Short Sleep Duration and Dietary Intake: Epidemiologic Evidence,Mechanisms, and Health Implications

Links between short sleep duration and obesity, type 2 diabetes, hypertension, and cardiovascular disease may be mediated through changes in dietary intake. This review provides an overview of recent epidemiologic studies on the relations between habitual short sleep duration and dietary intake in adults from 16 cross-sectional studies. The studies have observed consistent associations between short sleep duration and higher total energy intake and higher total fat intake, and limited evidence for lower fruit intake, and lower quality diets. Evidence also suggests that short sleepers may have irregular eating behavior deviating from the traditional 3 meals/d to fewer main meals and more frequent, smaller, energy-dense, and highly palatable snacks at night. Although the impact of short sleep duration on dietary intake tends to be small, if chronic, it may contribute to an increased risk of obesity and related chronic disease. Mechanisms mediating the associations between sleep duration and dietary intake are likely to be multifactorial and include differences in the appetite-related hormones leptin and ghrelin, hedonic pathways, extended hours for intake, and altered time of intake. Taking into account these epidemiologic relations and the evidence for causal relations between sleep loss and metabolism and cardiovascular function, health promotion strategies should emphasize improved sleep as an additional factor in health and weight management. Moreover, future sleep interventions in controlled studies and sleep extension trials in chronic short sleepers are imperative for establishing whether there is a causal relation between short sleep duration and changes in dietary intake.     

The Effect of Sleep Duration on the Risk of Unintentional Injury in Korean Adults

Objectives

The decrease or increase in sleep duration has recently been recognized as a risk factor for several diseases, including hypertension and obesity. Many studies have explored the relationship of decreased sleep durations and injuries, but few have examined the relationship between increased sleep duration and injury. The objective of this research is to identify the risk for injury associated with both decreased and increased sleep durations.

Methods

Data from the 2010 Community Health Survey were used in this study. We conducted logistic regression with average sleep duration as the independent variable, injury as a dependent variable, and controlling for age, sex, occupation, education, region (cities and provinces), smoking, alcohol use, body mass index, hypertension, diabetes, arthritis, and depression. Seven categories of sleep duration were established: ≤4, 5, 6, 7, 8, 9, and ≥10 hours.

Results

Using 7 hours of sleep as the reference, the adjusted injury risk (odds ratio) for those sleeping a total of ≤4 h/d was 1.53; 1.28 for 5 hours, for 1.11 for 6 hours, 0.98 for 8 hours, 1.12 for 9 hours, and 1.48 for ≥10 hours. The difference in risk was statistically significant for each category except for the 8 and 9 hours. In this study, risk increased as the sleep duration decreased or increased, except for the 8 and 9 hours.

Conclusions

This research found that either a decrease or increase in sleep duration was associated with an increased risk for injury. The concept of proper sleep duration can be evaluated by its associated injury risk.     

北京市海淀区居民睡眠时间与糖尿病患病的相关性研究

目的 分析北京市海淀区18～79岁成年人睡眠时间与糖尿病患病之间的相关性。 方法 数据来源于2019年北京市海淀区成人慢性病及其危险因素监测,采用logistic回归分析睡眠时间和糖尿病的关联,采用限制性立方样条法分析睡眠时间和糖尿病患病风险的剂量-反应关系。 结果 调查人群糖尿病患病率为15.6%,平均睡眠时间为（7.24±1.15）h。经过多因素调整后,与睡眠时间7～9 h相比,睡眠时间≤7 h者的糖尿病患病风险增加56%（OR = 1.56,95%CI: 1.31～1.86）,而睡眠时间≥9 h者的糖尿病患病风险并未明显增加（OR = 1.13,95%CI: 0.78～1.60)。限制性立方样条法结果显示,睡眠时间与糖尿病患病的关联强度呈“U”型分布（非线性检验χ2 = 31.259,P＜0.001）,睡眠时间约为7h时,糖尿病患病风险最低。 结论 北京市海淀区成年人睡眠时间过短可能会增加糖尿病患病风险。     

The Role of Cognitive Impairment,Physical Disability,and Chronic Conditions in the Association of Sleep Duration With All-Cause Mortality Among Very Old Adults

