help to guide mechanistic research regarding the sleep-obesity relationship.

Physiological and cellular functions operate in a 24-hour cyclical pattern orchestrated by an endogenous process known as the circadian rhythm. Circadian rhythms represent intrinsic oscillations of biological functions that allow for adaptation to cyclic environmental changes. Key clock genes that affect the persistence and periodicity of circadian rhythms include BMAL1/CLOCK, Period 1, Period 2, and Cryptochrome. Remarkable progress has been made in our understanding of circadian rhythms and their role in common medical conditions. A critical review of the literature supports the association between circadian misalignment and adverse health consequences in sepsis, obstructive lung disease, obstructive sleep apnea, and malignancy. Circadian misalignment plays an important role in these disease processes and can affect disease severity, treatment response, and survivorship. Normal inflammatory response to acute infections, airway resistance, upper airway collapsibility, and mitosis regulation follows a robust circadian pattern. Disruption of normal circadian rhythm at the molecular level affects severity of inflammation in sepsis, contributes to inflammatory responses in obstructive lung diseases, affects apnea length in obstructive sleep apnea, and increases risk for cancer. Chronotherapy is an underused practice of delivering therapy at optimal times to maximize efficacy and minimize toxicity. This approach has been shown to be advantageous in asthma and cancer management. In asthma, appropriate timing of medication administration improves treatment effectiveness. Properly timed chemotherapy may reduce treatment toxicities and maximize efficacy. Future research should focus on circadian rhythm disorders, role of circadian rhythm in other diseases, and modalities to restore and prevent circadian disruption.

Circadian alignment of rest-activity rhythms is an essential biological process that may be vulnerable to misalignment in critically ill patients. We evaluated circadian rest-activity rhythms in critically ill patients and their association with baseline (e.g. age) and clinical (e.g. mechanical ventilation status) variables, along with intensive care unit light-dark cycles. Using wrist actigraphy, we collected 48-hr activity and light exposure data from critically ill patients in a tertiary care medical intensive care unit. We evaluated circadian rest-activity rhythms using COSINOR and non-parametric circadian rhythm analysis models, and stratified these data across baseline and clinical variables. We used linear regression to evaluate the association of circadian rest-activity and light-dark exposure rhythms. In COSINOR and non-parametric circadian rhythm analysis analyses, the 34 medical intensive care unit patients completing 48-hr actigraphy recordings exhibited mean MESOR (mean activity levels of a fitted curve) and amplitudes of 0.50 ± 0.32 and 0.20 ± 0.19 movements per 30-s epoch, with high interdaily variability. Patients who were older, mechanically ventilated, sedated, restrained and with higher organ failure scores tended to exhibit greater circadian rest-activity misalignment, with three of 34 (9%) patients exhibiting no circadian rhythmicity. Circadian light-dark exposure misalignment was observed as well and was associated with rest-activity misalignment (p = 0.03). Critically ill patients in our MICU experienced profound circadian rest-activity misalignment, with mostly weak or absent rhythms, along with circadian light-dark exposure misalignment. Potentially modifiable factors contributing to rest-activity misalignment (i.e. mechanical ventilation, restraints, low daytime light levels) highlight possible targets for future improvement efforts.