Sleep duration and obesity in a population-based study

Clinical heterogeneity of sleep quality, emotional and behavioral characteristics, and eating habits in adolescents with obesity: A cluster analysis

This study aims to examine the role of sleep quality, emotional and behavioral characteristics, and eating behavior in adolescents with obesity by means of cluster analysis. One hundred ninety-four adolescents (78 girls, 116 boys) aged 12-17 (mean 14.3 ± 2.7) with obesity (ICD-10 code E 66.0) entered the study. The Adolescent Sleep Wake Scale was used to evaluate sleep quality. The Achenbach Youth Self-Report for Ages 11-18 questionnaire was used to evaluate emotional and behavioral disturbances. The Dutch Eating Behavior Questionnaire was used to assess maladaptive eating. k-Means cluster analysis was used to clarify heterogeneity. Four clusters were identified: the first included anxious, depressed, socially withdrawn adolescents with thought problems and somatic complaints, non-aggressive, obedient, and having mean values on the sleep quality scale, inclined to restrict their food consumption. The second consisted of rule-breaking youngsters with poor sleep quality, reluctant to restrict their food consumption. The third comprised subjects with the highest values on the sleep quality and lowest values on emotional and behavioral problems, aimed at restricting food consumption. The fourth comprised adolescents with obvious signs of emotional disorders, poorest sleep quality, disinhibited behavior, and emotional and external eating. No statistically significant difference was found between the clusters in sex distribution. Patient allocation to the second or fourth cluster was associated with significantly higher body mass index values, as opposed to the reference third cluster.    Conclusion: There is significant variation in teenagers with obesity who have divergent psychological profiles, which should be taken into account. What is Known: • Patients with obesity present with different clinical characteristics. What is New: • Adolescents with obesity may be partitioned into clusters described in terms of emotional, behavioral patterns, including sleep characteristics, and maladaptive eating habits.

Sleep duration, sleep quality and the risk of being obese: Evidence from the Australian panel survey

BACKGROUND

Sleep difficulty is an unmet public health concern affecting a vast proportion of the world's population. Poor sleep duration (short or long sleep length) and quality affect more than half of older people. Sleep difficulty is associated with negative health outcomes such as obesity and reduced longevity. We aimed to assess whether poor sleep duration and quality are significant risk factors for obesity in adults aged 15 and over in Australia by examining a nationally representative panel data.

METHODS

We used three waves (waves 13, 17, and 21) of the nationally representative Household, Income and Labour Dynamics in Australia (HILDA) survey data. The study applied generalized estimating equations (GEE) logistic regression model to assess the relationship between sleep duration and quality with obesity.

RESULTS

The study found that the odds of being obese was significantly higher amongst the study participants with poor sleep duration (adjusted odds ratio [aOR]: 1.24, 95% confidence interval [CI]: 1.16-1.32) and poor sleep quality (aOR: 1.29, 95% CI: 1.02-1.38) compared with their counterparts who had good sleep duration and quality, respectively.

CONCLUSION

Having short or long sleep at night and poor sleep quality are associated with an increased risk of obesity. Obesity poses a significant threat to the health of Australian adults. Enacting policies that raise public awareness of the significance of good sleep hygiene and encouraging healthy sleeping habits should be considered to address the alarming rise in the obesity rate.

Association between vasomotor symptom frequency and weight gain in the Study of Women's Health Across the Nation

OBJECTIVE

The menopause transition is associated with weight gain in women. We examined whether changes in vasomotor symptom (VMS) frequency precede weight changes.

METHODS

This longitudinal retrospective analysis included data from the multisite, multiethnic Study of Women's Health Across the Nation. Women in premenopause or perimenopause aged 42 to 52 years at baseline self-reported VMS frequency (hot flashes/night sweats) and sleep problems at up to 10 annual visits. Menopause status, weight, body mass index, and waist circumference were compared across visits. The primary objective was to measure the association between VMS frequency and weight gain using a lagged approach with first-difference regression models. Secondary objectives were to statistically quantify mediation by sleep problems and moderation by menopause status and explore the association between cumulative, 10-year VMS exposure and long-term weight gain.

RESULTS

The primary analysis sample included 2,361 participants (12,030 visits; 1995-2008). Increased VMS frequency across visits was associated with subsequently increased weight (0.24 kg), body mass index (0.08 kg/m 2 ), and waist circumference (0.20 cm). Cumulative exposure to a high frequency of VMS (≥6 d/2 wk) over 10 consecutive annual visits was associated with increases in weight measures, including a 3.0-cm increase in waist circumference. Contemporaneous sleep problems mediated no more than 27% of waist circumference increases. Menopause status was not a consistent moderator.

CONCLUSIONS

This study demonstrates that increases in VMS, onset of a high frequency of VMS, and persistent VMS symptoms over time may precede weight gain in women.

[Sleep quality, emotional and behavioral disturbances, and eating behavior in adolescents with obesity: a network analysis-based model]

OBJECTIVE

To attempt to identify persistent associations between sleep quality, symptoms of emotional and behavioral disturbances, and characteristics of eating behavior in obese adolescents based on a network analysis.

MATERIAL AND METHODS

The study included 194 adolescents, aged 12-17 years (76 girls, 118 boys), with a confirmed diagnosis of obesity due to excess calories (ICD-10 code E66.0). Sleep quality was studied on the basis of the Adolescent Sleep Wake Scale (ASWS), emotional and behavioral disturbances were assessed with the Achenbach Youth Self-Report for Ages 11-18 (YSR), eating behavior - with the Dutch Eating Behavior Questionnaire (DEBQ). Network analysis was used to identify the most significant and stable associations between the studied indicators.

RESULTS

The association of poor sleep quality with manifestations of disinhibited behavior in the form of violations of the rules of behavior, aggressiveness, and impaired attention was revealed. Positive correlations between the manifestations of disinhibited behavior (primarily, rule-breaking behavior) and emotional eating behavior, which, in turn, had a positive relationship with external and a negative relationship with restrictive eating behavior, were noted. The disinhibited adolescent behavior is linked with uncontrolled food intake, which can contribute to the development of obesity.

CONCLUSION

Impaired sleep quality, symptoms of emotional and behavioral disorders, and eating disorders in obese adolescents present a stable and specific clinical pattern that should be taken into account when justifying therapy.

Sleep and cardiometabolic health in children and adults: examining sleep as a component of the 24-h day

STUDY OBJECTIVES

Sleep, physical activity and sedentary time are all known to play a role in cardiometabolic health. Compositional data analysis (CoDA) enables us to examine associations between 24-h use of time and health outcomes.

