Are sleep duration and body mass index (BMI) connected Researchers at Columbia University found a correlation. The results of their study were reported in Sleep (October 26, 2005). These researchers conducted a longitudinal analysis of data on >9500 participants in the 1982-1984, 1987, and 1992 Epidemiologic Follow-up Studies of the first National Health and Nutrition Examination Survey. Their findings showed that individuals aged 32 to 49 who slept <7 hours when initially interviewed had a higher BMI and were more likely to be obese, compared with participants who slept 7 hours. Yet, this finding was not seen in older participants.
In an editorial responding to the study, investigators reported on their evaluations of 13 other population and longitudinal studies conducted since 1992. Although a causal relationship between obesity and sleep has not been observed, genetic studies with animals and small-scale experiments using sleep restrictions with individuals suggested that sleep deprivation may be associated with obesity in 3 ways: (1) compromising the body's sensitivity to insulin; (2) increasing the growth hormone ghrelin that affects appetite and energy level; and (3) decreasing leptin.