The prospective association between sleep duration and the development of late-life depressive symptomology is unclear.

To investigate sleep duration from midlife to late life in relation to risk of depressive symptoms in late life.

A total of 14 361 participants from the Singapore Chinese Health Study were included in the present study. Daily sleep duration was self-reported at baseline (mean age of 52.4 years; 1993–98), follow-up 2 (mean age of 65.2 years; 2006–10) and follow-up 3 (mean age of 72.5 years; 2014–16) interviews. Depressive symptoms were evaluated using the Geriatric Depression Scale at follow-up 3 interviews. Modified Poisson regression models were performed to estimate relative risks and 95% confidence intervals of late-life depressive symptoms in relation to sleep duration at baseline and the two follow-up interviews.

Compared with sleeping 7 h per day, a short sleep duration of ≤5 h per day at baseline (i.e. midlife) was related to a higher risk of depressive symptoms (relative risk 1.10, 95% CI 1.06–1.15), and this risk was not affected by subsequent prolongation of sleep. Conversely, a long sleep duration of ≥9 h per day at baseline was not related to risk of depressive symptoms. At follow-up 3 (i.e. late life), both short sleep (relative risk 1.20, 95% CI 1.16–1.25) and long sleep (relative risk 1.12, 95% CI 1.07–1.18) duration were cross-sectionally associated with depressive symptoms.

Short sleep duration in midlife, regardless of subsequent prolongation, is associated with an increased risk of depression in late life. Contrariwise, both short and long sleep duration in late life co-occur with depressive symptoms.

A growing number of Korean adolescents consume energy drinks, which may increase the risk of obesity, anxiety and insomnia. We examined whether poor sleep was associated with energy drink consumption among study participants.

We used a cross-sectional design.

The Korea Youth Risk Behavior Web-Based Survey data from 2019.

To determine the association between sleep and energy drink consumption, we compared the independent variables for 50,455 adolescents in Korea (aged 14–19 years) using multivariate logistic regression and sensitivity analyses.

In Korea, 69·5 % adolescents consumed energy drinks, 17·1 % slept for less than 5 h, 22·4 % slept for 5–6 h, 23·8 % slept for 6–7 h, 19·9 % slept for 7–8 h and 16·7 % slept for 8 h or more. Regarding sleep satisfaction, 21·0 % reported sufficient, 32·6 % reported just enough and 46·5 % reported insufficient. Regarding sleep duration, it was found that less than 5 h (OR, 2·36; 95 % CI (2·14, 2·60)) and lower sleep satisfaction (OR, 1·12; 95 % CI (1·03, 1·21)) were highly associated with energy drink consumption, with statistical significance at P < 0·05. Adolescents with lower sleep duration (adjusted OR (aOR), 6·37; 95 % CI (4·72, 8·61)) and a lack of sleep satisfaction (aOR, 1·44; 95 % CI (1·16, 1·78)) reported drinking a high amount of energy drinks, that is, at least once a day.

In addition to efforts to decrease the amount of energy drinks consumed, sleep hygiene education needs to be strengthened.

We investigated the association between dietary oxidative balance score (DOBS) and mortality and whether this association can be modified by sleep duration.

We calculated DOBS to estimate the overall oxidative effects of the diet, with higher DOBS reflecting more antioxidant intake and less pro-oxidant intake. Cox proportional hazards models were employed to examine the associations between DOBS and all-cause, CVD and cancer mortality in the general population and people with different sleep durations.

Prospective analysis was conducted using data from the US National Health and Nutrition Examination Survey (NHANES, 2005–2015).

A total of 15 991 US adults with complete information on dietary intake, sleep duration and mortality were included.

