Nocturnal sleep recording with cassette EEG in chronic headaches. Many headache patients complain of poor sleep, and sleep disturbance has been shown to play a role in chronic pain. We recorded nocturnal sleep with a 4-channel cassette EEG monitoring device in 10 common migraine patients, 10 individuals with muscle contraction (tension) headache, and 10 chronic tension-vascular headache sufferers. Migraine patients had essentially normal sleep, although rapid eye movement (REM) sleep and REM latency were increased. Patients with tension headache had reduced sleep time and sleep efficiency, decreased sleep latency but frequent awakenings, increased nocturnal movements, and marked reduction in slow wave sleep, without change in REM sleep or latency. Mixed-element headaches with both tension and vascular features were associated with reduced sleep, increased awakening, diminished slow wave sleep, and REM sleep that was decreased in amount and reduced in latency. The findings suggest that patients with intermittent migraine may have minimal sleep disturbance, while chronic headache may be worsened by chronically poor sleep. Muscle contraction headache may be associated with frequent awakenings and decreased slow wave sleep similar to the sleep changes of fibrositis, while chronic tension-vascular headache may have a depressive substrate. Four-channel sleep recording may miss contributory sleep apnea, but nonetheless cassette EEG may facilitate outpatient evaluation of refractory headaches. 