Excessive daytime sleepiness associated with insufficient sleep.

Chronic insufficient sleep as an identifiable cause of excessive daytime sleepiness was investigated post hoc by comparing a series of patients with this diagnosis with patients with narcolepsy. Among the prominent features differentiating patients with insufficient sleep from patients with narcolepsy was the report, obtained on the sleep history, of a disparity between the reported amount of sleep obtained on weekdays versus weekends. On evaluation in the laboratory, patients with insufficient sleep showed atypically high sleep efficiency at night and a prolonged sleep time (longer than they report sleeping on a weekday night at home). Compared with patients with narcolepsy, they show a somewhat elevated percentage of stage 3-4 and REM sleep, although this is probably not higher than that of age-matched controls. On the Multiple Sleep Latency Test they displayed moderate sleepiness and no sleep onset REM periods. A mental status examination and Minnesota Multiphasic Personality Inventory did not suggest a primary psychiatric disorder.