It looks like catching only a few hours of sleep contributes to weight gain because burning the midnight oil is often accompanied by snacking. The finding appears online today in Sleep, the journal published by the Associated Professional Sleep Societies.
Researchers recruited 225 healthy adults aged 22 to 50 years who were placed in the Sleep and Chronobiology Laboratory at the Hospital of the University of Pennsylvania for up to 18 consecutive days. The participants were served meals at scheduled times but were permitted to eat additional food from the laboratory kitchen at any time of the day. Participants were allowed to move around but not to exercise. Watching television, reading, playing video games, or performing other sedentary activities was permitted.
Sleep-restricted participants, who spent only 4 hours in bed from 4 AM to 8 AM for 5 consecutive nights, gained more weight (about 2 pounds) than control participants (about a quarter of a pound), who were in bed for 10 hours daily from 10 PM to 8 AM. This additional weight gain was due to an overall increase in the number of calories consumed throughout the day and extra meals eaten during the late-night period of additional wakefulness. Also, the proportion of calories consumed from fat was higher during late-night hours than at other times of the day.
In addition, the researchers found that among the sleep-restricted participants, men gained more weight than women and blacks gained more than whites.
The study adds to the growing body of evidence suggesting a link between sleep patterns and weight. Other research has explored possible behavioral and physiological mechanisms affecting the relationship between sleep duration and weight gain. For example, sleep restriction is associated with increased craving for foods high in carbohydrates, greater consumption of calories from carbohydrates or fats, and increased caloric intake from snacks.
The 2004-2007 National Health Interview Survey found that almost 30% of adults report sleeping 6 hours or less every night.