Night Eating Syndrome
ALBERT J. STUNKARD
Recent years have seen a renewal of interest in the relationship between eating disorders and obesity. Such an interest goes back a long way, to a time when all obesity was believed to be due to an eating disorder. People became obese by eating too much, the argument went: What better evidence was there that their eating was disordered? This simplistic view is no longer held and, as a result, for some time little attention was paid to the possibility that disturbed eating might contribute to obesity. This situation is changing, and two eating disorders have now been linked to obesity. The first is binge eating disorder (see Chapter 31), and the second is the night eating syndrome.
The night eating syndrome was first described by the author in 1955 as a disorder comprising the triad of morning anorexia, evening or nocturnal hyperphagia (in full consciousness), and insomnia. Clinical investigation revealed that it occurred (1) disproportionately among obese persons, (2) during periods of life stress, and (3) responded to alleviation of the stress. The night eating syndrome appeared to be a special circadian stress response characteristic of some obese persons.
Studies using the above criteria estimate that the prevalence of the night eating syndrome in the general population is approximately 1.5% and that prevalence increases with increasing weight, from about 10% of persons enrolling in obesity clinics to as high as 25% of patients undergoing surgical treatment for obesity. Among persons identifying themselves as binge eaters, binge eating disorder (see Chapter 31) is somewhat more prevalent (20%) than the night eating syndrome (15%). It occurs among about 5% of those presenting for the treatment of insomnia (although other sleep-related eating disturbances are also seen in which patients are either partially or totally unconscious).
Much of what we know about the night eating syndrome is derived from a study by Birketvedt and colleagues. It revealed that the food intake of obese night eaters was some-