Sleep-focused interventions: Investigating the effects of sleep restriction on energy balance

Abstract

Obesity has reached epidemic proportions, and excess body weight and adiposity have been linked to many adverse health conditions including various cancers. Rising obesity rates over the last few decades have been paralleled by concomitant reductions in nocturnal sleep duration, and epidemiological evidence has demonstrated a relationship between short sleep and increased weight gain and obesity. Causality cannot be inferred from these studies however, so laboratory-based interventions are essential to determine the nature of the short sleep-obesity link. The aim of this chapter is to summarize and evaluate the clinical intervention studies which altered sleep either by partially restricting sleep episode length or by completely eliminating the sleep episode to investigate the resulting effects on energy balance. Specific energy balance parameters considered include energy expenditure, subjective hunger/appetite ratings, appetite-regulating hormones, and food intake. Most studies support a role of short sleep in increasing food intake, but the results on energy expenditure, hunger, and hormonal regulation of food intake are less consistent. This chapter critically evaluates how methodological differences may contribute to discrepancies and inconsistencies between study results, with an emphasis on the roles of sex, the state of energy balance of study participants, and the timing of manipulated sleep schedules within the intervention studies.