METHODS

Data were collected in the Child Health CheckPoint study, a one-off national population-cohort study conducted between February 2015 and March 2016. Wrist-worn actigraphy monitors (GENEActiv Original, Cambs, UK) were used to measure activity behaviours (sleep, physical activity and sedentary time) and sleep characteristics (sleep variability, midsleep, efficiency). CoDA was applied to determine the association between 24-h use of time and cardiometabolic risk markers (blood pressure; body mass index; apolipoprotein B/A1; glycoprotein acetyls; and composite metabolic syndrome score). Substitution modelling (one-for-remaining and one-for-one) examined the associations of reallocating sleep time with other activity behaviours.

RESULTS

Data were available for 1073 Australian children aged 11-12 years (50% male) and 1337 adults (13% male). Strong association was found between 24-h use of time and all cardiometabolic health outcomes. Longer sleep was associated with more favourable cardiovascular health. Sleep characteristics other than duration (efficiency, timing, variability) were weakly and inconsistently associated with outcomes. Reallocating time from sleep to moderate-vigorous physical activity (MVPA) had favourable associations with cardiometabolic health, but reallocating from sleep to sedentary time was associated with less favourable cardiometabolic health.

CONCLUSION

The 24-h activity composition is strongly associated with cardiometabolic health in children and adults. Days with more sleep and MVPA are associated with improved cardiometabolic health.

The relationship between sleep duration and health status in Qatar’s population

Knowledge of sleep duration correlates is limited to developed countries with a lack of studies in the Eastern Mediterranean Region (EMR). Qatar is a rapidly developing country in the EMR with three distinct population groups: Qatari nationals (QNs) or natives; higher income white-collar expatriates (WCEs), and blue-collar workers (BCEs) who are mostly male laborers from South Asia. The aim of this study was to explore the association between sleep duration, chronic health conditions, important lifestyle variables, and sociodemographic characteristics in a representative sample of Qatar’s general population. A total of 2523 surveys were administered over the phone and a final sample of 2500 was retained. The overall prevalence of sleeping < 7hrs was observed at 54%, while 42% of respondents reported sleeping 7–8hrs and 4% reported sleeping > 8hrs. Qatar’s population exhibited low prevalence of normal sleep duration and high prevalence of short sleep duration. Participants who reported the poorest health status had increased odds of sleeping < 7hrs (OR 1.38, P ​= ​0.04) compared with those who reported good health after adjustment for covariates. Additionally, participants with two or more diagnosed illnesses had higher odds of sleeping < 7hrs (OR 1.58, P ​= ​0.02) compared to healthy participants. An increase in odds of sleeping < 7hrs was also observed in participants with obesity (OR 1.58, P ​= ​0.02). Qatar’s population exhibited high prevalence of short sleep duration, which was significantly associated with poor rated health, obesity, and chronic illness independent of age, gender, or social class.

•

Our findings supported a high prevalence of short sleepers and low prevalence of long sleepers.

•

Qatar exhibited one of the lowest prevalence of normal sleep duration compared to other countries.

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Short sleep duration was associated with poor rated health, obesity, and chronic illness but not depression.

Municipal Residence Level of Long-Term PM10 Exposure Associated with Obesity among Young Adults in Seoul, Korea

BACKGROUND

long-term effects of ambient pollutants used to be defined in cohort studies using biomarkers. Health effects on young adults from long-term exposure to particulate matters (PM) in residential ambiance have received less attention.

METHODS

using the data of population-representative aged 19-29 in Seoul, the relationship between obesity and PM10 levels of the living district was examined. We defined obesity as Body Mass Index (BMI) 25 kg/m2 and more. Survey logistic regression was conducted according to individual residence periods in the current municipality. Individual characteristics were adjusted overall and were age-specific; aged 19-24 and 25-29.

RESULTS

study population was 3655 (1680 (46%) men and 1933 aged 19-24 (52.9%)) individuals. Relationship between length of residence in municipalities with a greater level of PM10 from 2001-2005 and obesity was increased over the residing period; 10 years ≤ (odds ratio (OR) 1.071, 95% confidence interval (CI) 0.969-1.185), 15 years ≤ (1.120, 1.006-1.247), and 20 years ≤ (1.158, 1.034-1.297) in aged 19-29. Age-specific effects showed slight differences.

CONCLUSIONS

Although PM10 levels are currently decreasing, higher levels of PM10 exposure in the residential area during the earlier lifetime may contribute to obesity increase among young adults.

Patterns and correlates of sleep duration in the Southern cohort community study

OBJECTIVE

To investigate whether race (African American (AA) and white) is associated with sleep duration among adults from low socioeconomic (SES) strata and whether SES status, lifestyle behaviors, or health conditions are associated with sleep duration within race-sex groups.

METHODS

This cross-sectional study includes 78,549 participants from the Southern Community Cohort Study (SCCS). Averaged daily sleep duration was assessed by weighted averages of self-reported sleep duration on weekdays and weekends. Adjusted odds ratios (ORs) of very short (<5 h/day), short (5-6 h/day), and long sleep (≥9 h/day) associated with pre-selected risk factors in each race-sex group were determined by multinomial logistic models.

RESULTS

The prevalence of very short and short sleep was similar among AAs (6.2% and 29.1%) and whites (6.5% and 29.1%). Long sleep was considerably more prevalent among AAs (19.3%) than whites (13.0%). Very short sleep was associated with lower education and family income, with stronger associations among whites. Higher physical activity levels significantly decreased odds for both very short (OR = 0.80) and long sleep (OR = 0.78). Smoking, alcohol use, and dietary intake were not associated with sleep duration. Regardless of race or sex, very short, short, and long sleep were significantly associated with self-reported health conditions, especially depression (ORs were 2.06, 1.33, and 1.38, respectively).

CONCLUSIONS

Sleep duration patterns differed between AAs and whites from the underrepresented SCCS population with low SES. Sleep duration was associated with several socioeconomic, health behaviors, and health conditions depending on race and sex.

Association Between Sleep and Obesity in African Americans in the Jackson Heart Study

BACKGROUND

In the United States, data from the National Health and Nutrition Examination Survey suggest that 68% of adults are overweight and obese. Obesity has been shown in previous cross-sectional and longitudinal studies to be influenced by short sleep duration, which can lead to unregulated appetite, excessive eating during awake time, and decreased energy expenditure.

