Context: Night eating syndrome (NES) is characterized by evening hyperphagia and frequent awakenings with ingestion of food. It is associated with obesity and depressed mood. Greater understanding of hormonal influences on NES is desirable.

Objective: Our objective was to evaluate 25-h profiles of hormones involved in energy balance, sleep, and stress in NES.

Design: Blood assays for glucose, insulin, ghrelin, leptin, melatonin, cortisol, TSH, and prolactin were sampled repeatedly among NES and control subjects. Food intake and depressive symptoms were assessed.

Setting and participants: Fifteen NES and 14 matched control participants stayed three nights in a General Clinical Research Center.

Main outcome measures: We assessed differences between NES and control participants in the 25-h profiles of eight hormones.

Results: Nocturnal food intake was higher among NES participants, although their daily calorie intake was similar to that of controls. Reflecting their increased nocturnal intake, insulin (P < 0.001) and glucose levels (P = 0.07) among NES participants were higher than those of controls. Ghrelin levels were significantly lower in NES participants than in controls from 0100-0900 h (P = 0.003). Levels of plasma cortisol, melatonin, leptin, and prolactin did not differ between groups, but there was a trend for TSH levels (P = 0.07) to be higher during the 25 h in NES. NES participants had greater depressive symptoms than controls (P < 0.001). The differences in the levels of glucose, insulin, and ghrelin between NES and controls are closely associated with nocturnal food intake.