Search

Summary: Previous research has demonstrated that exposure to light preceding and during sleep is associated with poor sleep, but most research to date has utilized either experimental or cross‐sectional designs. The current study expands upon prior studies by using a microlongitudinal design that examines the night‐to‐night associations between light and sleep health in a diverse sample of adults (pre‐registered at osf.io/k5zgv). US adults aged 18–87 years from two parent studies (N = 124) wore an actiwatch for up to 10 nights. Light variables estimated from actigraphy include both average exposure and time above light threshold of 10 (TALT10) and 40 (TALT40) lux both during sleep and for the 1‐hr preceding sleep. Actigraphy‐based sleep variables included sleep offset, duration, percentage and fragmentation index. Higher average light exposure during sleep was associated with a later sleep‐offset time, lower sleep percentage and higher fragmentation index (all p < 0.01). More minutes of TALT10 during sleep was associated with later sleep timing, lower sleep percentage and higher fragmentation index (all p < 0.01), and greater TALT40 during sleep was associated with lower sleep percentage. Light exposure was not related to sleep duration. In summary, greater light exposure during sleep was related to poorer sleep continuity and later wake time. The lack of association between light and sleep duration may be the result of compensating for sleep disruption by delaying wake time. Multi‐level interventions to consistently reduce light levels during sleep should be considered. [ABSTRACT FROM AUTHOR]

The human circadian system plays a vital role in many physiological processes, and circadian rhythms are found in virtually all tissues and organs. The disruption of circadian rhythms may lead to adverse health outcomes. Evidence from recent population‐based studies was reviewed because they represent real‐world behavior and can be useful in developing future studies to reduce the risk of adverse health conditions, including cardiovascular diseases, obesity, and diabetes mellitus, which may occur because of circadian disruption. An electronic search in PubMed and Web of Science (2012–2022) was performed. Selected articles were based on specific inclusion and exclusion criteria. Five factors that may disrupt circadian rhythm alignment are discussed: shift work, late chronotype, late sleep timing, sleep irregularity, and late meal timing. Evidence from observational studies of these circadian disruptors suggests potential detrimental effects on cardiometabolic health, including higher BMI/obesity, higher blood pressure, greater dyslipidemia, greater inflammation, and diabetes. Future research should identify the specific underlying pathways in order to mitigate the health consequences of shift work. Furthermore, optimal sleep and mealtimes for metabolic health can be explored in intervention studies. Lastly, it is important that the timing of external environmental cues (such as light) and behaviors that influence circadian rhythms are managed. [ABSTRACT FROM AUTHOR]

Non‐communicable diseases, including diabetes, are partly responsible for the deceleration of improvements of life expectancy in many countries. Diabetes is also associated with sleep disturbances. Our aim was to determine whether sleep disturbances, particularly in people with diabetes, were associated with increased mortality risk. Data from the UK Biobank were analysed (n = 487,728, mean follow‐up time = 8.9 years). The primary exposure was sleep disturbances, assessed through the question: Do you have trouble falling asleep at night or do you wake up in the middle of the night? The primary outcome was mortality. We also dichotomized sleep disturbances into "never/sometimes" versus "usually" (frequently), and combined with the presence/absence of diabetes: 24.2% of participants reported "never/rarely" experiencing sleep disturbances, 47.8% "sometimes" and 28.0% "usually". In age‐ and sex‐adjusted models, frequent sleep disturbances were associated with an increased risk of all‐cause mortality (hazard ratio [HR], 1.31; 95% confidence interval [CI], 1.26–1.37), which remained significant in the fully adjusted model (HR 1.13, 95% CI 1.09–1.18). The presence of both diabetes and frequent sleep disturbances was associated with greater risk of all‐cause mortality than either condition alone. In the fully adjusted model, the hazard ratio for all‐cause mortality was 1.11 (95% CI, 1.07–1.15) for frequent sleep disturbances alone, 1.67 (95% CI, 1.57–1.76) for diabetes alone and 1.87 for both (95% CI, 1.75–2.01). Frequent sleep disturbances (experienced by more than one quarter of the sample) were associated with increased risk of all‐cause mortality. Mortality risk was highest in those with both diabetes and frequent sleep disturbances. Complaints of difficulty falling or staying asleep merit attention by physicians. [ABSTRACT FROM AUTHOR]

