Long sleep duration predicts a higher risk of obesity in adults: a meta-analysis of prospective cohort studies

Sedentary behavior, physical activity, sleep duration and obesity risk: Mendelian randomization study

BACKGROUND

Observational studies have suggested associations between sedentary behaviors (SB), physical activity (PA), sleep duration (SD), and obesity, but the causal relationships remain unclear.

METHODS

We used Mendelian randomization (MR) with genetic variation as instrumental variables (IVs) to assess the causality between SB/PA/SD and obesity. Genetic variants associated with SB/PA/SD were obtained from Genome-wide association study (GWAS), and obesity data came from FinnGen. The primary MR analysis used the instrumental variable weighted (IVW) method, with sensitivity tests including Cochran Q, MR-Egger intercepts, and MR-Radial. Expression Quantitative Trait Loci (eQTL) analysis was applied to identify significant genetic associations and biological pathways in obesity-related tissues.

RESULTS

The MR analysis revealed causal relationships between four SB-related lifestyle patterns and obesity. Specifically, increased genetic liability to television watching (IVW MR Odds ratio [OR] = 1.55, [95% CI]:[1.27, 1.90], p = 1.67×10-5), computer use ([OR] = 1.52, [95% CI]:[1.08, 2.13], p = 1.61×10-2), leisure screen time (LST) ([OR] = 1.62, [95% CI] = [1.43, 1.84], p = 6.49×10-14, and driving (MR [OR] = 2.79, [95% CI]:[1.25, 6.21], p = 1.23×10-2) was found to increase the risk of obesity. Our findings indicate that no causal relationships were observed between SB at work, sedentary commuting, PA, SD, and obesity. The eQTL analysis revealed strong associations between specific genes (RPS26, TTC12, CCDC92, NICN1) and SNPs (rs10876864, rs2734849, rs4765541, rs7615206) in both subcutaneous and visceral adipose tissues, which are associated with these SBs. Enrichment analysis further revealed that these genes are involved in crucial biological pathways, including cortisol synthesis, thyroid hormone synthesis, and insulin secretion.

CONCLUSIONS

Our findings support a causal relationship between four specific SBs (LST, television watching, computer use, driving) and obesity. These results provide valuable insights into potential interventions to address obesity effectively, supported by genetic associations in the eQTL and enrichment analysis. Further research and public health initiatives focusing on reducing specific SBs may be warranted.

Exposure to polycyclic aromatic hydrocarbons increases the risk of poor sleep pattern in US adults: results from the NHANES (2005-2010)

Recently, polycyclic aromatic hydrocarbons (PAHs) were found to be linked to various diseases. The current study's objective was to explore whether or not there was a relation between PAH exposure and poor sleep pattern. We evaluated nine urine PAH metabolites as exposures in our cross-sectional research based on the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2010. Logistic regression, restricted cubic spline regression (RCS) model, weighted quantile sum (WQS) regression, subgroup analysis, and mediation analysis were used to assess the associations between PAH metabolism and poor sleep pattern risk. After controlling for all confounding variables, several primary PAH metabolites, namely 1-hydroxynapthalene (1-NAP, OR 1.32, 95% CI 1.04-1.68), 2-hydroxyfluorene (2-FLU, OR 1.34, 95% CI 1.05-1.71), 1-hydroxyphenanthrene (1-PHE, OR 1.30, 95% CI 1.03-1.64), 9-hydroxyfluorene (9-FLU, OR 1.38, 95% CI 1.09-1.74), and ∑PAHs (OR 1.33, 95% CI 1.05-1.69), compared to the bottom tertile, were associated with increased risk of poor sleep pattern. The WQS regression analysis showed that 9-FLU and 1-NAP comprised the two most important factors related to poor sleep pattern. Mediation analysis revealed that inflammation acted as a mediator between PAHs and the prevalence of poor sleep pattern. In conclusion, exposure to PAHs may be associated with poor sleep pattern. Inflammation is a mediator of the effects of PAH exposure on poor sleep pattern.

