This research shows that shorter sleep duration disturbs normal metabolism, which may contribute to obesity, insulin resistance, diabetes, and cardiovascular disease. Even two to three nights of shortened sleep can have profound effects, the laboratory data suggest.
One study indicated that insufficient sleep at the age of 30 months was associated with obesity at the age of 7, suggesting that this could programme the part of the brain regulating appetite and energy expenditure, says Dr Taheri.
Another piece of research shows that levels of leptin, a hormone produced by fat tissue when energy stores are low, were more than 15% lower in those sleeping five hours compared with those clocking up 8.
Similarly, ghrelin, a hormone released by the stomach to signal hunger was almost 15% higher in those with a five hour sleep quota.
Sleep loss also disturbs other hormones, including insulin, cortisol (stress hormone), and growth hormone, says Dr Taheri, who adds that hormonal changes could boost the desire for carlorie rich foods.
And poor sleep sets up a vicious cycle. It leads to fatigue, which leads to reduced levels of physical activity….which leads to lower energy expenditure…..which leads to obesity, which itself leads to poor sleep, he adds.
Dr Taheri acknowledges that the mechanisms behind obesity are likely to be complex. “Sleep is probably not the only answer to the obesity pandemic, but its effect should be taken seriously, as even small changes in energy balance are beneficial,” he says.
Related: Sleep yourself skinny:
An interesting article has recently come out in the journal, Obesity Reviews. In it the authors talk about how much weight you can lose by just adding 1 more hour of sleep to your day.