OBJECTIVE

To examine the associations among sleep duration, sleep quality, body mass index (BMI), and waist circumference (WC) in African Americans.

METHODS

The sample included participants in the Jackson Heart Study. During a clinic visit, the sleep habits of participants were recorded via a sleep history questionnaire, and BMI and WC measurements were also recorded. Multivariate analysis was used to examine the associations among sleep duration, sleep quality, general obesity (measured by BMI), and abdominal obesity (measured by WC).

RESULTS

The authors studied participants who provided data for the variables of interest (N=3778; 1363 men and 2415 women). Of all participants, 3317 (87.8%) were overweight, and 2149 (56.9%) were obese. The mean (SD) BMI was 32.1 (7.2) kg/m2, and the mean (SD) WC was 103.3 (16.0) cm. Mean sleep duration was 6.3 (1.4) hours for men and 6.4 (1.5) hours for women. Among the men, a significant negative relationship was found between sleep duration and body composition: longer sleep was associated with lower BMI levels but negatively associated with WC in men (β=-1.06; P<.01)]. Sleep quality was positively associated with WC in men (β=1.20; P<.01) and women (β=0.61; P<.05).

CONCLUSIONS

This study's findings highlight the high rate of overweight and obesity among participants in the Jackson Heart Study. About one-fourth of the participants described themselves as enjoying ideal health. In men, longer sleep duration was associated with lower BMI levels and lower WC; in both men and women, good sleep quality was associated with lower WC. However, more research is needed to examine sleep and body composition as risk factors for disease development in African Americans.

The Role of Time Use Behaviors in the Risk of Obesity among Low-Income Mothers

OBJECTIVES

Childrearing responsibilities create additional demands on women's time and effort, especially in low-income families. We explore whether childrearing demands and differences in time use increase the risk of overweight and obesity for women in different income brackets.

METHODS

We use data for women ages 18-55 years from the 2006-2008 and 2014-2015 American Time Use Surveys (N = 17,914). We predict whether women engage in particular activities using logistic regression and, among those who do particular activities, we predict the minutes spent in various activities using ordinary least squares models. We also predict women's risk of overweight or obesity using logistic regression. All models examine conditional relationships between income level and motherhood status.

RESULTS

Replicating prior research, we find a greater risk of overweight and obesity for mothers with low (odds ratio, 1.66; p < .001) and subpoverty (odds ratio, 1.93; p < .001) incomes compared with mothers with moderate/upper incomes and all child-free women. Motherhood and income status jointly predict women's time use, but including these time use behaviors in models of overweight and obesity does not attenuate the significantly higher risks for mothers with low and subpoverty incomes.

CONCLUSIONS

Mothers experiencing economic hardship are at greater risk of overweight and obesity relative to other women. Additional research is warranted, however, because differences in time use do not explain this important health disparity.

Chronic Noise Exposure and Adiposity: A Systematic Review and Meta-analysis

CONTEXT

Noise is a key environmental stressor affecting millions of people worldwide on a daily basis. Chronic exposure to noise may elevate the risk of adiposity through sleep deprivation and heightened stress level.

EVIDENCE ACQUISITION

A literature search was conducted in the PubMed, Web of Science, and Cochrane Library for articles published until February 20, 2018, that assessed the relationship between noise and adiposity. A standardized data extraction form was used to collect methodologic and outcome variables from each included study.

EVIDENCE SYNTHESIS

Eleven studies were identified, among which seven reported a positive association between chronic exposure to noise and adiposity. Compared with their counterparts exposed to a lower noise level, adults chronically exposed to a noise level above 55-60 dBA were associated with a higher waist circumference by 7.5 mm per year (95% CI=3.6, 11.4, I2=0.0%). An increase in chronic exposure to noise by 10 dBA was found to be associated with a higher waist circumference by 7.0 mm per year (95% CI=2.5, 11.6, I2=93.9%) in the random effect model but not the inverse variance heterogeneity model. Chronic noise exposure was not found to be associated with BMI.

CONCLUSIONS

Noise tends to be positively associated with waist circumference but not BMI in adults, but current evidence remains limited. Future studies should assess the impact of noise on adiposity in alternative settings and across population subgroups and geographic areas, examine different sources of noise, and elucidate the biomedical and psychosocial pathways linking noise to adiposity.

Associations Among Sleep, Body Mass Index, Waist Circumference, and Risk of Type 2 Diabetes Among U.S. Childbearing-Age Women: National Health and Nutrition Examination Survey

BACKGROUND

Women of childbearing age (18-44 years) present an important group for understanding sleep, but few studies have focused on this population. No study has investigated the associations among sleep, overweight/obesity, and risk of type 2 diabetes among childbearing-age women in the National Health and Nutrition Examination Survey (NHANES).

METHODS

Data were from NHANES, 2005-2008. The study population consisted of 18-44 year old women. Pregnant women and those diagnosed with sleep disorders were excluded. Sleep duration and quality were self-reported. Body mass index (BMI), waist circumference (WC) measurements, and a 2-hour 75 g oral glucose tolerance test (OGTT) were performed by trained NHANES staff. An unadjusted linear regression analysis; a second adjusted for demographics only (partially adjusted model); and a third adjusted for demographics and variables associated with overweight/obesity and diabetes (fully adjusted model) were computed to assess associations among sleep duration/quality and BMI, WC, and 2-hour OGTT.

RESULTS

Total sample consisted of 2388 childbearing-age women. Only sleep duration was significantly associated with BMI and WC in the unadjusted and partially adjusted models, but was no longer significant in the fully adjusted model. Neither sleep duration nor quality was significantly associated with 2-hour OGTT in any of the models.

CONCLUSIONS

Targeting sleep duration and sleep quality alone would not likely contribute to significantly lower BMI, WC, or risk of type 2 diabetes in US childbearing-age women. Additional studies, especially longitudinal ones using objective measures of sleep, are needed to confirm these findings.

Mind-Body Therapies for African-American Women at Risk for Cardiometabolic Disease: A Systematic Review

Background

A major determinant in cardiometabolic health is metabolic syndrome (MetS), a cluster of symptoms that portend the development of cardiovascular disease (CVD). As mind-body therapies are thought to help in lowering physiological and environmental CVD risk factors including blood pressure and psychological stress, they may also be beneficial for the primary prevention of CVD.

Objectives

To synthesize and summarize existing knowledge on the effectiveness of mind-body therapies on MetS outcomes in African-American (AA) women, a US subpopulation at high risk for CVD.