The Relationships between Various Factors and Sleep Status: A Cross-Sectional Study among Healthy Saudi Adults

Impaired sleep can adversely affect daily life. This study assesses the association between different factors and sleep status among apparently healthy Saudi adults. In total, 478 adults were included in this study. Data on anthropometrics, body composition, stress scales, physical activity, and dietary habits were collected. Fasting blood glucose and lipid profile were measured. Sleep quality and duration were assessed using the Pittsburgh Sleep Quality Index. Larger neck circumference (NC) was associated with short sleep duration (odds ratio (OR) 1.23; 95% confidence interval (CI) [1.08, 1.41]; p = 0.002). Higher triglyceride levels were associated with poor sleep quality (OR 1.01; 95% CI [1.002, 1.02]; p = 0.019) and short sleep duration (OR 1.01; 95% CI [1.004, 1.02]; p = 0.005). Stress was a risk factor for poor sleep quality (OR 1.15; 95% CI [1.09, 1.22]; p < 0.001). Being married was significantly associated with good sleep quality (OR 2.97; 95% CI [1.32, 6.71]; p = 0.009), while being single was correlated with longer sleep duration (OR 0.46; 95% CI [0.22, 0.96]; p = 0.039). Other factors such as having a larger waist circumference and more muscle mass were protective factors against poor sleep quality and/or short sleep duration. In conclusion, a larger NC is suggested as a risk factor for short sleep duration and a higher triglyceride level for both short and poor sleep among healthy Saudis. Investigating the factors associated with sleep status may help alleviate sleep disturbances and improve overall health. Further studies are needed to confirm causality using objective sleep measures.

Associations between sleep and overweight/obesity in adolescents vary by race/ethnicity and socioeconomic status

AIM

To examine the interaction between sleep and social determinants of health (SDOH) [race/ethnicity and socioeconomic status (SES)] on overweight/obesity in adolescents.

DESIGN

Cross-sectional.

METHODS

We conducted a secondary analysis using the 2017-2018 National Survey of Children's Health data. We included adolescents (10-17 years old) who had sleep and body mass index (BMI) data available (n = 24,337) in analyses (samples with BMI <5th percentile excluded). Parents reported children's sleep duration and regularity. High BMI (≥85th percentile) for age defines overweight/obesity. We selected SDOH (race/ethnicity, family income, primary caregiver education and neighbourhood condition) and covariates (age, sex, smoking, exercise and depression) using a hierarchical model-building approach. Accounting for complex survey design, logistic regression estimated the interaction between sleep and SDOH.

RESULTS

There were significant interactions between sleep duration and SDOH. The association between increasing sleep and decreasing odds of overweight/obesity only showed in the following subgroups: White, family income ≥400% federal poverty level (FPL) or primary caregiver' education ≥ high school. Compared with these subgroups, Hispanic adolescents and adolescents whose family income was below 100% FPL and whose caregiver education was below high school had weakened and reversed associations. Sleep regularity was not associated with overweight/obesity.

CONCLUSIONS

Increasing sleep duration was associated with a decreased risk of overweight/obesity, but the association was not present in adolescents from racial/ethnic minority groups (i.e. Hispanic) and those with low SES.

IMPACT

The study findings suggest that associations between sleep and overweight/obesity vary by race and SES. Identification of additional mechanisms for obesity is needed for racial/ethnic minority groups and those from families with low SES. Also, the complexity of these relationships underscores the importance of community-based needs assessment in the design of targeted and meaningful interventions to address complex health conditions such as poor sleep and obesity.

Longitudinal associations between sleep and BMI in a low-income, predominantly Black American sample

OBJECTIVE

Black individuals and those experiencing socioeconomic disadvantage are at increased risk for sleep problems and obesity. This study adds to the limited extant literature examining longitudinal associations between objectively measured sleep and changes in body mass index (BMI) in Black Americans.

DESIGN

We focused on individuals with at least 1 observation of sleep and BMI at 1 of 3 study time points (2013, 2016, and 2018). We modeled longitudinal trends in BMI as a function of time, average of each sleep variable across assessments, and within-person deviations in each sleep variable over time.

SETTING

Data were collected via interviewer-administered at-home surveys and actigraphy in Pittsburgh, PA.

PARTICIPANTS

Our sample comprised 1115 low-income, primarily Black adults, including 862 women and 253 men.

MEASUREMENTS

Sleep measures included actigraphy-measured total sleep time, sleep efficiency, and wakefulness after sleep onset, as well as self-reported sleep quality. We also included objectively measured BMI.

RESULTS

In models adjusted for age, gender, and other sociodemographic covariates (eg, income, marital status), there were no significant longitudinal associations between total sleep time, sleep efficiency, wakefulness after sleep onset, or subjective sleep quality and changes in BMI.

