Reprinted from Eating Disorders Review
May/June 2010 Volume 21, Number 3
©2010 Gürze Books
As many as half of patients with eating disorders may have disturbed sleep. Sleep-related eating disorders have also recently been described as independent clinical syndromes (Birketvedt et al., 1999) [Note: also see the Q&A section in this issue].
Dr. Kyung Ran Kim and colleagues at Yonsei University College of Medicine, Seoul, Korea, interviewed 400 female outpatients diagnosed with anorexia nervosa (AN) or bulimia nervosa (BN) who sought treatment at the Mind & Mind Eating Disorder Clinic and Severance Mental Health Hospital in Seoul. About half (201) of the outpatients interviewed in the study reported having sleep disturbances (Psychiatry Res.2010; 176:88).
Although there were no significant differences in the prevalence of sleep disturbances between those with AN and BN, one dissimilarity did emerge. Patients who binge-ate or purged were more likely to have sleep disturbances than were patients who did not (56.8% versus 34.1%, respectively), regardless of the diagnosis. When the types of disturbances were differentiated, the most common problems were difficulty falling asleep (130 women) and mid-sleep awakening (71 women).
Eating disorder patients with sleep disturbances also had high subscale cores on the Eating Disorders Inventory-2 (EDI-2; Garner, 1991).Among the increased cores were body dissatisfaction, perfectionism, and asceticism; however, these symptoms, which might be more closely associated with restricting symptoms, were not significantly different in the two groups.
The authors proposed several theories about the high comorbidity of sleep disorders and eating disorders. First, emotions common to eating disorders, such as anger, depression, and irritability, may explain these subjective sleep complaints. Second, patients with sleep disturbances might be more prone to behavioral disturbances, such as binge-eating and purging. Third, disturbances in body and weight perception might emerge in the form of other somatic psychological complaints.
Are such disturbances useful clinical markers?
The authors also suggest that their study results show that sleep disturbances might be useful as clinical markers of eating disorders. Dr. Kim and colleagues point to a longitudinal study showing that sleep was particularly fragmented when patients were in the low-weight state but once they returned to normal weight, they slept longer and had fewer nighttime awakenings. Thus, in a way, changes in sleep disturbances might act as a secondary measure of recovery.