Large-scale data from wearables reveal regional disparities in sleep patterns that persist across age and sex.
ABSTRACT: Prior reports on geographical differences in sleep duration have relied on samples collected at different time points with a variety of subjective instruments. Using sleep data from a total of 553,559 nights from 23,680 Fitbit users (aged 15-80y), we found objective evidence for regional disparities in sleep duration of 32-43 min between Oceanian and East Asian users on weekdays. This was primarily driven by later bedtimes in East Asians. Although users in all countries extended sleep on weekends, East Asians continued to sleep less than their Oceanian counterparts. Women generally slept more than men, and older users slept less than younger users. Reasons for shorter sleep duration in East Asians on both weekdays and weekends, across the lifespan and in both sexes remain to be investigated.
Project description:Objectives:There is increasing awareness about the effects of circadian misalignment on health and work. In the present study, we aimed to investigate the effects of chronotype on academic achievement among medical students. Methods:A cross-sectional comparative study was conducted among 140 medical students (64 who averaged an A grade and 76 who averaged a C grade) completing the clinical phase at the medical college of Omdurman University, Sudan. The participants were asked to sign a written informed consent and to keep a diary detailing their bedtime, wake-up time, sleep latency, and sleep duration during working days and weekends. Then, the participants were invited to respond to a questionnaire. The chronotype was calculated from the mid-sleep time during the weekend and sleep debt. Various sleep parameters were then compared between the two groups. A t-test and logistic regression analysis were used to test the statistical significance. Results:The medical students with average grades were more of the evening chronotype than the students with excellent grades (p < 0.05). Significant differences were found between the two groups regarding weekend bedtime, wake-up time, and sleep duration. In addition, significant differences were evident for weekday bedtime, sleep latency, and wake-up lag between weekdays and weekends. No differences were observed between the two groups during weekday wake-up time and sleep duration, chronotype between gender, and bedtime delay between weekdays and weekends (p > 0.05). Conclusion:Students whose average grade was a C were more likely to have a later bedtimes during weekdays and weekends, sleep more during weekends, and were more evening.
Project description:Limited observational studies have described the relationship between sleep duration and overall diet. The present study investigated the association between sleep duration on weekdays or social jetlag and empirically derived dietary patterns in a nationally representative sample of UK adults, aged 19?64 years old, participating in the 2008?2012 UK National Diet and Nutrition Survey Rolling Programme. Survey members completed between three to four days of dietary records. Sleep duration on weekdays was categorized into tertiles to reflect short, normal, and long sleep duration. Social jetlag was calculated as the difference between sleep duration on weekends and weekdays. The association between sleep duration/social jetlag and dietary patterns, derived by principal components analysis, was assessed by regressing diet on sleep, whilst accounting for the complex survey design and adjusting for relevant confounders. Survey members in the highest tertile of sleep duration had on average a 0.45 (95% Confidence Interval (CI) -0.78, -0.12) lower healthy dietary pattern score, compared to middle tertile (p = 0.007). There was an inverted u-shaped association between social jetlag and the healthy dietary pattern, such that when sleep on weekends exceeded weekday sleep by 1 h 45 min, scores for indicating a healthy dietary pattern declined (p = 0.005). In conclusion, long sleep duration on weekdays and an increased social jetlag are associated with a lower healthy dietary pattern score. Further research is required to address factors influencing dietary patterns in long sleepers.
