Inadequate sleep as a contributor to obesity and type 2 diabetes.

Epidemiological studies suggest that adults and children who are habitual short sleepers tend to have a higher body mass index, fat percentage and abdominal circumference when compared to average-duration sleepers. Reduced or disturbed sleep is also associated with certain predictors of type 2 diabetes, such as glucose intolerance, insulin resistance, reduced insulin response to glucose and a reduction in the disposition index. Current experimental evidence suggests that sleep restriction may lead to increased food intake but does not appear to result in decreased energy expenditure. Furthermore, sleep restriction has been reported to increase evening cortisol levels, which may decrease insulin sensitivity the next morning. This notion was further supported by studies, which noted decreases in the effectiveness of insulin-mediated glucose uptake the following morning. Further evidence suggests that short sleepers have glucose responses that are similar to average-duration sleepers, but at the cost of an increase in insulin release, which may be the result of decreased insulin sensitivity over time. Recent studies also provide evidence that sleep restriction enhances susceptibility to food stimuli, especially for energy-dense, high-carbohydrate foods. In summary, inadequate sleep, in both quality and quantity, should be regarded as a plausible risk factor for the development of obesity and type 2 diabetes. In addition to other health promotion measures, a good night's sleep should be seen as a critical health component by clinicians in the prevention and treatment of obesity and type 2 diabetes.