Search Methods

A systematic search of eight databases was conducted in order to identify published papers addressing the topic. We included trials involving AA adult women, ages 18–64, and we included RCTs that involved multifactorial interventions. Outcomes of interest were MetS, chronic disease, and CVD risk factors (blood pressure, blood lipids, blood glucose, BMI, waist circumference, and mental health domains). Two authors independently selected trials for inclusion, extracted data, and assessed risks of bias.

Main Results

We identified five trials for inclusion in this review. One study reported outcomes associated with the full MetS symptom cluster. The included trials were small, short term, and at high risk of bias. All interventions lasted at least 6 weeks.

Hubungan Konsumsi Camilan dan Durasi Waktu Tidur dengan Obesitas di Permukiman Padat Kelurahan Simolawang, Surabaya

Background: Obesity in women with low socioeconomic status is easily found in slum area. Low socioeconomic status can have an impact on dietary changes, such as snacking that are known to be the cause of obesity. In addition to dietary changes, lifestyle changes such as sleep deprivation can also occur due to environmental conditions and job demands. Reduced bedtime will have an impact on health. Objectives: The purpose of this study was to analyze the association of sleep duration and snacking to obesity. Methods: This research was an observational analytical with cross sectional design. The sample was 70 married women aged 20-55 years in Simolawang, Simokerto Distict, Surabaya. Selection of smaple was using multistage random sampling. The data were collected by interview method with questionnaire to collect respondent characteristics data and sleep duration. Food Frequency Questionnaire (FFQ) was conducted to determine the snacking habits. Chi square test was used in the statistical analysis (a=0.05).Results: The data showed that  54.3% of respondents rarely consumed snack and 50% of them had sleep less time. The sleep duration had a significant association with obesity (p=0.009). In addition, snacking habits and obesity also showed a significant relationship (p=0.004).Conclusions: It is necessary to reduce the consumption of snacks and improve sleep time which is 7 hours per night to prevent obesity.ABSTRAK Latar Belakang: Obesitas pada wanita dengan status sosial ekonomi rendah banyak ditemui di permukiman padat. Rendahnya status sosial ekonomi dapat berdampak pada perubahan pola makan, seperti kebiasaan konsumsi camilan yang diketahui menjadi penyebab obesitas. Selain perubahan pola makan, perubahan gaya hidup seperti berkurangnya waktu tidur juga dapat terjadi karena kondisi lingkungan maupun tuntutan pekerjaan. Berkurangnya waktu tidur akan berdampak pada kesehatan.Tujuan: Untuk menganalisis hubungan kebiasaan konsumsi camilan dan durasi waktu tidur dengan obesitas pada ibu rumah tangga di permukiman padat penduduk. Metode: Penelitian ini merupakan penelitian observasional analitik dengan desain penelitian cross sectional. Sampel penelitian adalah 70 wanita yang sudah menikah berusia 20-55 tahun di Kelurahan Simolawang Kecamatan Simokerto, Surabaya. Pemilihan sampel dilakukan dengan menggunakan multistage random sampling. Pengambilan data dilakukan dengan metode wawancara menggunakan kuesioner untuk mendapatkan data karakteristik responden dan durasi waktu tidur. Food Frequency Questionnaire (FFQ) dilakukan untuk mengetahui kebiasaan konsumsi camilan. Analisis statistik dilakukan dengan menggunakan uji chi square (a=0,05).Hasil: Hasil menunjukkan bahwa 54,3% responden jarang mengonsumsi camilan dan 50% responden memiliki waktu tidur yang kurang. Durasi waktu tidur memiliki hubungan yang signifikan dengan kondisi obesitas (p=0,009). Selain itu kebiasaan konsumsi camilan dan obesitas juga menunjukkan adanya hubungan yang signifikan (p=0,004).Kesimpulan: Diperlukan adanya pembatasan konsumsi camilan dan tidur dengan durasi waktu cukup, yaitu 7 jam per malam untuk mencegah terjadinya obesitas.

Exploring the mediating role of energy balance-related behaviours in the association between sleep duration and obesity in European adults. The SPOTLIGHT project

Sleep restriction is a risk factor for weight gain and obesity. Few studies have formally investigated the mediating role of energy balance-related behaviours in the sleep - obesity association. The aim of this study was to explore the mediating role of physical activity, sedentary behaviours and dietary habits in the association of sleep duration with obesity in adults in five European urban regions. Data on self-reported sleep duration, energy balance-related behaviours, height and weight and other covariates were collected between February and September 2014 from participants to the SPOTLIGHT survey (N=5900, mean age 52years). Participants were recruited from 60 urban neighbourhoods in Belgium, France, Hungary, the Netherlands and the United Kingdom. Multilevel logistic regression analyses were used to assess the associations of sleep duration, energy balance-related behaviours and obesity and mediating effects were calculated using MacKinnon's product-of-coefficients method. Results indicated that a 1h increase in sleeping time was associated with a 14% lower likelihood of being obese (OR=0.86, 95%CI=0.80; 0.93). Only work-related sedentary behaviour was identified as a statistically significant mediator in the association between sleep duration and obesity for the total sample, and youngest and oldest age group. We did not find evidence for a mediating role of dietary habits and physical activities.

Behavioral interventions to promote adequate sleep among women: protocol for a systematic review and meta-analysis

BACKGROUND

Short and poor sleep have been associated with adverse health outcomes in adults, such as overweight/obesity and type 2 diabetes, especially among women. Women therefore represent an important target for interventions aimed at improving sleep and such interventions have been advocated to enhance maternal, fetal, and infant health. This systematic review will assess the efficacy or effectiveness of behavioral interventions aimed at promoting adequate sleep among women. The primary outcomes will be changes in sleep duration and/or sleep quality from baseline to post-intervention and to the last available follow-up measured either through self-reports or objectively. Secondary outcomes will be assessing the behavior change techniques that are responsible for the changes in sleep duration and quality among women.

METHODS

Behavioral interventions that are non-pharmacological and target either sleep directly or sleep hygiene behaviors will be included. Randomized controlled trials, quasi-experimental, and one-group pre-post studies will be included, but treated separately in the analyses, given that a limited number of studies on the topic of sleep is expected. MEDLINE/PubMed, PsycINFO, CINAHL, EMBASE, and Proquest Dissertations and Theses will be investigated. There will be no restriction on the year of publication of the articles, but we will include only the ones written in English or French. Two authors will independently assess articles for eligibility and will extract data using a standardized data extraction form that will have been previously pilot-tested. The quality of the studies will be assessed using the Effective Public Health Practice Project tool for quantitative study designs. The intervention procedures will be classified according to the latest validated taxonomy of behavior change techniques. If there is a sufficient number of studies (k > 5), a meta-analysis of the results will be performed with a random-effect model. If the heterogeneity is high (I ² ≥ 75%), it will be investigated through sensitivity analyses and meta-regression.