During a median follow-up of 7·4 years, 1675 deaths were observed. Participants in the highest quartile of DOBS were significantly associated with the lower risk of all-cause mortality (hazard ratio (HR) = 0·75; 95 % CI 0·61, 0·93) compared with those in the lowest. Furthermore, we found statistically significant interactions between DOBS and sleep duration on all-cause mortality (P interaction = 0·021). The inverse association between DOBS and all-cause mortality was significant in short sleepers (HR = 0·66, 95 % CI 0·48, 0·92), but not in normal and long sleepers.

Our study observed that higher DOBS was associated with lower all-cause mortality, and this association appeared to be stronger among short sleepers. This study provides nutritional guidelines for improving health outcomes in adults, especially for short sleepers.

It has been well known that air pollution and sleep deprivation individually have impacts on human health; however, the association between the two has not been well researched. The aim of this study was to investigate this relationship at a community level.

We collected sleep outcomes from the Korean Community Health Survey between years of 2008 and 2016. The data contained 1 130 080 selected adults aged ⩾ 19 years, from 141 communities. As sleep outcomes, annual chronic sleep deprivation (% of people who sleep ⩽ 5 h per day on average) and average values of daily mean sleep duration were used. Community-specific annual averages of particulate matter with a diameter ⩽ 10 μm (PM10), nitrogen dioxide (NO2) and carbon monoxide (CO) were collected and then applied to a linear mixed effects model to estimate the association between air pollution over the past 4 years and sleep outcomes. Population density, green space, health behaviour, and gross regional domestic product per capita variables were considered as confounders in all mixed effect models.

From the linear mixed effect models, we found that the chronic sleep deprivation % was positively associated with PM10 (0.33% increase with 95% CI 0.05–0.60; per 10 μg/m3) and NO2 (0.68% with 95% CI 0.44–0.92; per 10 ppm). Higher PM10 and NO2 were also associated with shorter sleep duration, with a reduction of 0.37 min (95% CI −0.33 to 1.07 min; per 10 μg/m3) and 2.09 min (95% CI 1.50–2.68 min; per 10 ppm), respectively. The associations between PM10 and sleep outcomes were higher in females than males and in the older age groups (⩾ 60-years) than in younger age groups (19–39 and 40–59 years). However, the association between NO2 and sleep outcomes were more higher in males than in females and in the younger age groups (19–39 years) than other age groups.

Our findings provide epidemiological evidence that long-term interventions to reduce air pollutions are anticipated to provide improvements in sleep deficiency.

To examine the association between sleep duration in different stages of life and amnestic mild cognitive impairment (aMCI).

A total of 2472 healthy elderly and 505 patients with aMCI in China were included in this study. The study analyzed the association between aMCI and sleep duration in different stages of life.

We compared sleep duration in different stages of life and analyzed the association between Montreal Cognitive Assessment scores and sleep duration by curve estimation. Logistic regression was used to evaluate the association between aMCI and sleep duration.

In the analysis, there were no results proving that sleep duration in youth (P = 0.719, sleep duration < 10 hours; P = 0.999, sleep duration ≥ 10 hours) or midlife (P = 0.898, sleep duration < 9 hours; P = 0.504, sleep duration ≥ 9 hours) had a significant association with aMCI. In the group sleeping less than 7 hours in late life, each hour more of sleep duration was associated with approximately 0.80 of the original risk of aMCI (P = 0.011, odds ratio = 0.80, 95% confidence interval = 0.68–0.95).

Among the elderly sleeping less than 7 hours, there is a decreased risk of aMCI for every additional hour of sleep.

Based on a cohort from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), we aimed to evaluate the relationship between sleep duration and the incidence of cognitive impairment among older Chinese adults.

We conducted a prospective analysis based on 3692 participants from the CLHLS at baseline (in 2011), and as a 3-year follow-up (till 2014), 531 participants (14.4%) had cognitive impairment, which was defined as a Mini-Mental State Examination score <24. Sleep duration was classified into three groups: short (≤5 hours/day), normal (>5 but <10 hours), and long (≥10 hours/day). A logistic regression model was used to examine the association between baseline sleep duration and cognitive impairment after adjusting for sociodemographic data, living habits, and health conditions.

