Clocks & Sleep, Volume 1, Issue 4 (December 2019) – 8 articles

We examined whether ambient lighting conditions during extended wakefulness modulate the homeostatic response to sleep loss as indexed by. slow wave sleep (SWS) and electroencephalographic (EEG) slow-wave activity (SWA) in healthy young and older volunteers. Thirty-eight young and older participants underwent 40 hours of extended wakefulness [i.e., sleep deprivation (SD)] once under dim light (DL: 8 lux, 2800 K), and once under either white light (WL: 250 lux, 2800 K) or blue-enriched white light (BL: 250 lux, 9000 K) exposure. Subjective sleepiness was assessed hourly and polysomnography was quantified during the baseline night prior to the 40-h SD and during the subsequent recovery night. Both the young and older participants responded with a higher homeostatic sleep response to 40-h SD after WL and BL than after DL. This was indexed by a significantly faster intra-night accumulation of SWS and a significantly higher response in relative EEG SWA during the recovery night after WL and BL than after DL for both age groups. No significant differences were observed between the WL and BL condition for these two particular SWS and SWA measures. Subjective sleepiness ratings during the 40-h SD were significantly reduced under both WL and BL compared to DL, but were not significantly associated with markers of sleep homeostasis in both age groups. Our data indicate that not only the duration of prior wakefulness, but also the experienced illuminance during wakefulness affects homeostatic sleep regulation in humans. Thus, working extended hours under low illuminance may negatively impact subsequent sleep intensity in humans. Full article

Poor sleep quality is extremely prevalent, with about one third of adults in the USA obtaining less than the recommended amount of sleep. In addition, poor sleep quality has been linked to an increased risk of many conditions, including diabetes, hypertension, psychiatric conditions, and overall all-cause mortality. Research has shown that sleep disturbance does impact skin disease, although many details of this relationship are still unclear. The goal of this study is to determine if there is a relationship between acne severity and sleep quality in adults. Forty subjects with acne were recruited from dermatology clinics in Cleveland, OH, to participate in this study. Acne severity was assessed using the Global Acne Grading Scale (GAGS). To assess sleep quality, subjects completed the Pittsburgh Sleep Quality Index (PSQI) and completed a seven-day sleep journal. Subjects also completed the Dermatology Life Quality Index (DLQI), the Patient Health Questionnaire-2 (PHQ-2), and provided information about current and past acne treatments as well as their opinion regarding their own acne severity and exacerbating factors. Our findings support the hypothesis that there is a potential relationship between sleep quality and acne. Full article

Sleepiness decreases alertness and results in decrements in performance. This is especially problematic in the healthcare field due to restricted sleep from shift-work. Sleepiness increases medical errors, but it also affects emotions and interpersonal interactions. Empathy in physicians is a desirable trait which is associated with increased patient recovery rates and patient satisfaction, and decreased use of pain medication. Shift-work may alter empathy in physicians and affect patient outcomes, but the effects of sleepiness on empathy are unknown. Empathy, which is related to burnout, declines during medical school, while incidence of burnout increases. This study assessed the effect of sleepiness from time of day (TOD) and 12 h shifts on empathy and burnout in medical students. Participants were tested on sleepiness and empathy prior to and immediately following a 12 h Emergency Medical Technician shift. Burnout was assessed following each shift to determine if it was affected by sleepiness, empathy, and shift. TOD affected empathy, with empathy highest in the evening. Sleepiness from working 12 h shifts resulted in decreased empathy and increased burnout, with females showing higher rates on the exhaustion component of burnout. This research demonstrates that TOD affects empathy, and sleepiness decreases empathy and increases burnout in medical students. Full article

The way in which the circadian clock mechanism develops and decays throughout life is interesting for a number of reasons and may give us insight into the process of aging itself. The Drosophila model has been proven invaluable for the study of the circadian clock and development and aging. Here we review the evidence for how the Drosophila clock develops and changes throughout life, and present a new conceptual model based on the results of our recent work. Firefly luciferase lines faithfully report the output of known clock genes at the central clock level in the brain and peripherally throughout the whole body. Our results show that the clock is functioning in embryogenesis far earlier than previously thought. This central clock in the fly remains robust throughout the life of the animal and only degrades immediately prior to death. However, at the peripheral (non-central oscillator level) the clock shows weakened output as the animal ages, suggesting the possibility of the breakdown in the cohesion of the circadian network. Full article

