The alerting effects of short and long naps in narcoleptic, sleep-deprived, and alert individuals

Eleven narcoleptic patients and 22 age- and gender-matched normal controls participated in a study to determine the alerting effects of differing nap lengths. All narcoleptic patients had been previously diagnosed [mean sleep latency on the multiple sleep latency test (MSLT) less than or equal to 5 minutes with two or more sleep-onset rapid eye movement periods (SOREMPs)]. Healthy, normal subjects with a mean sleep latency on the screening MSLT greater than or equal to 8 minutes were randomly assigned to one of two groups (i.e. sleep-deprived and alert). All subjects completed two experimental night and days with at least 5 days between sessions. On the evening prior to each experimental day, narcoleptic and alert subjects spent 8 hours in bed and sleep-deprived subjects spent 0 hours in bed. The following day, all subjects underwent one of two napping conditions, 15 or 120 minutes in bed. Both naps were terminated at noon. Every subject underwent both conditions and the order of conditions was counterbalanced. From 1215 to 1355 hours all subjects underwent a modified MSLT At 1500 hours, the subjects had a I-hour nap. The results showed that the 120-minute nap condition was more beneficial than the 15-minute nap. Narcoleptic and sleep-deprived subjects were shown to have comparable levels of sleepiness on the modified MSLT. However, a differential response pattern on their latency to sleep was noted on the I-hour nap. Sleep-deprived subjects were shown to be differentially more alert following a 120-minute nap opportunity. In contrast, for narcoleptic patients the beneficial effects of the nap were lost when tested 3 hours later. These results show that narcoleptic patients benefit from a longer nap but that these benefits are short-lived.