ObjectiveThis study aimed to examine the relationship between sleep duration and all-cause mortality, and to assess the role of cognitive impairment, physical disability, and chronic conditions on this association among very old adults.DesignA prospective cohort study.Setting and ParticipantsWithin the Chinese Longitudinal Healthy Longevity Surveys, 17,637 oldest-old aged 80-105 years were followed up to 10 years (2005- 2014).MeasuresData on sleep duration at baseline were based on self-report and were categorized as short (<7 hour), moderate (7-9 hours), and long sleep (>9 hours). Information on cognitive function using the Mini-Mental State Examination (MMSE), physical disability using Activities of Daily Living (ADL), and chronic conditions including diabetes, heart disease, stroke, asthma, and cancer were collected at baseline based on a structured questionnaire. Information about vital status was ascertained and confirmed by a close family member or village doctor of the participant during the follow-up. Data were analyzed using Cox proportional hazards models, with adjustment for potential confounders.ResultsDuring the follow-up of 10 years, 11,067 (62.7%) participants died. The multivariate-adjusted hazard ratios (HRs) with 95% confidence interval (CI) for mortality were 1.03 (0.98-1.09) for short sleep and 1.13 (1.08-1.18) for long sleep compared with moderate sleep duration. In stratified analysis by cognitive impairment, physical disability, and chronic conditions, the risk of morality was present only among people with MMSE scores ≤24 but did not differ much when stratified by physical disability and chronic conditions. There was a statistically significant interaction between long sleep and cognitive impairment on mortality (P for interaction = .002).Conclusions and ImplicationsLong sleep duration is associated with higher risk of mortality in very old adults independently of health conditions. Cognitive impairment may enhance this association. These findings suggest that health practitioners and families should be aware of the potential adverse prognosis associated with long sleep.     

A Prospective Cohort Study on the Relationship of Sleep Duration With All-cause and Disease-specific Mortality in the Korean Multi-center Cancer Cohort Study

Objectives

Emerging evidence indicates that sleep duration is associated with health outcomes. However, the relationship of sleep duration with long-term health is unclear. This study was designed to determine the relationship of sleep duration with mortality as a parameter for long-term health in a large prospective cohort study in Korea.

Methods

The study population included 13 164 participants aged over 20 years from the Korean Multi-center Cancer Cohort study. Information on sleep duration was obtained through a structured questionnaire interview. The hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality were estimated using a Cox regression model. The non-linear relationship between sleep duration and mortality was examined non-parametrically using restricted cubic splines.

Results

The HRs for all-cause mortality showed a U-shape, with the lowest point at sleep duration of 7 to 8 hours. There was an increased risk of death among persons with sleep duration of ≤5 hours (HR, 1.21; 95% CI, 1.03 to 1.41) and of ≥10 hours (HR, 1.36; 95% CI, 1.07 to 1.72). In stratified analysis, this relationship of HR was seen in women and in participants aged ≥60 years. Risk of cardiovascular disease-specific mortality was associated with a sleep duration of ≤5 hours (HR, 1.40; 95% CI, 1.02 to 1.93). Risk of death from respiratory disease was associated with sleep duration at both extremes (≤5 and ≥10 hours).

Conclusions

Sleep durations of 7 to 8 hours may be recommended to the public for a general healthy lifestyle in Korea.     

Short sleep duration as a risk factor for the development of the metabolic syndrome in adults

Objective

The objective of this study was to investigate the association between self-reported sleep duration and the incidence of features of the metabolic syndrome in adults.

Methods

A longitudinal analysis from the Quebec Family Study (Canada) was conducted on 293 participants, aged 18 to 65 years, followed for a mean of 6 years (until 2001). Participants were categorized as short (≤ 6 h), adequate (7–8 h) or long (≥ 9 h) sleepers. The metabolic syndrome was defined according to the American Heart Association/National Heart, Lung, and Blood Institute's criteria. The hypertriglyceridemic waist phenotype was defined as high waist circumference (≥ 90 cm in men and ≥ 85 cm in women) combined with high fasting triglyceride level (≥ 2.0 mmol/L in men and ≥ 1.5 mmol/L in women).

Results

The incidence rates of metabolic syndrome and hypertriglyceridemic waist phenotype were 9.9% and 7.5%, respectively. Short sleepers were significantly more at risk of developing the metabolic syndrome (relative risk (RR): 1.74; 95% confidence interval (CI): 1.05–2.72) and the hypertriglyceridemic waist phenotype (RR: 1.82; 95% CI: 1.16–2.79), compared to those sleeping 7 to 8 h per night after adjusting for covariates. However, long sleep duration was not associated with an increased risk of developing the metabolic syndrome or the hypertriglyceridemic waist phenotype (either unadjusted or adjusted models).

Conclusion

Short sleep duration is associated with an increased risk of developing features of the metabolic syndrome in adults.     