Studying communities at different stages of urbanisation and industrialisation can teach us how timing and intensity of light affect the circadian clock under real‐life conditions. We have previously described a strong tendency towards morningness in the Baependi Heart Study, located in a small rural town in Brazil. Here, we tested the hypothesis that this morningness tendency is associated with early circadian phase based on objective measurements (as determined by dim light melatonin onset, DLMO, and activity) and light exposure. We also analysed how well the previously collected chronotype questionnaire data were able to predict these DLMO values. The average DLMO observed in 73 participants (40 female) was 20:03 ± 01:21, SD, with an earlier average onset in men (19:38 ± 01:16) than in women (20:24 ± 01:21; P ≤.01). However, men presented larger phase angle between DLMO and sleep onset time as measured by actigraphy (4.11 hours vs 3.16 hours; P ≤.01). Correlational analysis indicated associations between light exposure, activity rhythms and DLMO, such that early DLMO was observed in participants with higher exposure to light, higher activity and earlier light exposure. The strongest significant predictor of DLMO was morningness‐eveningness questionnaire (MEQ) (beta=−0.35, P ≤.05), followed by age (beta = −0.47, P ≤.01). Sex, light exposure and variables derived from the Munich chronotype questionnaire were not significant predictors. Our observations demonstrate that both early sleep patterns and earlier circadian phase have been retained in this small rural town in spite of availability of electrification, in contrast to metropolitan postindustrial areas. [ABSTRACT FROM AUTHOR]

Summary: Physiological evidence suggests that sleep modulates kidney function. Our objective was to examine the cross‐sectional association between kidney function and objectively‐estimated habitual sleep duration, quality and timing in a cohort of patients with mild to moderate chronic kidney disease. This study involved two US clinical centers of the Chronic Renal Insufficiency Cohort (CRIC) study, including 432 participants in a CRIC ancillary sleep study. Habitual sleep duration, quality and timing were measured using wrist actigraphy for 5–7 days. Validated sleep questionnaires assessed subjective sleep quality, daytime sleepiness and risk of sleep apnea. Kidney function was assessed with the estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration equation, and the urinary protein to creatinine ratio. Lower estimated glomerular filtration rate was associated with shorter sleep duration (−1.1 mL min−1 1.73 m−2 per hour less sleep, P = 0.03), greater sleep fragmentation (−2.6 mL min−1 1.73 m−2 per 10% higher fragmentation, P < 0.001) and later timing of sleep (−0.9 mL min−1 1.73 m−2 per hour later, P = 0.05). Higher protein to creatinine ratio was also associated with greater sleep fragmentation (approximately 28% higher per 10% higher fragmentation, P < 0.001). Subjective sleep quality, sleepiness and persistent snoring were not associated with estimated glomerular filtration rate or protein to creatinine ratio. Thus, worse objective sleep quality was associated with lower estimated glomerular filtration rate and higher protein to creatinine ratio. Shorter sleep duration and later sleep timing were also associated with lower estimated glomerular filtration rate. Physicians treating patients with chronic kidney disease should consider inquiring about sleep and possibly sending for clinical sleep assessment. Longitudinal and interventional trials are needed to understand causal direction. [ABSTRACT FROM AUTHOR]

