Alerting effects of naps in patients with narcolepsy.

As part of their standard diagnostic evaluation, 45 patients with narcolepsy and 45 patients with other disorders of excessive sleepiness (DOES), primarily obstructive sleep apnea, each underwent one of three nap conditions that involved manipulating time in bed on the 1600 h latency test of the standard multiple sleep latency test (MSLT) and varying the time between the 1600-h latency test and a subsequent fifth latency test. Compared with the mean of tests 1-4, a 15-min nap at 1600 h (condition 1) increased latency to stage 1 sleep on a latency test 15 min later in both groups. However, the increase was greater for patients with narcolepsy than with other DOES. A 30-min nap at 1600 h (condition 2) produced increased latency 15 min later, but the increase was greater for patients with other DOES. While narcoleptic patients showed no change in latency as a function of increased nap duration, the other DOES patients had increased latencies. When tested 30 min after a 15-min nap (condition 3), narcoleptic patients had latencies that did not differ from those of tests 1-4, while the other DOES patients sustained their increased latencies.