Effect of fluoxetine on melatonin in patients with seasonal affective disorder and matched controls.

Abstract

The aim was to investigate the secretion profile of melatonin and seasonal affective disorder before and after treatment with fluoxetine. 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. Fluoxetine significantly reduced melatonin levels in both groups. There was no significant difference in melatonin secretion between the groups. The effect of fluoxetine differs from tricyclics and fluvoxamine, both of which increase melatonin.