Supersensitivity to melatonin suppression by light in young people at high risk for affective disorder. A preliminary report.

Affective illness aggregates in families and appears to be heritable. Bipolar affective patients have been found to be supersensitive to the suppressive effect of light on the nocturnal secretion of melatonin, both in ill and well states. We tested young people aged 15 to 25 years with one manic-depressive parent (n = 18), major affective disorder on both sides of the family (n = 7), and age-matched controls (n = 20). The subjects in the high-risk groups were more likely to show supersensitivity in melatonin response to light at night than controls. Follow-up studies are necessary to assess the predictive value of this response.