CONCLUSIONS

This study provides further evidence that, among a sample of low-income Black adults, sleep problems are not longitudinally predictive of BMI. Although ample cross-sectional evidence demonstrates that sleep problems and obesity commonly co-occur, longitudinal evidence is mixed. Better understanding the overlap of sleep and obesity over time may contribute to prevention and intervention efforts.

Altered motivation states for physical activity and 'appetite' for movement as compensatory mechanisms limiting the efficacy of exercise training for weight loss

Weight loss is a major motive for engaging in exercise, despite substantial evidence that exercise training results in compensatory responses that inhibit significant weight loss. According to the Laws of Thermodynamics and the CICO (Calories in, Calories out) model, increased exercise-induced energy expenditure (EE), in the absence of any compensatory increase in energy intake, should result in an energy deficit leading to reductions of body mass. However, the expected negative energy balance is met with both volitional and non-volitional (metabolic and behavioral) compensatory responses. A commonly reported compensatory response to exercise is increased food intake (i.e., Calories in) due to increased hunger, increased desire for certain foods, and/or changes in health beliefs. On the other side of the CICO model, exercise training can instigate compensatory reductions in EE that resist the maintenance of an energy deficit. This may be due to decreases in non-exercise activity thermogenesis (NEAT), increases in sedentary behavior, or alterations in sleep. Related to this EE compensation, the motivational states associated with the desire to be active tend to be overlooked when considering compensatory changes in non-exercise activity. For example, exercise-induced alterations in the wanting of physical activity could be a mechanism promoting compensatory reductions in EE. Thus, one's desires, urges or cravings for movement-also known as "motivation states" or "appetence for activity"-are thought to be proximal instigators of movement. Motivation states for activity may be influenced by genetic, metabolic, and psychological drives for activity (and inactivity), and such states are susceptible to fatigue-or reward-induced responses, which may account for reductions in NEAT in response to exercise training. Further, although the current data are limited, recent investigations have demonstrated that motivation states for physical activity are dampened by exercise and increase after periods of sedentarism. Collectively, this evidence points to additional compensatory mechanisms, associated with motivational states, by which impositions in exercise-induced changes in energy balance may be met with resistance, thus resulting in attenuated weight loss.

Sex-specific correlates of metabolic syndrome risk in college-aged young adults

Objective: To identify the sex-specific prevalence of metabolic syndrome (MetS) risk factors and their physiological, psychosocial, and behavioral correlates in a college-aged population. Participants and methods: Cross-sectional assessment of MetS risk factors and potential correlates occurred in 379 first-year students (aged 18.34 ± 0.49 years, 67.3% female). Multivariable linear regression assessed the relationships between potential correlates and continuous MetS risk scores, derived from principal component analysis. Results: MetS risk factors were present in 58.4% of females and 68.5% of males, with 2.4% and 3.2% having defined MetS. In females, percent body fat (β = 0.46, p < 0.001), stress (β = 0.12, p = 0.031), % kcal from sugar (β = 0.18, p = 0.001), and moderate-to-vigorous physical activity (β=-0.12, p = 0.036) were associated with risk score. Whereas, correlates in males included percent body fat (β = 0.54, p < 0.001), C-reactive protein (β = 0.15, p = 0.045), and AUDIT alcohol consumption score (β = 0.15, p = 0.033). Conclusion: The sex-specific prevalence of MetS risk factors and correlates suggest that primary prevention strategies on college campuses should also follow a sex-specific approach.

Effect of sleep on weight loss and adherence to diet and physical activity recommendations during an 18-month behavioral weight loss intervention

BACKGROUND/OBJECTIVES

To examine the association between indices of sleep quantity and quality with dietary adherence, physical activity adherence, and weight loss during a behavioral weight loss intervention.

METHODS

Adults (n = 156) with overweight and obesity (40 ± 9 years, 84% female, BMI: 34.4 ± 4.2 kg/m²) participated in an 18-month behavioral weight loss intervention which prescribed a reduced calorie diet (1200-1800 kcal/d) and increased physical activity (300 min/wk). Body weight, indices of sleep (SenseWear armband; SWA), energy intake (EI, 3-day food records), and moderate-to-vigorous physical activity (SWA) were measured at baseline, 6, 12, and 18 months. Linear mixed effects models examined the association between sleep and weight change over time. Additional models were adjusted for covariates including age, BMI, sex, race, ethnicity, study completion, randomization, EI, and physical activity. Secondary analyses examined the association between sleep and adherence to diet and physical activity recommendations.