DISCUSSION

This review will provide valuable information to those interested in promoting adequate sleep among women and, hopefully, encourage additional research in this important field to promote maternal, fetal, and infant health.

SYSTEMATIC REVIEW REGISTRATION

The study protocol was registered in PROSPERO in October 2016 (CRD42016049538).

Sleep Duration and Obesity in Adults: What Are the Connections?

Collectively, cross-sectional and longitudinal studies on self-reported sleep duration and obesity do not show a clear pattern of association with some showing a negative linear relationship, some showing a U-shaped relationship, and some showing no relationship. Associations between sleep duration and obesity seem stronger in younger adults. Cross-sectional studies using objectively measured sleep duration (actigraphy or polysomnography (PSG)) also show this mixed pattern whereas all longitudinal studies to date using actigraphy or PSG have failed to show a relationship with obesity/weight gain. It is still too early and a too easy solution to suggest that changing the sleep duration will cure the obesity epidemic. Given novel results on emotional stress and poor sleep as mediating factors in the relationship between sleep duration and obesity, detection and management of these should become the target of future clinical efforts as well as future research.

Clinical Relevance of Sleep Duration: Results from a Cross-Sectional Analysis Using NHANES

STUDY OBJECTIVES

To assess the clinical relevance of sleep duration, hours slept were compared by health status, presence of insomnia, and presence of depression, and the association of sleep duration with BMI and cardiovascular risk was quantified.

METHODS

Cross-sectional analysis of subjects in the US National Health and Nutrition Examination Surveys using adjusted linear and logistic regressions.

RESULTS

A total of 22,281 adults were included, 37% slept ≤ 6 hours, 36% were obese, and 45% reported cardiovascular conditions. Mean sleep duration was 6.87 hours. Better health was associated with more hours of sleep. Subjects with poor health reported sleeping 46 min, (95% CI -56.85 to -35.67) less than subjects with excellent health. Individuals with depression (vs. not depressed) reported 40 min less sleep, (95% CI -47.14 to -32.85). Individuals with insomnia (vs. without insomnia) reported 39 min less sleep, (95% CI -56.24 to -22.45). Duration of sleep was inversely related to BMI; for every additional hour of sleep, there was a decrease of 0.18 kg/m(2) in BMI, (95% CI -0.30 to -0.06). The odds of reporting cardiovascular problems were 6.0% lower for every hour of sleep (odds ratio = 0.94, 95% CI [0.91 to 0.97]). Compared with subjects who slept ≤ 6 h, subjects who slept more had lower odds of reporting cardiovascular problems, with the exception of subjects ≥ 55 years old who slept ≥ 9 hours.

CONCLUSIONS

Long sleep duration is associated with better health. The fewer the hours of sleep, the greater the BMI and reported cardiovascular disease. A difference of 30 minutes of sleep is associated with substantive impact on clinical well-being.

The association between optimal lifestyle-related health behaviors and employee productivity

OBJECTIVE

To investigate the association between lifestyle-related health behaviors including sleep and the cluster of physical activity, no tobacco use, fruits and vegetables intake, and alcohol consumption termed the "Optimal Lifestyle Metric" (OLM), and employee productivity.

METHODS

Data were obtained from employee health assessments (N = 18,079). Regression techniques were used to study the association between OLM and employee productivity, sleep and employee productivity, and the interaction of both OLM and sleep on employee productivity.

RESULTS

Employees who slept less or more than 7 or 8 hours per night experienced significantly more productivity loss. Employees who adhered to all four OLM behaviors simultaneously experienced less productivity loss compared with those who did not.

CONCLUSIONS

Adequate sleep and adherence to the OLM cluster of behaviors are associated with significantly less productivity loss.

The impact of sleep duration on adolescent development: a genetically informed analysis of identical twin pairs

Recent work provides evidence that reduced sleep duration has detrimental effects on a range of developmentally related outcomes during adolescence. Yet, the potential confounding influence of genetic and shared environmental effects has not been sufficiently addressed. This study addresses this issue by analyzing cross-sectional data from the twin sub-sample of the first wave of the National Longitudinal Study of Adolescent Health [N ≈ 287 MZ (monozygotic) twin pairs; 50% male; 22% Black; mean age = 15.75]. Associations between sleep duration (measured through two different strategies, one tapping number of hours slept at night and the other measuring weeknight bedtimes) and seven outcomes (self-control, depressive symptoms, suicidal ideation, body mass index, violent delinquency, non-violent delinquency, and drug use) were estimated. Consistent with prior research, associations between sleep duration and several outcomes were statistically significant when using standard social science analytic methods. Yet, when employing a methodology that accounts for genetic and shared environmental influences, some of these associations were reduced to non-significance. Still, two consistent associations remained in that participants who reported sleeping fewer hours at night (or who reported later bedtimes) exhibited lower levels of self-control and more depressive symptoms. Implications of the findings and directions for future research are discussed.

Sleep quality and body mass index in college students: the role of sleep disturbances

OBJECTIVE

Obesity and its comorbidities have emerged as a leading public health concern. The aim of this study was to explore the relationship between body mass index (BMI) and sleep patterns, including duration and disturbances.

METHODS

A convenience sample of 515 college students completed an online survey consisting of the Pittsburgh Sleep Quality Index (PSQI), and self-reported height and weight to calculate BMI. Univariate and multivariate logistic regression analyses were performed using components of the PSQI as predictors of overweight (BMI ≥ 25).

RESULTS

One-third of the participants had BMI ≥ 25, and 51% were poor-quality sleepers (PSQI > 5). Controlling for age and sex, only sleep disturbances were associated with overweight (odds ratio = 1.66, 95% confidence interval [1.08, 2.57]).

CONCLUSIONS

Sleep disturbances, rather than sleep duration, predicted overweight among young adults; this is consistent with the most recent evidence in the literature. These findings support expanding the scope of wellness programs to promote healthy sleep among students.

Body mass index gain between ages 20 and 40 years and lifestyle characteristics of men at ages 40-60 years: the Adventist Health Study-2

BACKGROUND

Obesity increases risk of premature disease, and may be associated with unfavorable lifestyle changes that add to risk. This study analyzed the association of midlife BMI change with current lifestyle patterns among multiethnic men.

