| Project/Area Number |
08457018
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | Hokkaido University |
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Principal Investigator |
HONMA Ken-ichi Hokkaido Uni.Sch.of Med., Professor, 医学部, 教授 (40113625)
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| Co-Investigator(Kenkyū-buntansha) |
KATSUNO Yumiko Hokkaido Uni.Sch.of Med., Instructor, 医学部, 助手 (80177419)
HONMA Sato Hokkaido Uni.Sch.of Med., Associ.Professor, 医学部, 助教授 (20142713)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1997: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1996: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Biological clock / Sleep-wake rhythm / Social cue / Circadian rhythm / melatonin / rectal temperature / Entrainment / Internal desynchronization / 社会的同調 / 自励振動 / メラトニンリズム / 内的同調 / 位相反応 |
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| Research Abstract |
Circadian rhythms as well as sleep were analyzed in healthy male subjects who spent 9 to 15 days without knowledge of time under temporal isolation facility. The light intensity was below 100 lux. The sleep-wake and rectal temperature rhythms were monitored continuously. Blood was sampled sequentially through an indwelling catether for 36 hours and plasma melatonin was determined. Immediately after the determination of baseline rhythms, the sleep-wake schedule was phase-advanced by 8 hours with an over night stay-up inbetween. Forced internal desynchronization was induced by fixing sleep phase either for l, 4 or 7 days, and then the subjects were released into free-run conditions.
Entrainment of sleep-wake rhythm was judged from the initial phase of free-running sleep rhythm. The sleep rhythm was entrained in all subjects when the sleep phase was fixed for 7 days, and in half of subjects when fixed for 4 days. The sleep rhythm was not entrained at all when the sleep phase was fixed only for 1 days. On the other hand, the circadian rhythms in plasma melatonin and rectal temperature were not entrained even when the sleep phase was fixed for 7 days but the free-run periods were significantly affected.
From these results, it becomes apparent that the sleep-wake rhythm can entrain to social time cues, but takes several days of transient until completely entrained. This entrainment does not seem to be mediated by the oscillation mechanism responsible for the ciracadian rhythms in plasma melatonin and rectal temperature. These findings support the hypothesis that the human biological clock consists of two self-sustained oscillators which are mutually coupled and whose zeitgebers are different.
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