Five hundred sixty-two participants (15.2%) were in the short-duration group, and 608 participants (16.5%) were in the long-duration group. After adjusting for multiple potential confounders, compared with normal sleep duration, long sleep duration was associated with the incidence of cognitive impairment (OR = 1.309, 95% CI: 1.019–1.683), especially among men (OR = 1.527, 95% CI: 1.041–2.240) and those having a primary and above education level (OR = 1.559, 95% CI: 1.029–2.361). No significant association was observed between short sleep duration and cognitive impairment (OR = 0.860, 95% CI: 0.646–1.145).

Excessive sleep may increase the risk of cognitive impairment in older individuals. It may be a suggestive sign of early neurodegeneration and may be a useful clinical tool to identify those at a higher risk of progressing to cognitive impairment.

To assess the association between total alcohol intake, specific alcoholic beverages and sleep quality in a community-based cohort.

A cross-sectional study.

The Kailuan community, China.

Included were 11 905 participants who were free of a history of CVD, cancer, Parkinson’s disease, dementia and head injury in or prior to 2012. Alcohol consumption (amount and frequency intake) and alcoholic beverage type were collected in 2006 (baseline) and 2012. Participants were grouped into non-, light- (women: 0–0·4 serving/d; men: 0–0·9 serving/d), moderate- (women: 0·5–1·0 serving/d; men: 1·0–2·0 servings/d) and heavy- (women: >1·0 servings/d; men: >2·0 servings/d) drinkers. Overall sleep quality was measured in 2012 and included four sleep parameters (insomnia, daytime sleepiness, sleep duration, snoring/obstructive sleep apnoea).

We observed a dose–response association between higher alcohol consumption in 2006 and worse sleep quality in 2012 (Ptrend < 0·001), after adjusting for age, sex, socio-economic status, smoking status, physical activity, obesity, plasma lipid profiles, diabetes and hypertension. A similar association was observed when alcohol consumption in 2012 was used as exposure. Alcohol was associated with higher odds of having short sleep duration (adjusted OR for heavy- v. non-drinkers = 1·31; 95 % CI: 1·09, 1·57) and snoring (adjusted OR for heavy- v. non-drinkers: 1·38; 95 % CI: 1·22, 1·57). Consumption of hard liquor, but not beer or wine, was significantly associated with poor sleep quality.

Higher alcohol consumption was associated with poorer sleep quality and higher odds of having snoring and short sleep duration.

To test the associations between sleep indices and eating behaviours in young adults, a group vulnerable to suboptimal sleep.

Cross-sectional analysis of survey measures of sleep (i.e. time in bed, variability, timing and quality) and dietary patterns (i.e. breakfast skipping, eating at fast-food restaurants, consumption of sports and energy drinks, and sugar-free, sugar-sweetened and caffeinated beverages).

Minneapolis/St. Paul metropolitan area of Minnesota (USA).

A total of 1854 respondents (20–30 years, 55·6 % female) from the 2008–2009 survey conducted for the third wave of the population-based Project EAT (Eating and Activity in Teens and Young Adults) study.

After adjustment for demographic and behavioural covariates in linear regression models, those who went to bed after 00.30 hours consumed 0·3 more servings of sugar-sweetened beverages per day, consumed 1·7 times more energy drinks, skipped breakfast 1·8 more times per week and consumed fast food 0·3 more times per week compared with those who went to bed before 22.30 hours. Reported sleep quality in the lowest (Q1) v. highest (Q3) tertile was associated with more intake of energy drinks (Q3 v. Q1, prevalence ratio, 95 % CI: 1·79, 1·24, 2·34), sports drinks (1·28, 1·00, 1·55) and breakfast skipping (adjusted mean, 95 % CI: Q1: 4·03, 3·81, 4·26; Q3: 3·43, 3·17, 3·69). Time in bed and sleep variability were associated with few eating behaviours.