Sleep symptoms are associated with weight gain and cardiometabolic disease. The potential role of diet has been largely unexplored. Data from the 2007-2008 National Health and Nutrition Examination Survey ( NHANES) were used ( n = 4552) to determine which nutrients were associated with sleep symptoms in a nationally representative sample. Survey items assessed difficulty falling asleep, sleep maintenance difficulties, non-restorative sleep and daytime sleepiness. Analyses were adjusted for energy intake, other dietary factors, exercise, body mass index ( BMI) and sociodemographics. Population-weighted, logistic regression, with backwards-stepwise selection, examined which nutrients were associated with sleep symptoms. Odds ratios ( ORs) reflect the difference in odds of sleep symptoms associated with a doubling in nutrient. Nutrients that were associated independently with difficulty falling asleep included (in order): alpha-carotene ( OR = 0.96), selenium ( OR = 0.80), dodecanoic acid ( OR = 0.91), calcium ( OR = 0.83) and hexadecanoic acid ( OR = 1.10). Nutrients that were associated independently with sleep maintenance difficulties included: salt ( OR = 1.19), butanoic acid (0.81), carbohydrate ( OR = 0.71), dodecanoic acid ( OR = 0.90), vitamin D ( OR = 0.84), lycopene ( OR = 0.98), hexanoic acid ( OR = 1.25) and moisture ( OR = 1.27). Nutrients that were associated independently with non-restorative sleep included butanoic acid ( OR = 1.09), calcium ( OR = 0.81), vitamin C ( OR = 0.92), water ( OR = 0.98), moisture ( OR = 1.41) and cholesterol ( OR = 1.10). Nutrients that were associated independently with sleepiness included: moisture ( OR = 1.20), theobromine ( OR = 1.04), potassium ( OR = 0.70) and water ( OR = 0.97). These results suggest novel associations between sleep symptoms and diet/metabolism, potentially explaining associations between sleep and cardiometabolic diseases. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives Sleep comprises one-third of one's life, yet little is known about sleep in developing countries. Furthermore, many studies in industrialized countries have reported that sleep duration and quality decline with aging, but whether this association persists globally is unknown. This study's objectives were to characterize sleep in a community without electricity in Haiti and to examine associations between measures of sleep and age. Methods Fifty-eight Haiti residents (50% women) in four age groups, 18-30, 31-50, 51-64, and ≥65 years participated. Three days of wrist actigraphy were used to estimate sleep patterns. Results Mean (standard deviation) values of sleep measures were: 20:57 (0:40) for sleep onset, 4:54 (0:43) for sleep end, 9.3 (1.2) h for time in bed, 7.0 (1.0) h for sleep duration, 54 (24) min awake after sleep onset, and 88.7 (5.4)% for sleep maintenance (percentage of sleep period actually spent sleeping). There were no significant differences in the sleep measures between men and women. Regression analyses adjusting for sex, household size, and number of people sleeping in the same room indicated that only sleep fragmentation differed by age group. Specifically, mean fragmentation was higher in the youngest age group than all other age groups, which did not differ from one another. Conclusions Average time in bed in this Haitian sample was greater than previously reported for industrialized countries like the United States (9.3 versus. 7-8 h);, however, actual sleep duration averaged only 7 h. No age-related decline in sleep duration or quality was observed in Haiti. Am. J. Hum. Biol. 26:80-86, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The prevalence of obesity is increasing rapidly worldwide, which is cause for concern because obesity increases the risk of cardiovascular disease and diabetes, reduces life expectancy, and impairs quality of life. A better understanding of the risk factors for obesity is therefore a critical global health concern, and human biologists can play an important role in identifying these risk factors in various populations. The objective of this review is to present the evidence that inadequate sleep may be a novel risk factor associated with increased vulnerability to obesity and associated cardiometabolic disease. Experimental studies have found that short-term sleep restriction is associated with impaired glucose metabolism, dysregulation of appetite, and increased blood pressure. Observational studies have observed cross-sectional associations between short sleep duration (generally <6 h per night) and increased body mass index or obesity, prevalent diabetes, and prevalent hypertension. Some studies also reported an association between self-reported long sleep duration (generally >8 h per night) and cardiometabolic disease. A few prospective studies have found a significant increased risk of weight gain, incident diabetes, and incident hypertension associated with inadequate sleep. Given the potential link between inadequate sleep and obesity, a critical next step is to identify the social, cultural, and environmental determinants of sleep, which would help to identify vulnerable populations. Future human biology research should consider variation in sleep characteristics among different populations and determine whether the associations between sleep and obesity observed in Western populations persist elsewhere. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Summary Slow-wave sleep has been associated with several physiological phenomena, including glucose metabolism, sympathetic nervous system activity, hormonal secretion and blood pressure regulation. The aim of these analyses was to determine which sociodemographic and medical factors were associated with slow-wave sleep duration in a large clinical sample. We conducted cross-sectional analysis of clinical data from 1019 consecutive adults over a 10-month period who had their first in-laboratory polysomnogram for suspicion of obstructive sleep apnea. Patients either underwent in-laboratory full-night polysomnogram followed by full-night continuous positive airway pressure titration or split-night polysomnogram. Patients also completed questionnaires to assess race, education, marital status and medical co-morbidities. A multiple linear regression model that predicted the natural log of slow-wave sleep in minutes indicated that African Americans had approximately 48% less slow-wave sleep than non-African Americans. Increasing age and male gender were also associated with less slow-wave sleep. Overweight and obese individuals had significantly less slow-wave sleep than those not overweight, even after adjustment for obstructive sleep apnea severity. Finally, those with severe obstructive sleep apnea had significantly less slow-wave sleep than those with less severe obstructive sleep apnea even after adjustment for obesity. Results remained unchanged when patients who had a split-night polysomnogram were excluded. We observed less slow-wave sleep in African Americans, a group at increased risk of diabetes and hypertension compared with Caucasians, and in those who are overweight and obese and those with severe obstructive sleep apnea. Future research needs to explore potential reasons for reduced slow-wave sleep in these individuals. [ABSTRACT FROM AUTHOR]

