Sleep and Obesity

 Continued sleep loss appears to be associated with obesity according to recent studies, researchers have found that body mass increases as sleep time decreases. Loss of sleep leads to higher levels of the hormone ghrelin which triggers appetite. One study found that:" people who sleep two to four hours a night were 73 percent more likely to be obese than normal sleepers".

Subjects in one study who had their sleep time reduced to four hours a night for two consecutive nights were found to have: " an 18 percent decrease in leptin a hormone that tells the brain there is no need for more food, and a 28 percent increase in ghrelin, a hormone that triggers hunger".

American adults have reduced their sleep time by as much as two hours per night because of increasing pressures of modern living,this fact combined with a readily available food supply has been offered by some researchers as a possible reason for the rising rates of obesity.

Another study by Dr Shahrad Taheri from Bristol University found that:" People who habitually slept for 5 hours were found to have 15% more ghrelin than those who slept for 8 hours. They were also found to have 15% less leptin. These hormonal changes may cause increased feelings of hunger, leading to foraging in the fridge for food".

A study by Van Cauter and colleagues found that subjects who had only four hours of sleep had their ghrelin to leptin ratios increased by 71 percent.They found that : " as hunger increased, food choices changed. After two nights of curtailed sleep subjects found foods such as candy, cookies and cake far more appealing. Desire for fruit, vegetables or dairy products increased much less".

Although studies have found a correlation between reduced sleep time and obesity, the connection has yet to be proved, for other factors may be involved in the increased and widespread incidence of obesity.

References:

 Taheri S, Lin L, Austin D, Young T, Mignot E (2004) Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. PLoS Med 1(3): e62

Spiegel K, Leproult R, Van Cauter E (1999) Impact of sleep debt on metabolic and endocrine function. Lancet 354: 1435–1439

SOURCES: North American Society for the Study of Obesity's Annual Scientific Meeting, Las Vegas, Nov. 14-18, 2004. WebMD Medical News: "Sleep More and You May Control Eating More." WebMD Medical News: "Why Dieting Makes You Hungrier." News release, North American Society for the Study of Obesity