Project description:STUDY OBJECTIVES:To compare the secular trends of sleep/wake patterns in school-aged children in Hong Kong and Shanghai, two major metropolitan cities in China with two different policies that school start time was delayed in Shanghai, but advanced in Hong Kong in 10 years' time. METHODS:Participants were from two waves of cross-sectional school-based surveys of children aged 6 to 11 years. In Shanghai, 4,339 and 13,795 children participated in the 2005 and 2014 surveys, respectively. In Hong Kong, 6,231 and 4,585 children participated in the 2003 and 2012 surveys, respectively. Parents reported their children's bedtime and wakeup time, and thus sleep duration, short sleep (? 9 hours) and weekend oversleep (difference in sleep duration between weekday and weekend > 2 hours) were determined. RESULTS:Hong Kong children had later bedtime and wakeup time and slept consistently less than their Shanghai counterparts at both survey time points. The shorter sleep duration was particularly marked during weekdays. Over the interval period, weekday sleep duration significantly decreased from 9.2 to 8.9 hours as wakeup time became earlier for Hong Kong children, but increased from 9.4 to 9.6 hours as wakeup time became later for children in Shanghai. Children from both cities slept longer on the weekends. Prevalence of weekend oversleep significantly increased in Hong Kong children, but no interval change was found in Shanghai children. CONCLUSIONS:The findings indicate subcultural differences in sleep/wake patterns in Shanghai and Hong Kong school-aged children. In particular, sleep duration had increased for Shanghai children, but decreased for Hong Kong children over 10 years. The benefits and barriers of delaying school start time for optimizing sleep health in school-aged children should be further explored.
Project description:Improving adolescent sleep health is a national priority for ameliorating health and wellbeing (Healthy People 2020), as the majority of adolescents do not get the minimum recommended amount of 8 h of sleep per night. Prior research has identified sex and ethnoracial disparities in adolescent sleep but has been limited by data availability. National studies have collected reported sleep data, while objective sleep data has been available in community samples only. Using new data from adolescents in the Fragile Families and Child Wellbeing Study, a population-based birth cohort study of children born 1998-2000, we are able to characterize sex and ethnoracial disparities in sleep health in the first national sample of actigraphy-assessed sleep health among adolescents. In cross-sectional analyses, we used linear and logistic regression models to assess sex and ethnoracial disparities in weekday sleep duration, timing, and quality measured using actigraphy collected from 738 adolescents at approximately age 15. We identified sex and ethnoracial group differences in weekday and weekend adolescent sleep duration, with larger disparities on weekends than weekdays. Male adolescents had 27-min shorter nightly sleep durations than females on weeknights. Non-Hispanic black adolescents had 32-min shorter nightly sleep durations than non-Hispanic whites on weekdays and 41-min shorter nightly sleep durations on weekends. While sex disparities persisted after accounting for naps, black-white differences were attenuated by napping such that there was no statistically significant black-white disparity in 24-h sleep on either weekdays or weekends. We did not identify disparities in sleep timing or quality. Future research should investigate the pathways through which these disparities arise, including behavioral and contextual mechanisms.
Project description:BACKGROUND:Sleep disturbances and low-quality diets are prevalent among children in low-income settings, yet the nature of their relationship remains unclear. In particular, whether aspects other than sleep duration, including timing and quality, are associated with dietary patterns has rarely been examined, especially among preschool-aged children. OBJECTIVE:To evaluate whether nightly and total sleep duration, sleep timing, differences in timing and duration from weekdays to weekends, and sleep quality were related to dietary patterns. DESIGN:A cross-sectional analysis of children attending preschool. Parents completed questionnaires about children's sleep habits as well as a semiquantitative food frequency questionnaire. PARTICIPANTS/SETTING:Three hundred fifty-four English-speaking children (49.9% boys) with no serious medical conditions aged 3 to 5 years who were enrolled in Head Start in Michigan (2009-2011) with complete information on sleep and diet. MAIN OUTCOME MEASURES:Dietary pattern scores derived from food frequency questionnaire. STATISTICAL ANALYSES PERFORMED:Principal component analysis was used to identify dietary patterns. Separate linear regression models with dietary pattern scores as the dependent variable and continuous sleep measures as independent variables were used to evaluate associations between sleep and diet, adjusting for sex, age, parent education level, and sleep hygiene. RESULTS:Three dietary patterns were identified: Vegetables, Healthy Proteins, and Sides; Breads and Spreads; and Processed and Fried. Longer average weekend sleep duration and a greater difference in weekend-to-weekday sleep duration was related to lower Vegetables, Healthy Proteins, and Sides pattern scores. Later sleep midpoint during weekdays was related to lower Vegetables, Healthy Proteins, and Sides pattern scores, whereas later sleep midpoint on the weekend was associated with higher Processed and Fried pattern scores. Similarly, a larger weekend-weekday midpoint difference was associated with higher Processed and Fried pattern scores. CONCLUSIONS:Later sleep timing and differences in sleep duration and timing from weekends to weekdays were related to less-optimal dietary pattern scores in young children.
