Plasma concentrations of melatonin in panic disorder.

Nocturnal plasma melatonin concentrations were measured in seven patients with panic disorder and eight healthy control subjects. The five patients who had never received psychotropic medication had significantly greater melatonin concentrations from 4:00 a.m. to 7:00 a.m. than the control subjects. In addition it is possible that a phase delay occurred in these unmedicated patients. The findings are discussed in terms of previous studies showing increased melatonin in manic patients and the effect of intense stress on melatonin synthesis. The two patients who had been medication free for only 1 week showed a decreased melatonin rhythm, which is consistent with previous findings in medicated patients.