Sleep and Obesity

Many studies showed that there is a link between sleep loss and obesity - a significant association between short sleep (generally less than 6 hours per night) and increased obesity risk. In other words, short sleep duration is a risk factor for the development of obesity. And the converse is true. For example, in Italy, a six year study on 1,597 respondents found that every additional hour of sleep decreased the incidence of obesity by 30 per cent.

This is because sleep is an important modulator of neuroendocrine function and glucose metabolism. Sleep loss results in metabolic and endocrine alterations. This includes decreased glucose tolerance and alteration of appetite regulating hormone. 

Ghrelin, a hormone promoting hunger, increases with sleep restriction whereas leptin, a hormone contributing to satiety perception, decreases. And leptin by itself increases energy expenditure. Therefore changes in leptin after sleep deprivation would affect both caloric intake and energy expenditure.

And so excessive food intake associated with insufficient sleep accounts for the increase in obesity risk.

To make the matter worse, severe obesity, in turn, appears to be associated with marked sleep disturbances. Such sleep disturbances may equally predispose severely obese individuals to accumulate a sleep debt and may contribute to the dysregulation of appetite, limit the drive for physical activity and further compromise weight maintenance.