Light Therapy Lessens Bulimics' Binging and Purging
Rosenthal is clinical professor of psychiatry at Georgetown University School of Medicine in Washington, D.C., and author of the book Winter Blues.
He suggests that in bulimic patients, the purging that follows binge eating is not merely a frantic effort to lose the weight one has gained, but may be indulged in because it makes the bulimic feel good. And he believes that light affects the brain in such a way as to both diminish the need for food and to dampen the need for the good feelings that come with purging.
Rosenthal also says that light increases brain levels of serotonin, a chemical involved in mood that also regulates the sense of "satiety" -- the feeling of being full after eating. Thus, it may counteract the feeling that bulimic patients report of never being "full enough," he says.
"If light therapy boosts serotonin, that could easily explain how the brain is letting the person know that the patient is full," Rosenthal says.
As if to bring things full circle, some evidence -- not fully explored by researchers -- suggests that people eat more in the winter months and that patients with eating disorders experience a worsening of symptoms.
"That ties together the effect of light on both seasonal affective disorder and eating disorders," Rosenthal says.