Sleep deprivation and human energy metabolism

Abstract

Driven by the demands and opportunities of modern life many people now sleep less than 6 hrs per night. In the sleep clinic, this behavior may present as a diagnosis of insufficient sleep syndrome (ICSD-9, #307.49-4) which is receiving increased attention as a potential risk factor for obesity and related metabolic morbidity. A central theme of this chapter is the notion that extended wakefulness has higher metabolic cost, which triggers a set of neuroendocrine (e.g. more hunger and less satiety), metabolic (e.g. lower resting metabolic rate), and behavioral (e.g. reduced daily activity) adaptations aimed at increasing food intake and conserving energy. Although this coordinated response may have evolved to offset the metabolic demands of sleeplessness in natural habitats with limited food availability, it can become maladaptive in a modern environment which allows many to overeat while maintaining a sedentary lifestyle without sufficient sleep. Growing experimental evidence now suggests that such sleep-loss-related metabolic adaptation could: (a) lead to increased retention of fat when people aim to return to their usual weight after various life events associated with excessive food intake; and (b) undermine the success of therapies combining reduced food intake and increased physical activity to decrease metabolic risk in obesity-prone individuals. Emerging observational and clinical trial data are consistent with this experimental framework, making it prudent to recommend that overweight and obese individuals attempting to reduce their caloric intake and maintain increased physical activity should obtain adequate sleep and seek effective treatment for any coexisting sleep disorders.