Some, but not all, sleep indices were related to problematic eating behaviours. Sleep habits may be important to address in interventions and policies that target improvements in eating patterns and health outcomes.

Aging is accompanied by cognitive decline that is escalated in older adults reporting extreme sleep duration. Social relationships can influence health outcomes and thus may qualify the association between sleep duration and cognitive function. The present study examines the moderating effects of marital status, household size, and social network with friends and relatives on the sleep–cognition association among older adults.

Data (N = 4,169) came from the Social Isolation, Health, and Lifestyles Survey, a nationally representative survey of community-dwelling older Singaporeans (≥ 60 years). Sleep duration and social relationships were self-reported. Cognitive function was assessed with the Short Portable Mental Status Questionnaire.

Regression analysis revealed that the inverted U-shaped association between sleep duration and cognitive function was less profound among older adults who were married (vs. unmarried) and those who had stronger (vs. weaker) social networks. In contrast, it was more prominent among individuals who had more (vs. fewer) household members.

Being married and having stronger social networks may buffer against the negative cognitive impact of extreme sleep duration. But larger household size might imply more stress for older persons, and therefore strengthen the sleep duration–cognitive function association. We discuss the potential biological underpinnings and the policy implications of the findings. Although our findings are based on a large sample, replication studies using objective measures of sleep duration and other cognitive measures are needed.

Durations of nocturnal sleep and daytime nap influence the well-being of older adults. It is thus essential to understand their determinants. However, much previous research did not assess sleep duration and nap duration individually, and longitudinal data is lacking. This study aimed at examining the impact of demographic, psychosocial, and health factors, including ethnicity, social networks outside the household, smoking and physical exercise on sleep duration and nap duration among community-dwelling elderly.

Our study involved over 2,600 older adults (≥60 years) from a longitudinal, nationally representative survey – the Panel on Health and Ageing of Singaporean Elderly. Sleep and nap durations at Time 2 (two years later) were regressed on predictors measured at Time 1.

Time 2 short nocturnal sleep duration was predicted by Malay ethnicity (relative to Chinese and Indian), older age, lower education level, more depressive symptoms, and obesity, whereas future long nocturnal sleep duration was predicted by weaker social networks, older age, and more chronic diseases. Furthermore, smoking, obesity, Malay or Indian (relative to Chinese), older age, male gender, and cognitive impairment predicted longer daytime nap duration in the future.

Older adults’ nocturnal sleep and daytime nap durations may be affected by different demographic, psychosocial, and health factors. Thus, it is important to differentiate these two attributes in this age group.

The objective of the present study was to investigate the association between salivary counts of mutans streptococci (MS) and children’s weight status, while considering associated covariates. MS ferments carbohydrates from the diet and contributes to caries by lowering the pH in dental plaque. In adults, high counts of MS in saliva have been associated with overweight, but this has not been shown in children.

Cross-sectional study investigating salivary counts of MS, BMI Z-score, waist circumference, meal frequency, sugar propensity and sleep duration, in children.

West Sweden.

Children (n 271) aged 4–11 years.

Medium–high counts of MS were positively associated with higher BMI Z-score (OR=1·6; 95 % CI 1·1, 2·3). Positive associations were also found between medium–high counts of MS and more frequent meals per day (OR=1·5; 95 % CI 1·1, 2·2), greater percentage of sugar-rich foods consumed (OR=1·1; 95 % CI 1·0, 1·3) and female sex (OR=2·4; 95 % CI 1·1, 5·4). A negative association was found between medium–high counts of MS and longer sleep duration (OR=0·5; 95 % CI 0·3, 1·0).

BMI Z-score was associated with counts of MS. Promoting adequate sleep duration and limiting the intake frequency of sugar-rich foods and beverages could provide multiple benefits in public health interventions aimed at reducing dental caries and childhood overweight.