Magnitude of the problem
Eating disorders are frequently assumed to be a modern disease whose origins lie in an overstressed, prosperous world. Anorexia nervosa appears to be uncommon outside Western society, but immigrants from less-developed to more-developed countries are more likely to develop eating disorders than their sisters who stayed in their countries of origin. Eating disorders are modern clinical concepts based on diagnostic criteria of relatively recent origin. Many persons struggling with eating disorders report disturbed sleep patterns and some report night-time eating as a problem. Problematic night-time eating may be due to sleep-related eating disorders with altered alertness, binge eating disorder and bulimia nervosa with night-time eating, dissociative states and the Kleine-Levin syndrome. The common theme in eating disorders is preoccupation with body weight and shape, often accompanied by dietary faddism with unusual food preferences. Hazardous weight-loss measures include self-induced vomiting, misuse of laxatives and diuretics, and excessive exercise.