There seems to be a decrease in the levels of melatonin (a hormone) at night in people who suffer from cluster migraines. A small study published in the journal Cephalgia (1996;16:494-496) looked at 20 patients with cluster headaches. This was a double-blind, placebo-controlled study. One group of ten subjects received 10 mg. of melatonin orally per day for two weeks. The ten subjects in the control group did not receive melatonin. Half of the subjects in the group receiving the melatonin had a reduction in the frequency of their headaches within five days of taking the supplement. The headaches stopped until the melatonin was discontinued. None of the subjects in the control group experienced relief.

In another study appearing in Neurology (August 2004;63(2 of 2):757), 32 subjects suffering from migraine headaches (out of 34 who started the study) were given 3 mg. of melatonin at night. Twenty-five of the 32 subjects had at least a 50% decrease in the incidence of headaches, with eight of the patients having complete remission.