Is prolonged lack of sleep associated with obesity?

In the linked longitudinal study (doi:10.1136/bmj.d2712), Carter and colleagues assess the association between reduced sleep and differences in body composition and the risk of becoming overweight in young children.1

We spend about a third of our life asleep. We spend more time asleep as babies and children and then generally settle into a pattern of seven to eight hours a night. Sufficient sleep is necessary for optimal daytime performance and wellbeing, yet the amount of sleep that people get varies greatly.2

The quantity and quality of sleep have shown secular trends alongside changes in modern society that require longer hours of work, more shift work, and “24/7” availability of commodities. These changes have reduced the average duration of sleep across westernised populations, with increased reporting of fatigue, tiredness, and excessive daytime sleepiness.2 This sleep curtailment has been attributed mainly to lifestyle changes.2 Too little sleep is associated with adverse health outcomes, including total mortality,3 stroke and coronary heart disease,4 type 2 diabetes,5 hypertension,6 respiratory disorders, poor self rated health,2 and obesity in adults and children.7

Obesity in childhood has now reached epidemic proportions and is a cause of psychosocial problems including low self esteem. It often continues into adulthood, where it causes major morbidity, disability, and premature death. Several studies have reported associations between short duration of sleep …