In major depression, biological rhythm disturbances in sleep, appetite, and mood suggest dysregulation in neuroendocrine functions, possibly in the pineal gland. In this study, pineal gland function was examined by measuring nocturnal serum melatonin levels during both wakefulness and sleep in depressed children and adolescents.
Twenty-two youths aged 8 to 17 years primarily with major depression were compared with 19 controls. Blood samples were drawn every half hour from 6 PM to 7 AM. Nocturnal serum melatonin levels were measured by radioimmunoassay.
The overall nocturnal serum melatonin profile from 6 PM to 7 AM was significantly higher (mean±SD, 0.18±0.14nmol/L) in the depressed group than in the controls [mean±SD, 0.15±0.10 nmol/L, F(1,26)=4.37, P<.05]. In dim light, when the subjects were awake, no difference existed between the 2 groups. After lights-out, from 10 PM to 7 AM, the melatonin profile rose in both groups; however, the depressed group had a significantly higher increase (mean±SD,0.24±0.14nmol/L) than the controls [mean±SD,0.18±0.07nmol/L, F(1,26)=4.93, mean square error=0.11, P=.04]. Post hoc analysis showed a significantly higher melatonin profile in depressed subjects without psychosis (n=15) than in depressed subjects with psychosis (n=7) or in the controls.
Measuring the overall nocturnal serum melatonin profile during darkness may help to differentiate children and adolescents with major depression without psychosis from those with psychosis and from controls.