Fig. 6

Symptoms of fatigue and the results of performance test (psychomotor vigilance task; PVT). a The data were classified according to the time of the test. Each column and bar indicate the mean and standard error; A immediately after rising (N = 128, for the subjective symptoms and the performance test), B approximately noon (N = 128 for the subjective symptoms, no performance test was administered at this time), C immediately before going to bed (N = 384 for the subjective symptoms; N = 256 for the performance test). b The data were classified according to the duration of the sleep period. Each number indicates the mean and standard error. I indicates the first 2 days with 8 h of sleep (N = 48 for subjective symptoms; N = 36 for the performance test), II the next 5 days with 5 h of sleep (N = 120 for subjective symptoms; N = 80 for the performance test), III the next 5 days with 5 h of sleep (N = 120 for subjective symptoms; N = 80 for the performance test), and IV the last 4 days with 8 h of sleep (N = 96 for subjective symptoms; N = 64 for the performance test). Statistically significant differences in means are shown (p < 0.05 and p < 0.001)