Behavioral and neuroendocrine characteristics of the night-eating syndrome.

CONTEXT: Investigators first described the night-eating syndrome (NES), which consists of morning anorexia, evening hyperphagia, and insomnia, in 1955, but, to our knowledge, this syndrome has never been subjected to careful clinical study.

OBJECTIVE: To characterize NES on the basis of behavioral characteristics and neuroendocrine data.

DESIGN AND SETTING: A behavioral observational study was conducted between January 1996 and June 1997 in a weight and eating disorders program at the University of Pennsylvania. A neuroendocrine study was conducted from May through August 1997 at the Clinical Research Center of the University Hospital, Tromso, Norway.

SUBJECTS: The behavioral study included 10 obese subjects who met criteria for NES and 10 matched control subjects. The neuroendocrine study included 12 night eaters and 21 control subjects. Behavioral study subjects were observed for 1 week on an outpatient basis, and neuroendocrine study subjects were observed during a 24-hour period in the hospital.

MAIN OUTCOME MEASURES: The behavioral study measured timing of energy intake, mood level, and sleep disturbances. The neuroendocrine study measured circadian levels of plasma melatonin, leptin, and cortisol.

RESULTS: In the behavioral study, compared with control subjects, night eaters had more eating episodes in the 24 hours (mean [SD], 9.3 [0.6] vs 4.2 [0.2]; P<.001) and consumed significantly more of their daily energy intake at night than did control subjects (56% vs 15%; P<.001). They averaged 3.6 (0.9) awakenings per night compared with 0.3 (0.3) by controls (P<.001). In night eaters, 52% of these awakenings were associated with food intake, with a mean intake per ingestion of 1134 (1197) kJ. None of the controls ate during their awakenings. In the neuroendocrine study, compared with control subjects, night eaters had attenuation of the nocturnal rise in plasma melatonin and leptin levels (P<.001 for both) and higher circadian levels of plasma cortisol (P = .001).

CONCLUSION: A coherent pattern of behavioral and neuroendocrine characteristics was found in subjects with NES.