Melatonin secretion in SAD patients and healthy subjects matched with respect to age and sex.

Among the competing hypotheses concerning the aetiology of SAD is the melatonin hypothesis, which is the target of this study. 5 test subjects with SPAQ seasonality score (SS) > or = 9 and 5 controls with SS 3/4 4 participated in the study. The participants took saliva samples at home. Samples were collected 4 times a day for 3 days in March, 1999. Melatonin concentrations were determined by RIA. No significant differences in circadian rhythms were found between the groups; i.e. the curves for both groups ran parallel. However the concentrations of melatonin in the SAD patients were found to be on average 2.4 times as high as in the control group; the difference is significant at p<0.001. Our results support the melatonin hypothesis.