The comparison of 24 hours polysomnographic recordings of middle-aged narcoleptic subjects (39-51 years, group A) with 11 twenty four hours and 3 nighttime recordings of elderly narcoleptic subjects (aged 60-72 years, group B) using T test for non paired values was made. No difference was found in parameters of nighttime registrations: total sleep time (A:510.4 +/- 71.2 min., B: 475.9 +/- 92.4 min), intrasleep wakefulness (A: 107.5 +/- 75.3 min., B: 112.3 +/- 65.3 min), latencies of sleep stages (1NREM-A: 3.4 +/- 2.8 min, B: 4.3 +/- 3.7 min, 2NREM-A: 7.4 +/- 7.6 min, B: 6.6 +/- 12.7 min, 3NREM-A: 27.2 +/- 10.4 min, B: 51.6 +/- 62.6 min, REM-A: 62.2 +/- 59.5 min, B: 64.6 +/- 71.6 min), relative duration of each sleep stage (1NREM-A: 20.0 +/- 9.5%, B: 21.4 +/- 13.2%, 2NREM-A: 51.3 +/- 8.5%, B: 51.9 +/- 14.2%, 3 +/- 4NREM-A: 8.2 +/- 6.5%, B: 7.2 +/- 6.5%, REM-A: 20.4 +/- 4.5%, B: 19.1 +/- 5.7%), and sleep continuity index (A: 0.83 +/- 0.11, B: 0.81 +/- 0.11). Total sleep time in the daytime was similar (A: 160.5 +/- 53.8 min, B: 180.5 +/- 59.9 min), the number of sleep episodes during the day was in elderly patients higher (A: 3.4 +/- 1.2, B: 4.8 +/- 1.3, P < 0.05) and the number of sleep onset REM periods was in elderly subjects slightly higher (A: 1.9 +/- 1.1, B: 2.7 +/- 1.7). The authors conclude that the nocturnal sleep of both age groups of narcoleptic subjects is disturbed and the character and the intensity of this disturbance are similar. Elderly narcoleptic subjects displayed more daytime sleep periods.