Daytime performance deficits and physiological vigilance in untreated patients with narcolepsy-cataplexy compared to controls.

Ten patients, 7 female, 3 male, aged 17-65 years (mean 40) with narcolepsy-cataplexy were compared off treatment to matched controls on 4 performance tests. The tests were the 1 h Wilkinson auditory vigilance task, and 3 shorter tests including the 4-choice serial reaction time, the paced auditory serial addition task (PASAT) and digit span. Tests were counterbalanced and polygraphic recordings were done during all but the 4-choice serial RT. Subjective sleepiness was assessed by the 1-7 levels of the Stanford Sleepiness Scale and effort in the tests by a similar 1-7 scale. Practice sessions were held. Narcoleptics showed poorer performance on the more monotonous tests of auditory vigilance (fewer hits) and the 4-choice serial RT (longer reaction times, more 'gaps'). There were no significant differences between groups on the other performance tests. Narcoleptics were subjectively sleepier during all tests and over-all. But there was no good correlation between perceived degree of sleepiness and performance. They also expressed greater effort to perform the PASAT. The narcoleptics showed greater amounts of drowsiness and light sleep only during the 1 h vigilance test. For the detections of those signals (shorter times) occurring after 13 sec or more of polygraphic wakefulness, narcoleptics performed as well as controls.