The article focuses on a study which analyzed the associations between sleep duration and body size among Cuban-Americans, Mexican-Americans, and Puerto Ricans. The study found an average sleep duration of 7.3 to 7.7 hours, with Mexican-Americans having the shortest sleep duration and larger body size. Study authors concluded that their findings underscore the relevance of examining the factors that are associated with obesity in different ethnic groups.

During the past few decades, sleep curtailment has become a very common in industrialized countries. This trend for shorter sleep duration has developed over the same time period as the dramatic increase in the prevalence of obesity and diabetes. Evidence is rapidly accumulating to indicate that chronic partial sleep loss may increase the risk of obesity and diabetes. Laboratory studies in healthy volunteers have shown that experimental sleep restriction is associated with an adverse impact on glucose homeostasis. Insulin sensitivity decreases rapidly and markedly without adequate compensation in beta cell function, resulting in an elevated risk of diabetes. Prospective epidemiologic studies in both children and adults are consistent with a causative role of short sleep in the increased risk of diabetes. Sleep curtailment is also associated with a dysregulation of the neuroendocrine control of appetite, with a reduction of the satiety factor, leptin, and an increase in the hunger-promoting hormone, ghrelin. Thus, sleep loss may alter the ability of leptin and ghrelin to accurately signal caloric need, acting in concert to produce an internal misperception of insufficient energy availability. The adverse impact of sleep deprivation on appetite regulation is likely to be driven by increased activity in neuronal populations expressing the excitatory peptides orexins that promote both waking and feeding. Consistent with the laboratory evidence, multiple epidemiologic studies have shown an association between short sleep and higher body mass index after controlling for a variety of possible confounders. [ABSTRACT FROM AUTHOR]

