Sleep Problems May Prompt Weight Gain

Previously, a number of studies report that reduced sleep is linked to weight gain.  Ari Shechter, from St. Luke's-Roosevelt Hospital (New York, USA), and colleagues investigated the effects of sleep architecture on hunger to determine whether specific stages of sleep, rather than simple duration, would affect changes in appetite and food desires in healthy adults.  The investigators enrolled 27 healthy adults, ages 30 to 45 years, who underwent two six-day periods of laboratory observation—a "habitual sleep" phase, during which they were allowed nine hours to sleep, and a "short sleep" phase, during which they were allowed four hours to sleep. Each phase was separated by four weeks.  For the first four days in both phases, participants ate meals calibrated to meet their energy requirements for weight maintenance. On day four, participants were asked to rate their hunger and level of desire for different foods. Resting metabolic rate was measured in the fasted state on day five, and participants were then allowed to select their own foods for the final two days. The team observed that the short sleep condition resulted in reductions in the duration and percentage of stage 2 and REM sleep and increased the percentage of total sleep time spent in slow wave sleep. Some of these changes were related to decreased resting metabolic rate, increased feelings of hunger, and increased intake of calories, fat, and carbohydrate. The investigators observed a positive association between stage 2 sleep duration and resting metabolic rate, as well as an inverse relation between stage 2 sleep percentage and calories consumed.  Reduced percentage of sleep time spent in REM sleep, as well as slow wave sleep, was also associated with greater fat and carbohydrate intake.  Writing that: “This study demonstrates that changes in sleep architecture are associated with markers of positive energy balance and indicate a means by which exposure to short sleep duration and/or an altered sleep architecture profile may lead to excess weight gain over time,” the study authors submit that while sleep duration is important, the composition of sleep—the time and percentage of overall sleep spent in each stage— plays n important role in the relationship between sleep and obesity.