RESULTS

Mean weight loss was 7.7 ± 5.4, 8.4 ± 7.9, and 7.1 ± 9.0 kg at 6, 12, and 18 months, respectively. Lower sleep efficiency, higher wake after sleep onset (WASO), more awakenings, and higher sleep onset latency (SOL) were significantly associated with attenuated weight loss (p < 0.05). Lower sleep efficiency, more awakenings, and higher SOL remained significantly associated with blunted weight loss after adjustment for covariates (p < 0.05). Later waketime, longer time in bed, longer sleep duration, higher WASO, more awakenings, and higher SOL were associated with lower odds of achieving ≥300 min/wk of moderate-to-vigorous physical activity, adjusted for covariates (FDR p < 0.05).

CONCLUSIONS

Future studies should evaluate whether incorporating strategies to improve sleep health within a behavioral weight loss intervention leads to improved adherence to diet and physical activity recommendations and enhanced weight loss.

CLINICAL TRIALS IDENTIFIER

NCT01985568.

Impact of the Intake of Snacks and Lifestyle Behaviors on Obesity among University Students Living in Jeddah, Saudi Arabia

Unhealthy eating habits increase the risk of obesity. This study investigated the association between obesity and the intake of snacks and lifestyle behaviors among university students in Saudi Arabia. The study included 662 students aged 18–29 years, studying at King Abdulaziz University. An online survey collected data on sociodemographic characteristics, height, and weight, to calculate body mass index (BMI), lifestyle behaviors, dietary habits, and snack intake. The prevalence of overweight and obese students was 18.6% and 12.7%, respectively. Sociodemographic characteristics and lifestyle behaviors had insignificant effects on obesity. Obese students consumed two meals daily and more cereals during breakfast. Non-obese students consumed more beverages at breakfast and had their daily meals with their families. The frequency of intake of snacks had an insignificant effect on obesity. However, obese students had a significantly higher intake of potato chips, popcorn, and biscuits, while non-obese students had a significantly higher intake of salads compared with obese students. Students consumed significantly less fruit and vegetables, chocolate, biscuits, nuts, and dairy products as snacks when inside the university compared to outside. To reduce obesity among students, universities should ensure access to healthy snacks, and provide health education programs to encourage healthy eating habits and lifestyles.

Age and Sex Differences in the Association of Sleep Duration and Overweight/Obesity among Chinese Participants Age above 45 Years: A Cohort Study

OBJECTIVES

We aimed to evaluate the association between sleep duration and obesity and estimate the attributable risk of sleep in the China Health and Retirement Longitudinal Study surveys (CHARLS).

METHODS

A total of 9061 adults aged 45 years above from CHARLS (2011-2015) were included. The main outcome of this study was incident overweight/obesity specific to general and abdominal obesity. Overweight/obesity was defined as BMI ≥ 23.0 (kg/m2) and BMI≥27.5 (kg/m2), respectively. Abdominal obesity was defined as waist circumference ≥90 cm for men and ≥80 cm for women. Self-reported sleep durations were obtained using a structured questionnaire. We assessed hazard ratios (HRs) and 95% confidence intervals (CIs) as well as the population attributable fraction (PAF) for associations between sleep duration and obesity.

RESULTS

986 and 606 participants were identified as overweight and general obesity respectively, 1253 experienced abdominal obesity events. In multivariable-adjusted models, participants with daytime sleep of 0-30 minutes and more than 30 minutes associated with 30% (HR: 0.70, 95% CI: 0.56-0.87) and 35% (HR: 0.65, 95% CI: 0.55-0.78) decreased incident overweight risk respectively compared to those having no daytime sleep, this association also found among females and middle-aged, not males or elderly. Similarly, 0-30 minutes (HR: 0.68, 95% CI: 0.48-0.96) and more than 30 minutes of daytime sleep (HR: 0.73, 95% CI: 0.59-0.91) were associated with a reduced risk of abdominal obesity, similar results also found among females and middle-aged. Compared with 7-9 hours of nocturnal sleep, people who slept 5-7 hours had a reduced risk of overweight (HR: 0.59, 95% CI=0.47-0.74),but not found in subgroups. The hazard role of long nocturnal sleep for abdominal obesity was only found among elderly (HR: 2.33, 95% CI=1.35-4.04) and males (HR: 2.24, 95% CI=1.17-4.29). Compared with moderate total sleepers (7-9hours/day), participants with short total sleep duration exhibited an elevated risk of overweight (HR: 1.13, 95% CI=1.00-1.28), this also found among middle-aged. The PAF for inadequate total sleep duration (<7 hours/day) was 10.77% for overweight individuals.

