Short sleep duration is considered a potential risk for overweight/obesity in childhood and adolescence. However, most of the evidence on this topic is obtained from cross-sectional studies; therefore, the nature and extent of the longitudinal associations are unclear. This study explores the prospective association between short sleep and overweight/obesity in young subjects. The MEDLINE, EMBASE, Pubmed, and CINAHL databases were searched for English-language articles, published until May 2014, reporting longitudinal association between sleep and body mass index (BMI) in children and adolescents. Recommendations of the Sleep Health Foundation were used to standardize reference sleep duration. Sleep category, with sleep duration less than the reference sleep, was considered as the short sleep category. Meta-analysis was conducted to explore the association between short sleep and overweight/obesity. A review of 22 longitudinal studies, with subjects from diverse backgrounds, suggested an inverse association between sleep duration and BMI. Meta-analysis of 11 longitudinal studies, comprising 24,821 participants, revealed that subjects sleeping for short duration had twice the risk of being overweight/obese, compared with subjects sleeping for long duration (odds ratio 2.15; 95% confidence interval: 1.64-2.81). This study provides evidence that short sleep duration in young subjects is significantly associated with future overweight/obesity.

Poor sleep quality seems to be associated with Ow/Ob, and some studies indicate this association to be independent of duration. Therefore, considering only sleep duration might not help in disentangling sleep-obesity association. However, this review is mostly composed of cross-sectional studies. Therefore, a causal link or the stability of the sleep quality and Ow/Ob association could not be established.

Objectives:To explore if gender difference in sleep quality is due to higher prevalence of depression in females, and whether socio-demographic and lifestyle factors have a differential effect on sleep quality in males and females.Methods: Youth self-reports and the Pittsburgh Sleep Quality Index were used to assess sleep quality and associated risk factors. Logistic regression analyses were used to analyze the association between various risk factors and poor sleep quality. Results:Reports from 3,778 young adults (20.6±0.86 years) indicate a higher prevalence of poor sleep quality in females than males (65.1% vs. 49.8%). It seems that gender difference in poor sleep is independent of depression, socio-demographics, and lifestyle factors, since the higher odds of poor sleep quality in females was robust to adjust for depression, socio-demographics, and lifestyle factors (OR: 1.53, 95% CI: 1.23-1.90). Lifestyle factors (eg, smoking) (OR 1.91; 95% CI 1.05-3.46) were associated with sleep quality in only males. Conclusion:Our findings indicate that female vulnerability to poor sleep quality should be explored beyond psycho-social disparities. Perhaps, exploring if the female predisposition to poor sleep quality originates at the biological level could lead to the answer.