Depression and endogenous melatonin in postmenopausal women

Background: Previous reports on melatonin secretion in depression are numerous but conflicting. There are very few studies relating the duration of the nocturnal melatonin peak to depression, and the results of those studies have been equivocal. Methods: We studied mood disorders and urinary melatonin excretion in 382 postmenopausal women. Psychiatric diagnoses and global assessment of functioning (GAF) scores were determined based on a Structured Clinical Interview for DSM-IV Axis I Disorders (SCID). Urinary 6-sulfatoxymelatonin (6-SMT) samples were collected for two 24-h periods at home. Results: A positive family history of depression was significantly related to a longer duration of 6-SMT excretion. There were marginally significant associations between current major depression and delayed offset of 6-SMT excretion and between later acrophase and lifetime major depression, even with control for age, ethnicity, season, and several medications. Limitations: The subjects were studied in their home environments, where light effects were not controlled. Data were restricted to postmenopausal women, including a limited number of subjects with current major depression. Conclusions: These results suggest that there might be a familial vulnerability in the endogenous melatonin signal in subjects prone to depression, and an abnormality in the duration of the melatonin signal in those with current major depression.