Obesity is a major public health epidemic worldwide in children and adults (1-6). The prevalence and severity of childhood obesity is dramatically increasing with a corresponding increase in the prevalence of obesity-related morbidities particularly those involving obstructive sleep apnea and metabolic and cardiovascular sequelae (7). Prevention of childhood obesity is an urgent issue for public health, in particular, in many industrialized countries and some transition societies. Nutrition and physical activity (PA) have been the major research focus on obesity prevention (8-11). However, most published findings of such interventions suggested little success in preventing childhood obesity (6,12), although some that focused on dietary or/and PA approaches have showed some desirable impact on BMI status (13). Other risk factors, such as sleep, may be related to obesity, although sleep behavior has received much less attention than dietary intake and PA (14,15).Sleep, like PA and diet, plays an important role in the growth, maturation, and health of children and adolescents by allowing for the diurnal rhythm of hormones related to growth, maturation, and energy homeostasis (16). A number of biological mechanisms have been proposed to link sleep duration and obesity (17). For example, one theory posits that children with short sleep have low caloric intake and expenditure, given that sleep deprivation often leads to changes in the structure of sleep stage and results in fatigue, daytime sleepiness, somatic and cognitive problems, and low activity levels (18,19). Previous studies indicate that sleep deprivation results in changes in levels of several hormones including leptin, ghrelin, insulin, cortisol, and growth hormone (20)(21)(22). These hormonal changes may contribute to energy imbalance and then lead to overweight or obesity.Recently, there is increasing epidemiological evidence suggesting a link between sleep duration and obesity in children (18,(23)(24)(25)(26), adolescents (27), and adults (28-30). In adults, some studies indicate a negative association between sleep duration and obesity/BMI in men and a U-shaped relation between sleep duration and BMI in women (29). Several epidemiological studies have examined the association between short sleep duration and obesity in children and adolescents (18,(23)(24)(25)(26)(27)(31)(32)(33)(34)(35)(36)(37), but the reported findings are inconsistent (18,32,35,37). A recent review summarized 13 studies that examined the association between short sleep duration and obesity among children and adolescents, and recommended more sleep to prevent obesity (17). However, the review suffered from several limitations including misclassification of the design of some studies and included a study with adults as the primary age group (28). Several related previous studies were not included. Furthermore, new studies have been reported since the publication of the review. A major gap in the related literature is that to our knowledge, no metaanalyses have been conducted to examin...

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The authors evaluated the prognostic effects of obesity and weight change after breast cancer diagnosis. A total of 5042 breast cancer patients aged 20–75 were identified through the population-based Shanghai Cancer Registry approximately 6 months after cancer diagnosis and recruited into the study between 2002 and 2006. Participants were followed by in-person interviews supplemented by record linkage with the Shanghai Vital Statistics Registry database. Anthropometric measurements were taken and information on sociodemographic, clinical, and lifestyle factors was collected through in-person interviews. During the median follow-up of 46 months, 442 deaths and 534 relapses/breast cancer-specific deaths were documented. Women with body mass index (BMI) ≥30 at diagnosis had higher mortality than women with 18.5≤BMI<25; the multivariate adjusted hazard ratios (HRs) were 1.55 (95% confidence interval (95% CI): 1.10–2.17) for total mortality and 1.44 (95% CI: 1.02–2.03) for relapse/disease-specific mortality. Similar results were found for pre- and post-diagnostic obesity. Women who gained ≥5kg or lost >1kg had higher mortality than those who maintained their weight. No association was observed between waist-to-hip ratio and mortality. Our study suggests that obesity and weight change after diagnosis are inversely associated with breast cancer prognosis. Weight control is important among women with breast cancer.

It has been suggested that exercise following breast cancer diagnosis is inversely associated with mortality. However, controversy exists regarding the causality of such associations. We evaluated associations of exercise after breast cancer diagnosis with total mortality and recurrence/disease-specific mortality after accounting for conditions that restrict exercise participation. The analysis included 4826 women with stage I–III breast cancer identified 6 months after diagnosis through the population-based Shanghai Cancer Registry and recruited into the study between 2002 and 2006. Exercise was assessed approximately 6, 18, and 36 months post-diagnosis and metabolic equivalent (MET) scores were derived. Information on medical history, cancer diagnosis, treatments, quality of life (QOL), anthropometrics, and lifestyles were obtained by in-person interviews at 6 months post-diagnosis. Medical charts were abstracted to verify clinical information. During the median follow-up of 4.3 years, 436 deaths and 450 recurrences/cancer-related deaths were documented. After adjustment for QOL, clinical prognostic factors, and other covariates, exercise during first 36 months post-diagnosis was inversely associated with total mortality and recurrence/disease-specific mortality with hazard ratios of 0.70 (95% confidence interval (CI): 0.56–0.88) and 0.60 (95% CI: 0.47–0.76), respectively. Significant dose-response relationships between total and recurrence/disease-specific mortality rates and exercise duration and MET scores were observed (all Ptrend<0.05). The exercise-mortality associations were not modified by menopausal status, comorbidity, QOL, or body size assessed approximately 6 months post-diagnosis. An interaction between disease stage and hormone receptor status and total mortality was noted. Our study suggests that exercise after breast cancer diagnosis may improve overall and disease-free survival.