An hour more sleep reduces fat percentage by three percent

Your fat percentage decreases by 2.8 percent for each hour a day more sleep you get, researchers at the University of Bristol calculated. The researchers used data from thirty healthy Greek women between 30 and 60 years of age.

The figure below shows the researchers’ results. Each dot represents the fat percentage of one woman, and the number of hours sleep that the woman gets per day.


The researchers speculate that little sleep leads to an increase in the production of a hormone that stimulates appetite such as ghrelin, and at the same time decreases the production of a appetite-suppressing hormone such as leptin. They didn’t find a relationship between sleep and appetite, however. According to the researchers, this was because the group of women they used was too small.

Association between nocturnal sleep duration, body fatness, and dietary intake in Greek women.


We investigated the association of nocturnal sleep duration with body fatness, energy, and macronutrient intake in female adults.

Thirty healthy Greek women 30-60 y of age and under no medication were recruited for an observational, cross-sectional study in Athens, Greece, in 2005. Participants’ height, weight, skinfold thickness, and waist and hip circumferences were measured. All subjects completed a Sleep Habits Questionnaire and a 7-d sleep diary to estimate nocturnal sleep duration. Two 24-h dietary recall interviews were conducted to assess dietary intake.

Nocturnal sleep duration was negatively associated with body fatness (r = -0.614, P < 0.001) and body mass index (r = -0.401, P < 0.05). Each 1-h decrease in nocturnal sleep duration was associated with a significant increase in body fat of 2.8% (95% confidence interval -4.6 to -1.0) when the effects of age and energy intake were held constant. A weak positive association between sleep duration and saturated fat was observed (r = 0.392, P < 0.05). However, no significant association of sleep duration with certain central obesity indices, energy intake, or a preference for fat or carbohydrate consumption was found. CONCLUSION: The present study identifies an independent negative association of nocturnal sleep duration with body fatness. Therefore, the shorter the sleep duration, the greater is the body fatness. The hypothesis that sleep duration is associated with energy intake and a preference for fat or carbohydrate consumption was not supported. PMID: 17884345 [PubMed - indexed for MEDLINE] Source: