Hypersomnia and the perception of sleep-wake states: some preliminary findings.

35 hypersomniacs (20 with obstructive sleep apnea and 15 with narcolepsy) and 15 controls estimated sleep latency during systematic trials of attempting to remain awake during the day. The error in subjective assessment of sleep latency was more variable for both patient groups than for controls. In addition, narcoleptics could not provide a determination of sleep latency or differentiate sleep-wake states on nearly 23% of all trials. Ratings on a subjective sleepiness scale did not covary with objective sleep latency for any hypersomniac. The findings suggested that patients with either sleep apnea or narcolepsy had difficulty differentiating sleep and quiet wakefulness during the day.