The nature of sleep attack and other symptoms of narcolepsy

Abstract

The electroencephalogram, electro-oculogram and electromyogram of the mental muscle were simultaneously recorded in eighteen narcoleptics and thirty controls under each of the following three conditions in the daytime, on different days: (I) lying on a bed: bed(1); (II) sitting on a stool, then, on a chair, and finally, lying on a bed: stool(2), chair(2) and bed(2); (III) sitting on a chair: chair(3). Recording in each posture was performed for about 50 min and 152 recordings, 81 in the narcoleptics and 71 in the controls, were obtained. Under every condition, the narcoleptics fell asleep with a shorter latency and spent in sleep a larger percentage of recording time than the controls, and sleep of the narcoleptics was deeper than that of the controls. Sleep of the narcoleptics was deeper and more stable under bed(1) and bed(2) than under chair(2) and chair(3), and the latter than under stool(2) condition. Similar relations were found in the controls. The REM stage of sleep occurred in variable number of narcoleptics with sleep attack and other main symptoms under different conditions. It occurred in fifteen of eighteen narcoleptics under bed(1), in eleven of eighteen narcoleptics under both chair(2) and bed(2), in five of nine narcoleptics under chair(3) and in only two of eighteen narcoleptics under stool(2) condition. Latency of the REM stage was 29 min and 34.5 min respectively under stool(2). Under the other conditions this stage occurred at the onset of, or soon after the onset of sleep in most cases. These and other findings would suggest that, during sleep under unstable and uncomfortable conditions, narcoleptics are completely or incompletely deprived of the REM stage, and that, during sleep in the following period under stable and comfortable conditions, they tend to show a compensatory increase in its amount. Cataplexy of brief duration occurred in one narcoleptic under chair(2). Sleep paralysis, hallucinations and/or dreams were experienced by twelve narcoleptics; under stool(2) by one, under chair(2) by four and under bed(2) by seven. All of the twelve patients showed the REM stage under these conditions. In conclusion, a marked tendency to fall asleep in narcoleptics brings about sleep attack, and another tendency to fall in the REM stage at the sleep onset brings about cataplexy, sleep paralysis and hypnagogic hallucinations.