Sleep duration and obesity in adulthood: An updated systematic review and meta-analysis

Short and long sleep duration have been associated with risk of obesity in children and adolescents. Evidence in adults is more mixed, with biological and psychosocial factors underlying these relationships mostly unknown. This review aimed at qualitatively and quantitatively summarizing previous studies on sleep duration as a predictor of obesity in adults in order to provide an update of the state of art in this field and clarify these relationships. Odds ratios at 95% Confidence Intervals (CI) were estimated using random-effects models. Heterogeneity of effects distribution and publication bias were tested. Twelve articles were selected for short sleep (n = 154,936) and eight for long sleep duration (n = 152,192). Results indicated that short sleep duration (OR: 1.412; 95% CI: 1.177–1.694) was significantly associated with the risk of future obesity, and that long sleep duration (OR: 0.995; 95% CI: 0.889–1.114) was not associated. Heterogeneity was high and lowered to non-significant values when considering gender and extremes of short/long sleep duration. Results seem to confirm a potential role of short sleep duration in predicting but results on long sleep are still mixed. Future investigations on potential mediators of such relationships are needed.     

Associations of Diet Quality and Sleep Quality with Obesity

Short sleep duration or poor sleep quality has been associated with an increased risk of obesity. Although the underlying mechanism remains unclear, one proposed pathway is poor diet quality. This cross-sectional study investigated whether diet quality modifies the association between sleep status and obesity in Korean adults. We used the baseline data and samples of 737 men and 428 women (n = 1165) aged 19–64, who participated in the prospective Ewha–Boramae cohort study. Sleep duration was dichotomized into ≥7 h (adequate) and <7 h (insufficient). Pittsburgh Sleep Quality Index (PSQI) values, reflecting sleep quality, were dichotomized into >5 (poor quality) and ≤5 (good quality). Diet quality was evaluated by the Recommended Food Score (RFS). Obesity was associated with higher rates of insufficient sleep and poor sleep quality in women, but not in men. After adjustment for covariates, women with poor sleep quality had a higher risk of obesity than women with good sleep quality (OR = 2.198; 95% CI = 1.027–4.704); this association occurred only in the group with RFS ≤ median score. Our findings support a significant association between sleep quality and obesity, and this association has been potentially modified by dietary quality in women.     

Self-reported short sleep duration among US adults by disability status and functional disability type: Results from the 2016 Behavioral Risk Factor Surveillance System

BackgroundShort sleep duration is associated with an increased risk of chronic disease and all-cause death. A better understanding of sleep disparities between people with and without disabilities can help inform interventions designed to improve sleep duration among people with disabilities.ObjectiveTo examine population-based prevalence estimates of short sleep duration by disability status and disability type among noninstitutionalized adults aged ≥18 years.MethodsData from the 2016 Behavioral Risk Factor Surveillance System were used to assess prevalence of short sleep duration among adults without and with disabilities (serious difficulty with cognition, hearing, mobility, or vision; any difficulty with self-care or independent living). Short sleep duration was defined as <7 h per 24-h period. We used log-binomial regression to estimate prevalence ratios (PRs) and 95% confidence intervals (CIs) while adjusting for socioeconomic and health-related characteristics.ResultsAdults with any disability had a higher prevalence of short sleep duration than those without disability (43.8% vs. 31.6%; p < .001). After controlling for selected covariates, short sleep was most prevalent among adults with multiple disabilities (PR 1.40, 95% CI: 1.36–1.43), followed by adults with a single disability type (range: PR 1.13, 95% CI: 1.03–1.24 [for independent living disability] to PR 1.25, 95% CI: 1.21–1.30 [for mobility disability]) compared to adults without disability.ConclusionsPeople with disabilities had a higher likelihood of reporting short sleep duration than those without disabilities. Assessment of sleep duration may be an important component in the provision of medical care to people with disabilities.     

The association of sleep duration and sleep quality with non-alcoholic fatty liver disease in a Taiwanese population

ObjectiveThe association of sleep duration/quality with nonalcoholic fatty liver disease (NAFLD) is inconclusive. Several important covariates were not adjusted concomitantly in some studies, and the severity of NAFLD was not considered. Furthermore, the gender impact of sleep duration or sleep quality on NAFLD remains unclear. We thus aimed to examine the association of sleep duration and quality with NAFLD by gender in a Taiwanese population.MethodsA total of 6663 subjects aged 18 years or more were enrolled. The severity of NAFLD was divided into mild, moderate, and severe degrees based on ultrasound findings. The sleep duration was classified into three groups: short (<6 h), normal (6–8 h), and long (>8 h). Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality, and poor sleep quality was defined as a global PSQI score greater than 5.ResultsAfter adjustment for potential confounders, multinomial logistic regression showed that poor sleep quality was negatively associated with both mild and moderate-to-severe NAFLD in males, but sleep duration was not independently related to NAFLD. In females, sleep condition was not related to NAFLD.ConclusionsPoor sleep quality but not sleep duration was associated with a lower risk of not only moderate to severe but also mild NAFLD in males. In females, the association of sleep quality and duration with the risk of NAFLD was insignificant.