Night eating syndrome in patients with eating disorders: Is night eating syndrome distinct from bulimia nervosa?

Background/Purpose: Night eating syndrome (NES) is a diagnosis newly introduced in the fifth version of the Diagnostic and Statistical Manual of Mental Disorders. This study investigated the characteristics of NES in individuals with eating disorders and the clinical significance of NES in individuals with bulimia nervosa (BN). Methods: We recruited participants with eating problems at psychiatric outpatient clinics and from Internet referrals and age, sex, and educational level-comparable controls from September 2013 to April 2017. All participants received in-face structured clinical interviews to establish their eating disorder and NES diagnoses and completed questionnaires assessing NES, eating attitudes/behaviors, depression, sleep disturbances, morningness/eveningness preference, and functional impairment. Comparisons of measurements were made across patients with eating disorder subtypes and across patients with NES-only, BN-only, comorbid BN and NES, and controls. Results: NES was identified in 10.3%, 34.9%, and 51.7% of the individuals with anorexia nervosa, BN, and binge-eating disorder, respectively. NES-only group had more frequent binge-eating, higher degrees of eating pathology, depression, sleep disturbances, and functional impairment compared to controls; however, NES-only group shared similar levels of disordered eating, depression, sleep disturbances, and functional impairment with BN-only group. BN-NES group had no difference from BN-only group on most eating pathology, psychopathology, and functional impairment, except for the presence of greater eating and weight concerns. Conclusion: NES has its clinical significance; however, it overlaps with BN in several dimensions of psychopathology. Presence of night eating in a BN group may not contribute clinically meaningful psychopathology.