Background: The aim was to investigate the secretion profile of melatonin and seasonal affective disorder before and after treatment with fluoxetine.
Method: A six-week case-controlled study with repeated overnight blood sampling was conducted. Ten patients fulfilling the criteria for major depressive disorder, seasonal type, with a 29-item Hamilton Depression Rating Scale (HDRS) score of at least 20 were compared with ten age- and sex-matched healthy controls in a clinical laboratory. The effects of fluoxetine (20 mg/day) on the HDRS and melatonin concentration were measured.
Results: Fluoxetine significantly reduced melatonin levels in both groups. There was no significant difference in melatonin secretion between the groups.
Conclusions: The effect of fluoxetine differs from tricyclics and fluvoxamine, both of which increase melatonin.