Kyle P. De Young

Objective Circadian rhythm disruptions are associated with binge eating, can be causal of negative mood, and may be corrected with bright light exposure. A subtype of individuals with binge‐spectrum eating disorders are characterized by combined high dietary restraint and negative affect. These individuals have higher eating disorder psychopathology and poorer treatment response. We aimed to test the targeted effects of morning bright light exposure on individuals with binge‐spectrum eating disorders, hypothesizing significant reductions in binge eating for those characterized by high dietary restraint and negative affect. Methods Participants ( N = 34 females with binge‐eating disorder and bulimia nervosa) used a morning bright light and normal light for 10 consecutive days each, in randomized order. They completed the Change in Eating Disorder Symptoms (CHEDS) scale at baseline, day 12 (when they switched lamps), and day 22. We conducted moderation analyses, clustering data by person, controlling for order, and examining the effect of light condition on binge eating according to baseline restraint and negative affect. Results At high levels of combined dietary restraint and negative affect, participants experienced a reduction in binge eating and food preoccupation following exposure to morning bright light. There were no changes in restrictive eating, body preoccupation, body dissatisfaction, or body checking following exposure to morning bright light for these individuals. Discussion These findings suggest that morning bright light may be a useful adjunct to empirically supported eating disorder treatments that target binge eating, especially for individuals characterized by the difficult to treat restraint/negative affect subtype. Public Significance At high levels of combined dietary restraint and negative affect, participants with binge‐spectrum eating disorders experienced a reduction in binge eating and food preoccupation following exposure to morning bright light. These findings suggest that morning bright light may be a useful adjunct to empirically supported eating disorder treatments that target binge eating, especially for individuals characterized by the difficult‐to‐treat restraint/negative affect subtype.

Caloric consumption occurs in rhythms, typically during daytime, waking hours, marked by peaks at mealtimes. These rhythms are disrupted in individuals with eating disorders; mealtime peaks are blunted and delayed relative to sleep/waketimes. Individuals with eating disorders also tend to experience an overall phase delay in appetite; they lack hunger earlier in the day and experience atypically high hunger later in the day, the latter of which may culminate in binge‐eating episodes. This disruptive appetitive behavior—early in the day restrictive eating and later in the day binge eating—may be partially accounted for by circadian disruptions, which play a role in coordinating appetitive rhythms. Moreover, restrictive eating and binge eating themselves may further disrupt circadian synchronization, as meal timing serves as one of many external signals to the central circadian pacemaker. Here, we introduce the biobehavioral circadian model of restrictive eating and binge eating, which posits a central role for circadian disruption in the development and maintenance of restrictive eating and binge eating, highlighting modifiable pathways unacknowledged in existing explanatory models. Evidence supporting this model would implicate the need for biobehavioral circadian regulation interventions to augment existing eating disorder treatments for individuals experiencing circadian rhythm disruption. Public Significance Existing treatments for eating disorders that involve binge eating and restrictive eating mandate a regular pattern of eating; this is largely responsible for early behavioral change. This intervention may work partly by regulating circadian rhythm and diurnal appetitive disruptions. Supplementing existing treatments with additional elements specifically designed to regulate circadian rhythm and diurnal appetitive rhythms may increase the effectiveness of treatments, which presently do not benefit all who receive them.