In-Lab Study Links Sleep Deprivation to Weight Gain

Larry Hand

July 02, 2013

Restricting sleep to 4 hours a night for 5 consecutive nights led to more weight gain for sleep-restricted participants than for control participants, according to results from a large, diverse, in-laboratory assessing sleep's effect on weight, calorie intake, and meal timing. The study was published in the July issue of Sleep.

Doctoral candidate Andrea M. Spaeth, MA, from the Department of Psychology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, and colleagues conducted a study involving 225 healthy adults aged 22 to 50 years at the Sleep and Chronobiology Laboratory at the Hospital of the University of Pennsylvania. Study participants were all nonsmokers whose body mass index (BMI) ranged from 19 to 30 kg/m2 and who did not experience any irregular sleep/wake routines during the 60 days before the study.

Researchers monitored the participants for a week at home before the laboratory phase, during which they studied the participants for 12, 14, or 18 consecutive days. They randomly assigned participants to either sleep restriction (SR; n = 198) or control (n = 27). SR participants were 45% women and 59% black, with a mean age of 31.3 years and a mean BMI of 24.8 kg/m2. Control participants were 44% women and 63% black, with mean age of 31.9 years and a mean BMI of 25 kg/m2.

SR participants had 2 initial nights of 10 to 12 hours in bed, followed by 5 consecutive nights of 4 hours in bed (from 4 am to 8 am). Control participants had 10 hours in bed (from 10 pm to 8 am). During the laboratory phase, participants could not leave the laboratory and could not exercise but were permitted to watch television, read, play video or board games, and do other sedentary activities while not sleeping or during testing while sitting at a computer.

The researchers monitored calorie intake in a subset of participants (31 SR and 6 control participants). They also measured and weighed all food provided during protocol-specified meal times. However, participants were allowed to eat whenever they wanted if it did not interfere with testing. Monitors recorded all food and drink consumed and left over. They measured body weights 6 to 7 days before the laboratory phase, on admittance, and on discharge.

SR participants gained significantly more weight (0.97 ± 1.43 kg) than control participants (0.11 ± 1.85 kg), possibly because of late-night eating and eating meals with higher fat content, the researchers write. SR participants whose caloric intake was monitored gained 0.52 ± 1.60 kg compared with control participants, who lost 0.53 ± 1.16 kg.

In addition, among SR participants, men gained more than women (P = .004) and blacks gained more than whites (P = .003).

"Although previous epidemiological studies have suggested an association between short sleep duration and weight gain/obesity, we were surprised to observe significant weight gain during an in-laboratory study," Spaeth said in a news release.

"African Americans, who are at greater risk for obesity and more likely to be habitual short sleepers, may be more susceptible to weight gain in response to sleep restriction. Future studies should focus on identifying the behavioral and physiological mechanisms underlying this increased vulnerability."

One coauthor has received funding for serving as a consultant, as a National Institutes of Health section member, and for lecturing and is an associate editor of Sleep. One coauthor is compensated by the Associated Professional Sleep Societies for serving as editor-in-chief of Sleep. Spaeth has disclosed no relevant financial relationships.

Sleep. 2013;36:981-990. Abstract

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