Polysomnographic, performance, and personality differences of sleepy and alert normals

The nocturnal sleep, performance, and personality of healthy, asymptomatic, normal young men, 18 who had unusually short sleep latencies on the Multiple Sleep Latency Test (average latency, less than or equal to 6 min) and 20 with unusually long latencies (average latency, greater than or equal to 16 min) were compared. On the nocturnal sleep recording, sleepy subjects had a shorter sleep latency, less waking time, and overall greater sleep efficiency than alert subjects. During the day, sleepy subjects performed more poorly than alert subjects on divided attention and vigilance performance tasks. The sleepy and alert subjects did not differ appreciably on the Minnesota Multiphasic Personality Inventory and Jenkins Activity measures of personality. On the Institute of Personality and Ability Testing Anxiety Scale, the sleepy subjects showed higher levels of anxiety than the alert subjects. The data were interpreted as indicating that the sleepy subjects had a sleep debt due to chronic sleep restriction.