Darkness May Spur Binge Eating in Dieters

Medically Reviewed by Gary D. Vogin, MD
From the WebMD Archives

Feb. 5, 2002 -- Winter's short days and overcast skies are known to trigger depression in some people. Now, researchers say that those dark, gloomy days can make some people more susceptible to binge eating.

In fact, people with the eating disorder bulimia often binge under cover of darkness, says author Joseph Kasof, a psychology and social behavior researcher at the University of California, Irvine. His study was published in the January issue of Personality and Individual Differences.

His findings may provide clues to preventing and treating eating disorders, he adds.

"Darkness provides a high-risk environment for binge-eating for certain people," Kasof says in a press release. "People who spend more waking hours in darkness may be more susceptible, especially if they feel a strong need to diet. But people who prefer to eat in a darkened room may find they lose their inhibitions."

Binge eating is not always a true eating disorder, says Kasof. However, eating massive amounts of food -- followed by purging, excessive exercise, and/or inappropriate use of laxatives -- is the pattern of bulimia.

Bulimia afflicts up to 10 million adolescent and college-age women and about one million men.

Typically, this pattern is triggered by an unrealistic perception of being overweight, he explains.

Psychotherapy helps most people overcome bulimic behaviors, he adds.

Kasof's studies involved more than 400 UCLA college students. Each completed a variety of questionnaires asking about their lighting preferences while eating and their dieting habits.

He found that among people who were not dieting, lighting conditions did not affect eating patterns; they were not prone to bulimia. However, those who did show symptoms of bulimia preferred eating in dimmer light, whether it was at night or not.

Other studies have looked at these issues, finding that bulimic behavior is more prevalent among "night people" who generally go to bed and wake up later, and thus spend more of their waking lives at night.

Evenings generally present the biggest challenge for dieters, says Kasof. They are more relaxed, often home alone watching TV -- factors that increase the risk of binging.

Cover of darkness helps diminish self-awareness, so any tendency to control eating goes out the window. It's the same reason why people prefer dimmer light when they expose their bodies -- when having sex, showering, dressing, he explains.

The type of depression called Seasonal Affective Disorder is caused by decreased sunshine exposure during short winter days, which lowers the amount of melatonin in the blood.

This doesn't seem to be what's going on here, Kasof says, because only dieters were affected by darkness in this study.

Frequent bingers may binge in dimmer light because it provides greater anonymity, because darkness lessens the guilt.

Dieters "may find that binging is more 'acceptable' in the dark," writes Kasof.