title: Physical exercise accelerates reentrainment of human sleep-wake cycle but not of plasma melatonin rhythm to 8-h phase-advanced sleep schedule.
abstract: Effects of timed physical exercise were examined on the reentrainment of sleep-wake cycle and circadian rhythms to an 8-h phase-advanced sleep schedule. Seventeen male adults spent 12 days in a temporal isolation facility with dim light conditions (<10 lux). The sleep schedule was phase-advanced by 8 h from their habitual sleep times for 4 days, which was followed by a free-run session for 6 days, during which the subjects were deprived of time cues. During the shift schedule, the exercise group (n = 9) performed physical exercise with a bicycle ergometer in the early and middle waking period for 2 h each. The control group (n = 8) sat on a chair at those times. Their sleep-wake cycles were monitored every day by polysomnography and/or weight sensor equipped with a bed. The circadian rhythm in plasma melatonin was measured on the baseline day before phase shift: on the 4th day of shift schedule and the 5th day of free-run. As a result, the sleep-onset on the first day of free-run in the exercise group was significantly phase-advanced from that in the control and from the baseline. On the other hand, the circadian melatonin rhythm was significantly phase-delayed in the both groups, showing internal desynchronization of the circadian rhythms. The sleep-wake cycle resynchronized to the melatonin rhythm by either phase-advance or phase-delay shifts in the free-run session. These findings indicate that the reentrainment of the sleep-wake cycle to a phase-advanced schedule occurs independent of the circadian pacemaker and is accelerated by timed physical exercise.
authors.affiliation: Dept. of Physiology, Hokkaido Univ. Graduate School of Medicine, Sapporo 060-8638, Japan.
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Yamanaka
authors.forename: Satoko
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tanahashi
authors.forename: Shin-Ya
authors.initials: SY
authors.lastname: Nishide
authors.forename: Sato
authors.initials: S
authors.lastname: Honma
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Honma
mesh_terms: D001831:Body Temperature / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D008550:Melatonin / Q000097:blood*; D017440:Photoperiod; D012007:Rectum; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
chemical_list: D008550:Melatonin