METHODS

Men aged 40-60 years (n=9864) retrospectively reported body weight between ages 20-40 years and current dietary, TV, physical activity and sleep practices in the Adventist Health Study II, a study of church-goers in the US and Canada. In multivariate logistic regression analysis, odds ratios for BMI gain were calculated for each lifestyle practice controlling for sociodemographic and other lifestyle factors and current BMI.

RESULTS

Men with median or higher BMI gain (2.79 kg/m(2)) between ages 20-40 years were more likely to consume a non-vegetarian diet, and engage in excessive TV watching and little physical activity and had a shorter sleep duration compared to men with BMI gain below the median (all p<0.001). In multivariate logistic analysis current BMI was significantly associated with all lifestyle factors (all p≤0.005). BMI gain was associated with lower odds of vegetarian diet (odds ratio [OR] 0.939; 95% confidence interval [CI] 0.921-0.957) and of physical activity ≥150 min/week (OR 0.979, 95% CI 0.960-0.999).

CONCLUSIONS

These findings imply that diet and less physical activity are associated with both gained and attained BMI, while inactivity (TV watching) and short sleep duration correlated only with attained BMI. Unhealthy lifestyle may add risk to that associated with BMI. Longitudinal and intervention studies are needed to infer causal relationships.

Sleep duration and all-cause mortality: a critical review of measurement and associations

PURPOSE

Variation in sleep duration has been linked with mortality risk. The purpose of this review is to provide an updated evaluation of the literature on sleep duration and mortality, including a critical examination of sleep duration measurement and an examination of correlates of self-reported sleep duration.

METHODS

We conducted a systematic search of studies reporting associations between sleep duration and all-cause mortality and extracted the sleep duration measure and the measure(s) of association.

RESULTS

We identified 42 prospective studies of sleep duration and mortality drawing on 35 distinct study populations worldwide. Unlike previous reviews, we find that the published literature does not support a consistent finding of an association between self-reported sleep duration and mortality. Most studies have employed survey measures of sleep duration, which are not highly correlated with estimates based on physiologic measures.

CONCLUSIONS

Despite a large body of literature, it is premature to conclude, as previous reviews have, that a robust, U-shaped association between sleep duration and mortality risk exists across populations. Careful attention must be paid to measurement, response bias, confounding, and reverse causation in the interpretation of associations between sleep duration and mortality.

The association between short sleep and obesity after controlling for demographic, lifestyle, work and health related factors

OBJECTIVE

The relationship between short sleep and obesity remains unclear, and a possible explanation is that many studies have not included sufficient control variables in the analyses. We examined the association between sleep and being overweight or obese after adjusting for the confounding contributions of 17 variables.

METHODS

A random sample of 1162 Australian adults from three regional cities in central Queensland, Australia, participated in a telephone survey. A series of increasingly complex multinomial logistic regression models were employed to assess the association between short sleep (< or = 6 h) being overweight (body mass index [BMI] 25-29.99 kg/m2) and obesity (BMI, > or = 30 kg/m2), while controlling for several demographic, lifestyle, work, and health-related variables.

RESULTS

The results suggested obesity was significantly associated with short sleep, age, male gender, lower education level, less physical activity, more sitting time, working longer hours, drinking more alcohol, having diabetes mellitus (DM), and having hypertension. Being overweight was significantly associated with age, male gender, smoking, and working more than 43hours per week.

CONCLUSIONS

After adjustment of several confounding variables, a significant association between short sleep and obesity was obtained, but there was no association between short sleep and being overweight. Additional studies applying comprehensive analytic models and stronger research designs are needed to confirm our findings.

The role of sleep duration in the regulation of energy balance: effects on energy intakes and expenditure

Short sleep duration and obesity are common occurrence in today's society. An extensive literature from cross-sectional and longitudinal epidemiological studies shows a relationship between short sleep and prevalence of obesity and weight gain. However, causality cannot be inferred from such studies. Clinical intervention studies have examined whether reducing sleep in normal sleepers, typically sleeping 7-9 h/night, can affect energy intake, energy expenditure, and endocrine regulators of energy balance. The aim of this review is to evaluate studies that have assessed food intake, energy expenditure, and leptin and ghrelin levels after periods of restricted and normal sleep. Most studies support the notion that restricting sleep increases food intake, but the effects on energy expenditure are mixed. Differences in methodology and component of energy expenditure analyzed may account for the discrepancies. Studies examining the effects of sleep on leptin and ghrelin have provided conflicting results with increased, reduced, or unchanged leptin and ghrelin levels after restricted sleep compared to normal sleep. Energy balance of study participants and potential sex differences may account for the varied results. Studies should strive for constant energy balance and feeding schedules when assessing the role of sleep on hormonal profile. Although studies suggest that restricting sleep may lead to weight gain via increased food intake, research is needed to examine the impact on energy expenditure and endocrine controls. Also, studies have been of short duration, and there is little knowledge on the reverse question: does increasing sleep duration in short sleepers lead to negative energy balance?

Perceived racial discrimination as an independent predictor of sleep disturbance and daytime fatigue

Perceived discrimination is a potential cause of racial and ethnic disparities in health. Disturbed sleep may serve as a mechanism linking perceived racism with health consequences. This study investigates data from 7,148 adults from Michigan and Wisconsin who participated in the 2006 Behavioral Risk Factor Surveillance System. Hierarchical logistic regression analyses explored associations between perceived racial discrimination and self-reported sleep disturbance and daytime fatigue. Sleep disturbance and daytime fatigue were reported in 19% and 21% of the sample, respectively. Black/African American respondents (21%) report perceiving worse experiences, compared to people of other races, when seeking health care at higher rates than non-Hispanic White respondents (3%). Results from logistic regression models show that perceived racial discrimination is associated with increased risks of sleep disturbance (odds ratio [OR] = 2.62, p < .0001) and daytime fatigue (OR = 2.07, p < .0001). After adjustment for all covariates, perceived discrimination remains a significant predictor of sleep disturbance (OR = 1.60, p = .04). The interaction between perceived racism and race (Black/African American vs. non-Hispanic White) was nonsignificant. This population-based research adds to the growing body of data, suggesting that perceived racism may impact health via its influence on sleep-wake behaviors.