Project description:Sleep may play a role in overweight and obesity in adolescents. The objective of this study is to investigate the relationships between sleep duration and timing and overweight and obesity status in adolescents, with a special emphasis on weekday-weekend difference in sleep characteristics as well as sex-specific relationships. We examined 1,254 U.S. adolescents (12-17 years) self-reported sleep duration, timing, weekday-weekend differences in duration and timing in relation to overweight and obesity. We found an inverse association between sleep duration and overweight and obesity. Compared to 8-9 h of sleep, short sleep (<?7 h) on weekdays was associated with higher odds of overweight and obesity [Odds ratio (95% confidence interval), 1.73 (1.00, 2.97)] in the overall population, while long sleep (10+ h) on weekends was associated with lower odds, but only in males [0.56 (0.34, 0.92)]. We also found that a larger weekday-weekend difference in sleep duration was associated with overweight and obesity in females, but not in males. Specifically, the odds of overweight and obesity were significantly higher among females reporting longer sleep on weekends than weekdays by???2 h [2.31 (1.15, 4.63)] when compared to those reporting little weekday-weekend differences. Sleep timing, or weekday-weekend differences in sleep timing, were not associated with overweight and obesity in the overall population, although we found suggestive evidence linking later weekend sleep with overweight and obesity in females. Our findings support a role of sleep in adolescent obesity and suggest sex-differences in this relationship that warrant future studies.
Project description:BACKGROUND:Inadequate sleep duration, sleep patterns, and sleep quality have been associated with metabolic, circadian, and behavioral changes that promote obesity. Adolescence is a period during which sleep habits change to include less sleep, later bedtimes, and greater bedtime shift (e.g., difference between weekend and weekday bedtime). Thus, sleep may play a role in adolescent obesity and weight-related behaviors. This study assesses sleep duration, quality, and schedules and their relationships to relative weight and body fat percentage as well as diet, physical activity, and screen time in adolescents with overweight/obesity. METHODS:Adolescents between 12 and 17 years old (n?=?186) were weighed and measured, reported typical sleep and wake times on weekdays and weekends, and responded to questionnaires assessing diet, physical activity, and screen time habits. RESULTS:Controlling for sleep duration, later weekend bedtime and greater bedtime shift were associated with greater severity of overweight (??=?0.20; ??=?0.16) and greater screen time use (??=?0.22; ??=?0.2). Later bedtimes on the weekdays and weekends were associated with fewer healthy diet practices (??=?-0.26; ??=?-0.27). In addition, poorer sleep quality was associated with fewer healthy diet habits (??=?-0.21), greater unhealthy diet habits (??=?0.15), and less physical activity (??=?-0.22). Sleep duration was not associated with any weight or weight-related behavior. CONCLUSIONS:Sleep patterns and quality are associated with severity of overweight/obesity and various weight-related behaviors. Promoting a consistent sleep schedule throughout the week may be a worthwhile treatment target to optimize behavioral and weight outcomes in adolescent obesity treatment.
