Researchers found that adults younger than 40, those who typically slept for five hours or less each night had a greater accumulation of belly fat over the next five years, versus those who averaged six or seven hours.
Those who logged eight hours or more in bed each night also showed a bigger fat gain — but it was less substantial than that seen in “short sleepers.”
The study does not prove that too little or too much sleep directly leads to excess fat gain. But the findings support and extend those of other studies linking sleep duration — particularly a lack of sleep — to weight gain and even to higher risks of diabetes and heart disease.
As for why sleep duration might affect abdominal-fat gain, there are several theories.
There may be indirect effects; people who get too little sleep may be too tired during the day to exercise, while those who spend a lot of time in bed may spend less time being active, relative to people who sleep fewer hours.
Research also suggests that sleep loss alters people’s levels of appetite-regulating hormones — which could, in theory, spur them to overeat.
Depression, which often affects people’s sleep and has been linked to weight gain, could also be a factor.
[Source]
Chapter: Health :: 23 May 2010