The effect of work shift and sleep duration on various aspects of police officers' health

Police officers are prone to cardiovascular disease, overweight, and obesity. Because night-shift work affects sleep, a modifiable risk factor linked to chronic disease, the researchers explored the relationship among shift work, sleep, and wellness for police officers. Sleep, C-reactive protein (CRP) levels, stress, fatigue, and body mass index were used to compare officers who worked primarily day shifts to those who worked primarily evening or night shifts, and officers who slept less than 6 hours per day to those who slept at least 6 hours per day. A cross-sectional study of 85 male officers, 20 to 63 years old, was completed at three Midwestern police departments. The Pittsburgh Sleep Quality Index was used to assess sleep. A questionnaire was used to collect officer demographics and work hours. Other measurements included serum CRP, height, weight, perceived stress, and vital exhaustion. The relative risk of sleeping less than 6 hours per day for officers who primarily worked non-day shifts, compared to those who worked day shifts, was 14.27 (95% confidence interval [CI], 1.98-102.95, p < .001), and the relative risk of overall poor sleep quality for officers who slept less than 6 hours per day, compared to those who slept more hours, was 2.44 (95% CI, 1.15-5.20, p = .027). CRP was not associated with shift or sleep duration, even when adjusted for officers' ages.

Interaction between physical activity and sleep duration in relation to insulin resistance among non-diabetic Chinese adults

BACKGROUND

It is of a public health interest to explore the relationship between different types of physical activity, sleep duration and diabetes/insulin resistance. However, little is known about such relationship. This study examines the single and joint associations of different types of physical activity, and sleep duration on insulin resistance among non-diabetic Chinese adults.

METHODS

Data was collected from 1124 non-diabetic adults in Jiangsu Province from the China Health and Nutrition Survey (CHNS). Domestic, occupational, transportation and leisure physical activity were assessed in terms of metabolic equivalent (MET)-hours-per-week to account for both intensity and time spent. Sleep duration was categorized into three groups: ≤ 7 hours, 7-9 hours, and ≥ 9 hours. Insulin resistance was evaluated by the homeostasis model of assessment (HOMA) and defined as the highest quartile of HOMA.

RESULTS

Total physical activity was mainly composed of occupational activity (75.1%), followed orderly by domestic, transportation and leisure time activity in both men and women. Total physical activity level was strongly negatively associated with fasting insulin and HOMA (p < 0.001). Among four types of physical activity, occupational activity was significantly negatively associated with HOMA after full adjustment (p < 0.05). Transportation activity was also negatively associated with HOMA when adjusted for age and gender (p = 0.028). Moreover, the combination of low physical activity and short sleep duration was associated with the highest odds of insulin resistance (adjusted OR = 3.26, 95% CI: 1.57-6.78), compared to those with high physical activity and adequate sleep duration.

CONCLUSIONS

Physical activity, mainly occupational physical activity, was negatively associated with insulin resistance in non-diabetic Chinese population, independently of potential confounders. There was a synergic effect of low physical activity and short sleep duration on insulin resistance.

State and regional prevalence of sleep disturbance and daytime fatigue

STUDY OBJECTIVES

Social and demographic influences are important for sleep attainment. Geographic location has not been previously explored.

METHODS

Data from the 2006 Behavioral Risk Factor Surveillance System (BRFSS) were used (N = 157,319). Participants answered a question on Sleep Disturbance and Daytime Fatigue. Thirty-six states/regions provided data on these items. Prevalence estimates were adjusted for age, sex, ethnoracial group, education, income, employment, general health, healthcare access, and depression. Chi-squared tests were conducted across states and census regions, and pseudo-R(2) values were computed for the effect of state, relative to other predictors. To evaluate potential mediators of census region differences, an analysis of p value change associated with specific covariates and covariate groups was undertaken.

RESULTS

Adjusted prevalence rates of Sleep Disturbance differed across states/regions overall (χ(2) = 412.3, p < 0.0001), as well as separately for men (χ(2) = 139.5, p < 0.0001) and women (χ(2) = 350.0, p < 0.0001), as did rates of Daytime Fatigue overall (χ(2) = 245.7, p < 0.0001), and separately for men (χ(2) = 117.5, p < 0.0001) and women (χ(2) = 181.2, p < 0.0001). Analysis of pseudo-R(2) values revealed that despite these significant findings, state differences were an overall weak predictor, representing 1.30% to 1.73% of the magnitude of the effect of the best predictor (mental health). When Census regions were compared, significant differences were found for Sleep Disturbance (p = 0.002), but after adjustment for covariates, these were no longer significant. Differences existed for Daytime Fatigue in adjusted analyses overall (p < 0.0001), with the West reporting the fewest complaints and the South reporting the most.

CONCLUSIONS

These results demonstrate that reports of sleep related complaints vary across states, independent (at least partially) of factors that influence circadian rhythms (e.g., latitude).

Time use choices and healthy body weight: a multivariate analysis of data from the American Time Use Survey

BACKGROUND

We examine the relationship between time use choices and healthy body weight as measured by survey respondents' body mass index (BMI). Using data from the 2006 and 2007 American Time Use Surveys, we expand upon earlier research by including more detailed measures of time spent eating as well as measures of physical activity time and sedentary time. We also estimate three alternative models that relate time use to BMI.

RESULTS

Our results suggest that time use and BMI are simultaneously determined. The preferred empirical model reveals evidence of an inverse relationship between time spent eating and BMI for women and men. In contrast, time spent drinking beverages while simultaneously doing other things and time spent watching television/videos are positively linked to BMI. For women only, time spent in food preparation and clean-up is inversely related to BMI while for men only, time spent sleeping is inversely related to BMI. Models that include grocery prices, opportunity costs of time, and nonwage income reveal that as these economic variables increase, BMI declines.

CONCLUSIONS

In this large, nationally representative data set, our analyses that correct for time use endogeneity reveal that the Americans' time use decisions have implications for their BMI. The analyses suggest that both eating time and context (i.e., while doing other tasks simultaneously) matters as does time spent in food preparation, and time spent in sedentary activities. Reduced form models suggest that shifts in grocery prices, opportunity costs of time, and nonwage income may be contributing to alterations in time use patterns and food choices that have implications for BMI.

Sleep difficulties and obesity among preadolescents

OBJECTIVE

To determine if sleep difficulties are associated with overweight/obesity status among preadolescents.

