| Research Abstract |
To investigate the changes revealed in circadian variations of biological variables, when a sleep phase was shifted, seven male students (ave. 21.1yo, 169.5cm, 65.8kg) were studied for 72 hours continuously under a controlled physical conditions and living environment in 1999. Sleep hours were from 00:00 to 07:00 on the 1st day, zero on the 2nd day, and from 12:00 to 19:00 on the 3rd day.
Blood pressure and pulse rate had the clear biphasic variation with the low period during sleep, and adjusted abruptly to the new schedule. Adjustment of circadian variations to changed sleep-wake schedules occurred at different rates by subject. Oral temperature and cortisol kept significant circadian variations for 3 days, with the phase delay of 2 hours per day. Some blood and urinary variables showed combined variations with blunted amplitudes after the phase shift, with adjustment of circadian variations at different rates in the different variables. Subjective vigilance lowered rapidly during prolonged night, and recovered more slowly and less effectively after the shifted sleep. The reactions to the phase shift also depended on persons.
We surveyed timings of daily life in 310 university students. On holidays they woke up ca. 1〜2 hours later than on weekdays. 70% of them had breakfast on weekdays, and 49% on holidays. Those who did not eat breakfast woke up ca. 2 hours later than those who had breakfast.
We will further analyze rhythmometric characteristics of variables examined, and explore the relations between variables or symptomes, taking into account of interindividual variability, and will report the results.
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