Abstract
In a series of experimental shift-work studies, individual differences in adapting to a new schedule were examined after a time shift of 12 hours. Four male students (A.D)participated on a normal schedule (sleeping period:00:30-07:30) for two days and on a shif tschedule (sleeping period:12:30-19:30) for two days.Mah-jong game was loaded in most awaking times.Oral temperature was measured and urine was collected every 4 hours except during sleep.At the same time, the subjects completed a fatigue feeling scale and a sleepiness scale.No obvious individual differences on the circadian variations of oral temperature, and urinaryadrenaline and 17-OHCS were observed on the normal schedule.However, the variations in these physiological indices on the shift schedule were classified into two types.Whereas the circadian period of oral temperature rhythms in subjects A and B which was equal to 24-hours was maintained, these rhythms in subjects C and D shifted and had two peaks in a day. The variations in adrenaline and 17-OHCS excretion in A, B-group were also different from thosein C, D-group.The acrophases of the excretion rhythms in A, B-group were preceded by those in C, D-group.The subjective ratings of fatigue and sleepiness in subjects A and B tended to be higher than those in subjects C and D on the shift schedule.
