MELATONIN RHYTHMS IN WOMEN WITH ANOREXIA-NERVOSA AND BULIMIA-NERVOSA

To discern whether the multiple neuroendocrine-metabolic dysfunctions observed in women with anorexia nervosa (AN) and bulimia nervosa (BN) are associated with altered diurnal variations in serum melatonin prof iles, we compared cycling and amenorrheic women with normal weight BN (n = 8) and AN (n = 7) to 21 normal cycling controls. Endogenous depre ssion, which has confounded prior studies of melatonin profiles in wom en with eating disorders, was excluded in all subjects. Serum samples for melatonin measurements were obtained at frequent intervals (every 20 min) in a controlled light-dark environment, and cycling women were studied in the early follicular phase of the menstrual cycle. Mean (/-SE) peak melatonin levels were similar in AN, BN, and controls (325 +/- 43, 310 +/- 33, and 334 +/- 30 pmol/L, respectively). The time of melatonin peak, the time of onset and offset of the nocturnal serum me latonin excursion, and the duration of the nocturnal elevation were al so similar in the three groups. Analysis of covariance revealed no ind ependent effects of age or time of year on the data. Moreover, when su bjects were separated into those with and without menstrual cyclicity, no significant differences in any parameter of melatonin diurnal vari ation were observed. Taken together, these data suggest that pineal me latonin secretion is unaltered in women with eating disorders, in whom depression is excluded, and that the frequent occurrence of amenorrhe a in this population is not mediated by melatonin.