Previous research in lean subjects has found lower leptin levels associated with shorter sleep duration. Since leptin levels are higher and some of the actions of leptin are impaired in obese individuals, one cannot assume that sleep will be similarly associated with leptin in obese individuals. The aim of this paper was to examine the cross-sectional association between habitual sleep duration and quality and plasma leptin levels in a sample of 80 obese men and premenopausal women aged 18-50 years. Leptin levels (ng/ml) were assayed on a fasting blood sample taken in the morning. We calculated a relative leptin level by dividing leptin by body fat percentage. Sleep duration and sleep efficiency were measured by 2 weeks of wrist actigraphy and respiratory disturbance index (RDI), a measure of sleep disordered breathing, was assessed by a portable screening device on a single night. Mean leptin levels and body fat percentage were higher in women than men (P < 0.001), however, mean RDI was higher in men (P = 0.01). There were no significant associations between relative leptin level and any of the sleep measures, including sleep duration, sleep efficiency, and sleep disordered breathing. There was also no difference between men and women in the association between sleep and leptin. In conclusion, contrary to what has been reported in other studies, measures of sleep duration and quality were not associated with leptin levels in our sample of obese adults. [ABSTRACT FROM AUTHOR]

Summary Gender and age are well‐established determinants of health and sleep health that influence overall health, which also often varies by gender and age. Sleep architecture is an important component of sleep health. The goal of this analysis was to examine whether associations between age and sleep stages differ by gender in the absence of moderate–severe obstructive sleep apnea (OSA) in a rural setting in Brazil. This study conducted polysomnography recordings in the Baependi Heart Study, a cohort of Brazilian adults. Our sample included 584 women and 309 men whose apnea–hypopnea index was ≤15 events/h. We used splines to distinguish non‐linear associations between age, total sleep time, wake after sleep onset (WASO), N2, N3, and rapid‐eye‐movement sleep. The mean (standard deviation; range) age was 47 (14; 18–89) years. All sleep outcomes were associated with age. Compared to men, women had more N3 sleep and less WASO after adjusting for age. Model‐based comparisons between genders at specific ages showed statistically higher mean WASO for men at ages 60 (+13.6 min) and 70 years (+19.5 min) and less N3 for men at ages 50 (−13.2 min), 60 (−19.0 min), and 70 years (−19.5 min) but no differences at 20, 30, 40 or 80 years. The other sleep measures did not differ by gender at any age. Thus, even in the absence of moderate–severe OSA, sleep architecture was associated with age across adulthood, and there were gender differences in WASO and N3 at older ages in this rural community. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented which is concerned with objective sleep duration and quality in hospitalized older adults and its association with blood pressure and mood.

A letter to the editor is presented in response to the article "No effect of 8-week time in bed restriction on glucose tolerance in older long sleepers," published in a previous issue, is presented.

Many hormones play important roles in both pubertal development and sleep regulation. Because of the possible consequences of impaired sleep, including impaired health and cognition, it is important to examine whether an association between pubertal stage and sleep exists. The aim of this analysis is to examine the association between sleep and adolescent growth and developmental stage in a large sample of adolescents ages 12-16 years from a nationally representative longitudinal study. This analysis used the public-use data set of the National Longitudinal Study of Adolescent Health, an extensive survey of health and behavior among adolescents in the United States. The study included two interviews approximately 1 year apart. Pubertal development, sleep variables, and height are self-reported. Pubertal development scores were calculated by summing responses to three questions for each sex. The sleep variables include sleep duration, frequent insomnia (once/week or more), frequently waking tired (once/week or more), and insufficient sleep. The results indicate a sex difference in the association between sleep problems and pubertal development. Among females, there was a significant increase in sleep problems with increasing pubertal development score, but not among males. The negative association between sleep duration and pubertal development score, however, was significant in both males and females. There is no association between sleep duration and height velocity (inches/year) in this sample. The results, which are based on a large sample size, warrant further examination with more objective measures into the association between sleep and growth and development among adolescents., (Copyright 2005 Wiley-Liss, Inc)