CONCLUSIONS

Insufficient sleep duration was associated with an elevated risk of overweight only detected among middle-aged not elderly and other subgroups specific by age. The risks for abdominal obesity were increased for males and middle-aged with long nocturnal sleep. Daytime sleep may significantly reduce the risk of overweight and abdominal obesity in female and middle-aged individuals. The link between sleep duration and obesity requires further study.

Sleep duration and health outcomes: an umbrella review

PURPOSE

To collect existing evidence on the relationship between sleep duration and health outcomes.

METHODS

A thorough search was conducted in PubMed, Web of Science, Embase, and the Cochrane Database of Systematic Reviews from inception to January, 2021. Meta-analyses of observational and interventional studies were eligible if they examined the associations between sleep duration and human health.

RESULTS

In total, this umbrella review identified 69 meta-analyses with 11 outcomes for cancers and 30 outcomes for non-cancer conditions. Inappropriate sleep durations may significantly elevate the risk for cardiovascular disease (CVD), cognitive decline, coronary heart disease (CHD), depression, falls, frailty, lung cancer, metabolic syndrome (MS), and stroke. Dose-response analysis revealed that a 1-h reduction per 24 hours is associated with an increased risk by 3-11% of all-cause mortality, CHD, osteoporosis, stroke, and T2DM among short sleepers. Conversely, a 1-h increment in long sleepers is associated with a 7-17% higher risk of stroke mortality, CHD, stroke, and T2DM in adults.

CONCLUSION

Inappropriate sleep duration is a risk factor for developing non-cancer conditions. Decreasing and increasing sleep hours towards extreme sleep durations are associated with poor health outcomes.

Short Sleep Duration and Its Association with Obesity and Other Metabolic Risk Factors in Kuwaiti Urban Adults

BACKGROUND

Efficient sleep duration and its quality are increasingly recognized as important contributors for maintaining normal body weight. However, lifestyle and social structure within the Arab-gulf region differ compared to those in the western world. This study was specifically conducted in Kuwait's population to investigate the link between sleep quality (SQ) and obesity in the absence of sleep apnea (SA) onset.

METHODS

SQ was measured by the Pittsburgh Sleep Quality Index (PQSI) in 984 participants, then verified in 60 individuals including 20 lean (Body mass index/BMI: 18.5-24.9 kg/m²), 20 overweight (BMI: 25-29.9 kg/m²) and 20 obese (BMI: ≥30 kg/m²) through actigraph worn over the right-hip for 7 consecutive days to characterize their sleep-wake cycle, rest-activity, and physical activity. Blood samples were collected for metabolic markers.

RESULTS

59.6% of participants reported a PSQI score higher than 5, with 57.6% of the participants reporting less than 6 hours of sleep per day. The data show that both SQ and sleep duration are considered inadequate in comparison to the international SQ standards. We found a significant association between SQ and obesity independent of age and sex. Actigraph data further supported the independent association of sleep duration on BMI within the population (p < 0.001). Additionally, total sleep time (TST) was found to significantly correlate with several other metabolic factors including diastolic blood pressure, elevated resting heart rate (RHR), triglycerides, total cholesterol, homeostatic model assessment for insulin resistance (HOMA-IR), C-peptide, and C-Reactive Protein (CRP) secretion. Further multiple-regression analysis showed a significant independent association between blood pressure (p < 0.03), HOMA-IR (p < 0.04), and C-peptide (p < 0.3) and sleep duration.

CONCLUSION

These findings suggest that sleep deprivation and disturbance could be indirect factors involved in the development of not only obesity in Kuwait but also other metabolic syndromes such as type 2 diabetes.

Obesity and sleep mismatch between weekends and weekdays in the Korean population according to working status

OBJECTIVES

To investigate whether sleep mismatch between weekends and weekdays is correlated with obesity according to working status and sex in the Korean population.

