Insufficient sleep and healthy functioning
The findings of the present study are consistent with the literature that demonstrates that short sleep duration is closely related to overweight and obesity (2, 51–68). Although there are some theories to explain these associations such as calorie intake and fatigue (64), future studies should explore the relationship between sleep duration and BMI longitudinally to establish causation and to elucidate the underlying mechanisms. It should be noted that these results are consistent with a previous study that examined a subset of this same cohort and found that insufficient sleep was associated with obesity (19). In the study by Altman et al., the effect of insufficient sleep was accounted for by sleep duration, suggesting that it is short sleep, and not perceived sleep insufficiency per se that is related to obesity.