METHODS

A total of 606 (288 males, 318 females) students, ages 11-13 years from southern Ontario, Canada, were included in this analysis. Overweight/obesity status was determined using age- and gender-specific criteria. Sleep difficulty status was determined if the parents reported children 'sometimes' or 'often' experiencing waking up at night, snoring or breathing loudly, and restlessness while sleeping. Logistic regression analysis was used to examine the association of childhood overweight status and sleep difficulties adjusting for age, gender, total physical activity score, total calories intake, maternal education level, and total hours of sleep.

RESULTS

In this sample, 28% of children (76 boys and 95 girls) were identified as being overweight or obese. Relative to their normal-weight peers, overweight and obese individuals reported a higher prevalence of sleep difficulties (10.3% vs. 26.3%, p < 0.0001), reduced hours of sleep (9.4 vs. 9.2 hrs, p < 0.001), and a lower physical activity score (17.2 vs. 19.1, p < 0.01). Using a multiple logistic regression model, in comparison to children reporting none of the three sleep behaviour problems, the odds ratios (95% CI) of being overweight or obese for those having any one, two, or all three sleep behaviour problems were 1.04 (0.46-2.36), 1.35 (0.58-2.10), and 3.52 (1.42-8.74), respectively.

CONCLUSIONS

The results suggest that the risk of overweight/obesity is associated with sleep difficulties among preadolescents. Further study is needed to determine the direction of this relationship.

Sleep and obesity

PURPOSE OF REVIEW

This review summarizes the most recent evidence linking decreased sleep duration and poor sleep quality to obesity, focusing upon studies in adults.

RECENT FINDINGS

Published and unpublished health examination surveys and epidemiological studies suggest that the worldwide prevalence of obesity has doubled since 1980. In 2008, 1 in 10 adults was obese, with women more likely to be obese than men. This obesity epidemic has been paralleled by a trend of reduced sleep duration. Poor sleep quality, which leads to overall sleep loss has also become a frequent complaint. Growing evidence from both laboratory and epidemiological studies points to short sleep duration and poor sleep quality as new risk factors for the development of obesity.

SUMMARY

Sleep is an important modulator of neuroendocrine function and glucose metabolism and sleep loss has been shown to result in metabolic and endocrine alterations, including decreased glucose tolerance, decreased insulin sensitivity, increased evening concentrations of cortisol, increased levels of ghrelin, decreased levels of leptin, and increased hunger and appetite. Recent epidemiological and laboratory evidence confirm previous findings of an association between sleep loss and increased risk of obesity.

Relationship between body mass index and perceived insufficient sleep among U.S. adults: an analysis of 2008 BRFSS data

Background

Over the past 50 years, the average sleep duration for adults in the United States has decreased while the prevalence of obesity and associated outcomes has increased. The objective of this study was to determine whether perceived insufficient sleep was associated with body mass index (BMI) in a national sample.

Methods

We analyzed data from the 2008 Behavioral Risk Factor Surveillance System (BRFSS) survey (N = 384,541) in which respondents were asked, "During the past 30 days, for about how many days have you felt you did not get enough rest or sleep?" We divided respondents into six BMI categories and used multivariable linear regression and logistic regression analyses to assess the association between BMI categories and days of insufficient sleep after adjusting for sociodemographic variables, smoking, physical activity, and frequent mental distress.

Results

Adjusted mean days of insufficient sleep ranged from 7.9 (95% confidence interval [CI]: 7.8, 8.0) days for people of normal weight to 10.5 (95% CI: 10.2, 10.9) days for those in the highest weight category (BMI ≥ 40). Days of perceived insufficient sleep followed a linear trend across BMI categories. The likelihood of reporting ≥14 days of insufficient sleep in the previous 30 days was higher for respondents in the highest weight category than for those who were normal weight (34.9% vs. 25.2%; adjusted odds ratio = 1.7 (95% CI: 1.5, 1.8]).

Conclusion

Among U.S. adults, days of insufficient rest or sleep strongly correlated with BMI. Sleep sufficiency should be an important consideration in the assessment of the health of overweight and obese people and should be considered by developers of weight-reduction programs.

Obesity and short sleep: unlikely bedfellows?

The link between habitual short sleep and obesity is critically examined from a sleep perspective. Sleep estimates are confounded by 'time in bed', naps; the normal distribution of sleep duration. Wide categorizations of 'short sleep', with claims that <7 h sleep is associated with obesity and morbidity, stem from generalizations from 5 h sleepers (<8% of adults) and acute restriction studies involving unendurable sleepiness. Statistically significant epidemiological findings are of questionable clinical concern, even for 5 h sleepers, as any weight gains accumulate slowly over years; easily redressed by e.g. short exercise exposures, contrasting with huge accumulations of 'lost' sleep. Little evidence supports 'more sleep', alone, as an effective treatment for obesity. Impaired sleep quality and quantity are surrogates for many physical and psychological disorders, as can be obesity. Advocating more sleep, in these respects, could invoke unwarranted use of sleep aids including hypnotics. Inadequate sleep in obese children is usually symptomatic of problems not overcome by increasing sleep alone. Interestingly, neuropeptides regulating interactions between sleep, locomotion and energy balance in normal weight individuals, are an avenue for investigation in some obese short sleepers. The real danger of inadequate sleep lies with excessive daytime sleepiness, not obesity.

The end of sleep: 'sleep debt' versus biological adaptation of human sleep to waking needs

It is argued that the latter part of usual human sleep is phenotypically adaptable (without 'sleep debt') to habitual shortening or lengthening, according to environmental influences of light, safety, food availability and socio-economic factors, but without increasing daytime sleepiness. Pluripotent brain mechanisms linking sleep, hunger, foraging, locomotion and alertness, facilitate this time management, with REM acting as a 'buffer' between wakefulness and nonREM ('true') sleep. The adaptive sleep range is approximately 6-9h, although, a timely short (<20 min) nap can equate to 1h 'extra' nighttime sleep. Appraisal of recent epidemiological findings linking habitual sleep duration to mortality and morbidity points to nominal causal effects of sleep within this range. Statistical significance, here, may not equate to real clinical significance. Sleep durations outside 6-9h are usually surrogates of common underlying causes, with sleep associations taking years to develop. Manipulation of sleep, alone, is unlikely to overcome these health effects, and there are effective, rapid, non-sleep, behavioural countermeasures. Sleep can be taken for pleasure, with minimal sleepiness; such 'sleepability' is 'unmasked' by sleep-conducive situations. Sleep is not the only anodyne to sleepiness, but so is wakefulness, inasmuch that some sleepiness disappears when wakefulness becomes more challenging and eventful. A more ecological approach to sleep and sleepiness is advocated.