STUDY DESIGN

This study was conducted using data from the Korea National Health and Nutritional Examination Survey (KNHANES) in 2016. A total of 5,684 subjects (2,453 men and 3,231 women) were divided into subgroups according to age, sex and working status. Sleep mismatch was defined as the difference in sleep duration between weekdays and weekends. In this study, multivariable logistic regression analysis was applied to obtain odds ratios (ORs) for obesity in those with sleep mismatch ≥ 90 min when referenced to those with sleep mismatch < 90 min.

MAIN OUTCOME MEASURES

In the working group, adjusted ORs for obesity were mostly less than 1, but they were not statistically significant among any age or sex groups. However, for the non-working group, men over 60 years of age with sleep mismatch ≥ 90 min showed significantly increased ORs when referenced to those with sleep mismatch < 90 min in every model; the OR in model 4 was 2.89. Women over 60 years of age with sleep mismatch ≥ 90 min also showed higher ORs but they were not statistically significant.

CONCLUSIONS

Men who are not working and over 60 years of age in Korea may be at increased risk of obesity if their sleep mismatch is ≥ 90 min. Therefore, it might be possible to lower the prevalence of obesity in the elderly population by correcting sleep irregularity or through reemployment.

Lifestyle interventions for the prevention and treatment of hypertension

Hypertension affects approximately one third of the world's adult population and is a major cause of premature death despite considerable advances in pharmacological treatments. Growing evidence supports the use of lifestyle interventions for the prevention and adjuvant treatment of hypertension. In this Review, we provide a summary of the epidemiological research supporting the preventive and antihypertensive effects of major lifestyle interventions (regular physical exercise, body weight management and healthy dietary patterns), as well as other less traditional recommendations such as stress management and the promotion of adequate sleep patterns coupled with circadian entrainment. We also discuss the physiological mechanisms underlying the beneficial effects of these lifestyle interventions on hypertension, which include not only the prevention of traditional risk factors (such as obesity and insulin resistance) and improvements in vascular health through an improved redox and inflammatory status, but also reduced sympathetic overactivation and non-traditional mechanisms such as increased secretion of myokines.

Association of sleep quality and sleep duration with serum uric acid levels in adults

OBJECTIVE

To date, the association between sleep duration or sleep quality and hyperuricemia has remained unclear. In addition, sleep duration and quality were not considered concomitantly in previous studies. Thus, this study was aimed toward an examination of the association of sleep duration and quality with uric acid level in a Taiwanese population.

METHODS

A total of 4,555 patients aged ≥18 years were enrolled in this study. The sleep duration was classified into three groups: short (<7 h), normal (7-9 h), and long (≥9 h). The Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality, and poor sleep quality was defined as a global PSQI score of >5.

RESULTS

Poor sleepers were younger and had lower body mass index, blood pressure, uric acid, blood sugar, cholesterol, creatinine level, shorter sleep duration, and engaged in less exercise but had a higher white blood cell count and prevalence of smoking as compared to good sleepers. There were also differences in body mass index, blood pressure, uric acid, blood sugar, lipid profiles, and sleep quality among subjects with different sleep durations. After adjusting for other variables, poor sleep quality was associated with lower uric acid levels. In addition, short sleep duration was positively associated with higher uric acid levels.

CONCLUSIONS

Poor sleep quality was related to lower uric acid levels, whereas short sleep duration was associated with higher uric acid levels.

Sleep and Obesity: Mechanisms of Association

Epidemiologic studies demonstrate that both prolonged and reduced sleep duration is associated with increased risk of excessive weight and obesity. The aim of the review was to analyze probable mechanisms of association of sleep duration and obesity elucidated in current scientific literature. Several proposed mechanisms of such an association exist: an imbalance of appetite regulating hormones resulting from decreased sleep duration; fatigue or decreased activity during the daytime, leading to sedentary behavior with decreased energy expenditure; changes in eating behavior with increased daily calorie intake. The article gives a comprehensive review of factors, mediating the association of sleep duration and obesity (age, gender, ethnic origin), studies of neurohormonal regulation of sleep in association with obesity (the influence of sleep duration on thermoregulation, appetite center – increased grelin-to-leptin ratio); the relationship of sleep with growth hormone and insulin-like growth factor-1, with hypothalamic-pituitary-adrenal axis, and non-hormonal factors, stimulating food intake. Data indicating that increased sleep duration is often associated with decreased sleep quality are presented. Besides traditional risk factors – unhealthy diet and decreased physical exercise, specific attention should be given to the problems, associated with sleep disorders to increase the efficacy of treatment and prevention of obesity.