Although sleep is heritable and conserved across species, sleep duration varies from individual to individual. A shared genetic architecture between sleep duration and other evolutionarily important traits could explain this variability. Learning and memory are critical traits sharing a genetic architecture with sleep. We wanted to know whether learning and memory would be altered in extreme long or short sleepers. We therefore assessed the short-term learning and memory ability of flies from the Sleep Inbred Panel (SIP), a collection of 39 extreme long- and short-sleeping inbred lines of Drosophila. Neither long nor short sleepers had appreciable learning, in contrast to a moderate-sleeping control. We also examined the response of long and short sleepers to enriched social conditions, a paradigm previously shown to induce morphological changes in the brain. While moderate-sleeping control flies had increased daytime sleep and quantifiable increases in brain structures under enriched social conditions, flies of the Sleep Inbred Panel did not display these changes. The SIP thus emerges as an important model for the relationship between sleep and learning and memory. Full article

Excessive daytime sleepiness (EDS) is a common problem in general the Canadian population. It can effect day-to-day activities and is also associated with several health issues. This study aimed to investigate the association between co-morbidities and the prevalence of EDS over a four-year period in adults living in two First Nation communities. Data collected during the First Nations Lung Health Project (FNLHP) conducted in two Cree First Nation communities in Saskatchewan in 2012–2013 (Cycle 1) and 2016 (Cycle 2) were used for this analysis. There were 859 participants aged 18 years and older at baseline (Cycle 1) and 821 participants aged 18 years and older at follow-up (Cycle 2) who completed the interviewer-administered questionnaire. An Epworth Sleepiness Scale (ESS) score > 10 was considered to be abnormal and identified as a case of EDS at both time points. A multilevel logistic regression model using a generalized estimating equations approach was used to analyze the data. The prevalence of EDS at baseline (Cycle 1) was 11.2% (91/815) and 10.0% (80/803) at follow-up (Cycle 2). Based on the predicted model, longitudinal change in the prevalence of EDS was −0.11% for 358 individuals who participated in both cycles. There were 49% males at baseline and 48% males at follow-up. Multivariate regression model results revealed that crowding, shortness of breath, loud snoring, chronic lung disease, depression and gastric reflux were the main significant predictors of EDS. In addition, the interaction between sex and age was significant. Some of the co-morbid conditions were associated with EDS. Therefore, managing such conditions requires considerations in strategies to decrease the prevalence of daytime sleepiness. Full article

Circadian rhythms regulate many physiological and behavioral processes, including sleep, metabolism and cell division, which have a 24-h oscillation pattern. Rhythmicity is generated by a transcriptional–translational feedback loop in individual cells, which are synchronized by the central pacemaker in the brain and external cues. Epidemiological and clinical studies indicate that disruption of these rhythms can increase both tumorigenesis and cancer progression. Environmental changes (shift work, jet lag, exposure to light at night), mutations in circadian regulating genes, and changes to clock gene expression are recognized forms of disruption and are associated with cancer risk and/or cancer progression. Experimental data in animals and cell cultures further supports the role of the cellular circadian clock in coordinating cell division and DNA repair, and disrupted cellular clocks accelerate cancer cell growth. This review will summarize studies linking circadian disruption to cancer biology and explore how such disruptions may be further altered by common characteristics of tumors including hypoxia and acidosis. We will highlight how circadian rhythms might be exploited for cancer drug development, including how delivery of current chemotherapies may be enhanced using chronotherapy. Understanding the role of circadian rhythms in carcinogenesis and tumor progression will enable us to better understand causes of cancer and how to treat them. Full article

We are pleased to present you with this Special Issue of Clocks & Sleep, the abstracts of the 2019 annual meeting of the Swiss Society for Sleep Research, Sleep Medicine, and Chronobiology (SSSSC), which took place in Fribourg, 27 and 28 June [...] Full article