Project description:The goal was to explore the effects of duration and regularity of sleep schedules on BMI and the impact on metabolic regulation in children.Sleep patterns of 308 community-recruited children 4 to 10 years of age were assessed with wrist actigraphs for 1 week in a cross-sectional study, along with BMI assessment. Fasting morning plasma levels of glucose, insulin, lipids, and high-sensitivity C-reactive protein also were measured for a subsample.Children slept 8 hours per night, on average, regardless of their weight categorization. A nonlinear trend between sleep and weight emerged. For obese children, sleep duration was shorter and showed more variability on weekends, compared with school days. For overweight children, a mixed sleep pattern emerged. The presence of high variance in sleep duration or short sleep duration was more likely associated with altered insulin, low-density lipoprotein, and high-sensitivity C-reactive protein plasma levels. Children whose sleep patterns were at the lower end of sleep duration, particularly in the presence of irregular sleep schedules, exhibited the greatest health risk.Obese children were less likely to experience "catch-up" sleep on weekends, and the combination of shorter sleep duration and more-variable sleep patterns was associated with adverse metabolic outcomes. Educational campaigns, aimed at families, regarding longer and more-regular sleep may promote decreases in obesity rates and may improve metabolic dysfunction trends in school-aged children.
Project description:To determine the relationship between napping and cognitive function in preschool-aged children.Daytime napping, nighttime sleep, and cognitive function were assessed in 59 typically developing children aged 3 to 5 years, who were enrolled in full-time childcare. Participants wore an actigraphy watch for 7 days to measure sleep and napping patterns and completed neuropsychological testing emphasizing attention, response control, and vocabulary. Parents of participants completed behavior ratings and sleep logs during the study. Sleep/wake cycles were scored with the Sadeh algorithm.Children who napped more on weekdays were also more likely to nap during weekends. Weekday napping and nighttime sleep were inversely correlated, such that those who napped more slept less at night, although total weekday sleep remained relatively constant. Weekday napping was significantly (negatively) correlated with vocabulary and auditory attention span, and weekday nighttime sleep was positively correlated with vocabulary. Nighttime sleep was also significantly negatively correlated with performance, such that those who slept less at night made more impulsive errors on a computerized go/no-go test.Daytime napping is actually negatively correlated with neurocognitive function in preschoolers. Nighttime sleep seems to be more critical for development of cognitive performance. Cessation of napping may serve as a developmental milestone of brain maturation. Children who nap less do not appear to be sleep deprived, especially if they compensate with increased nighttime sleep. An alternative explanation is that children who sleep less at night are sleep deprived and require a nap. A randomized trial of nap restriction would be the next step in understanding the relationship between napping and neurocognitive performance.
Project description:INTRODUCTION: Electronic devices in the bedroom are broadly linked with poor sleep in adolescents. This study investigated whether there is a dose-response relationship between use of electronic devices (computers, cellphones, televisions and radios) in bed prior to sleep and adolescent sleep patterns. METHODS: Adolescents aged 11-17 yrs (n?=?1,184; 67.6% female) completed an Australia-wide internet survey that examined sleep patterns, sleepiness, sleep disorders, the presence of electronic devices in the bedroom and frequency of use in bed at night. RESULTS: Over 70% of adolescents reported 2 or more electronic devices in their bedroom at night. Use of devices in bed a few nights per week or more was 46.8% cellphone, 38.5% computer, 23.2% TV, and 15.8% radio. Device use had dose-dependent associations with later sleep onset on weekdays (highest-dose computer adjOR ?=?3.75: 99% CI ?=?2.17-6.46; cellphone 2.29: 1.22-4.30) and weekends (computer 3.68: 2.14-6.32; cellphone 3.24: 1.70-6.19; TV 2.32: 1.30-4.14), and later waking on weekdays (computer 2.08: 1.25-3.44; TV 2.31: 1.33-4.02) and weekends (computer 1.99: 1.21-3.26; cellphone 2.33: 1.33-4.08; TV 2.04: 1.18-3.55). Only 'almost every night' computer use (: 2.43: 1.45-4.08) was associated with short weekday sleep duration, and only 'almost every night' cellphone use (2.23: 1.26-3.94) was associated with wake lag (waking later on weekends). CONCLUSIONS: Use of computers, cell-phones and televisions at higher doses was associated with delayed sleep/wake schedules and wake lag, potentially impairing health and educational outcomes.