Exploring Relationships of Sleep Duration with Eating and Physical Activity Behaviors among Canadian University Students

BACKGROUND

Students pursuing postsecondary education are a population described as vulnerable for sleep problems, poor dietary habits, weight gain, and reduced physical activity. The primary goal of this study was to examine relationships of sleep behaviors with eating and physical activity behaviors in a sample of undergraduate health sciences students.

METHODS

Using a cross-sectional design, undergraduate health sciences students in a small Canadian university were recruited to complete an on-line questionnaire about their sleep, eating, and physical activity behaviors using valid and reliable instruments. Key sociodemographic characteristics and self-reported height and weight data were also captured.

RESULTS

The participants (n = 245) were on average 23 years of age, female (86%), and the majority were full-time students (92%). The mean BMI was within a healthy range (mean 24.58 SD 5.55) with the majority reporting low physical activity levels (65%). Despite self-reports of very or fairly good (65%) sleep quality in the past month, the mean global sleep scores (scores > 5, mean 7.4, SD 3.3) indicated poor overall sleep quality. Poorer sleep quality was associated with higher BMIs (r = 0.265, p < 0.001).

CONCLUSIONS

The findings highlight the need to expand the scope of on-campus wellness programs to promote healthy sleep habits in a vulnerable university population.

Delayed sleep-onset and biological age: late sleep-onset is associated with shorter telomere length

STUDY OBJECTIVES

We evaluated the relationship between leukocyte telomere length (LTL) and sleep duration, insomnia symptoms, and circadian rhythm, to test whether sleep and chronobiological dysregulations are associated with cellular aging.

METHODS

Data from the Netherlands Study of Depression and Anxiety (N = 2,936) were used at two waves 6 years apart, to measure LTL. Telomeres shorten during the life span and are important biomarkers for cellular aging. LTL was assessed by qualitative polymerase chain reaction and converted into base pair number. Sleep parameters were: sleep duration and insomnia symptoms from the Insomnia Rating Scale. Circadian rhythm variables were: indication of Delayed Sleep Phase Syndrome (DSPS), mid-sleep corrected for sleep debt on free days (MSFsc), sleep-onset time, and self-reported chronotype, from the Munich Chronotype Questionnaire. Generalized estimating equations analyzed the associations between LTL, sleep, and chronobiological factors, adjusted for baseline age, sex, North European ancestry, and additionally for current smoking, depression severity, obesity, and childhood trauma.

RESULTS

Indicators of delayed circadian rhythm showed a strong and consistent effect on LTL, after adjustment for sociodemographic and health indicators. Late MSFsc (B = -49.9, p = .004), late sleep-onset time (B = -32.4, p = .001), indication of DSPS (B = -73.8, p = .036), and moderately late chronotype in adulthood (B = -71.6, p = .003) were associated with significantly shorter LTL across both waves; whereas sleep duration and insomnia symptoms were not. Extremely early chronotype showed significantly less LTL shortening than intermediate chronotype (B = 161.40, p = .037). No predictors showed accelerated LTL attrition over 6 years.

CONCLUSIONS

Individuals with delayed circadian rhythm have significantly shorter LTL, but not faster LTL attrition rates.

Bridging the Reciprocal Gap between Sleep and Fruit and Vegetable Consumption: A Review of the Evidence, Potential Mechanisms, Implications, and Directions for Future Work

A substantial burden of disease and mortality globally is attributable to both sleep disruption and low intakes of fruit and vegetable (FV) and there is increasing mechanistic and epidemiological evidence to support a reciprocal relationship between the two. This review provides an overview of experimental and observational studies assessing the relations between sleep and FV consumption from 52 human adult studies. Experimental studies are currently limited and show inconsistent results. Observational studies support a non-linear association with adults sleeping the recommended 7–9 hours/day having the highest intakes of FV. The potential mechanisms linking sleep and FV consumption are highlighted. Disrupted sleep influences FV consumption through homeostatic and non-homeostatic mechanisms. Conversely, FV consumption may influence sleep through polyphenol content via several potential pathways. Few human experimental studies have examined the effects of FV items and their polyphenols on sleep and there is a need for more studies to address this. An appreciation of the relationship between sleep and FV consumption may help optimize sleep and FV consumption and may reduce the burden of chronic diseases. This review provides implications for public health and directions for future work.