title: Effects of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance: comparison of horizontal and 6 degrees head-down bed rest.
abstract: This study examined the effect of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance. Each of 7 volunteers were maintained for 3 days of head-down and horizontal bed rest in a counter-balanced design. Assessment measures were polysomnographic recordings on the first night and performance on psychophysiological tasks on the second day involving subjective and objective vigilance, P300, simple reaction time tasks, and dual performance tasks. No clear difference in sleep structure was observed between the head-down and horizontal conditions, except for a slight decrease in Stage 4 for head-down. Both subjective and objective daytime vigilance, P300, and the simple RT task showed no statistical difference, although tracking performance on the dual task showed deterioration at 10:00 for the head-down condition. These results suggest that nocturnal sleep, daytime vigilance, and psychophysiological functions were not disturbed in head-down sleep conditions, although there was a mild deterioration of higher attentional function in the morning.
authors.affiliation: Japan Somnology Center, Neuropsychiatric Research Institute, Geriatric Mental Health, National Institute of Mental Health, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. yoko@ncnp-k.go.jp
authors.forename: Yoko
authors.initials: Y
authors.lastname: Komada
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
authors.forename: Koh
authors.initials: K
authors.lastname: Mizuno
authors.forename: Hideki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mishima
authors.forename: Hidetomo
authors.initials: H
authors.lastname: Sato
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Shirakawa
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D001510:Bed Rest; D002540:Cerebral Cortex / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D018913:Event-Related Potentials, P300 / Q000502:physiology; D005583:Fourier Analysis; D018475:Head-Down Tilt / Q000502:physiology*; D006801:Humans; D007699:Kinesthesis / Q000502:physiology; D008297:Male; D017286:Polysomnography; D011187:Posture / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D012894:Sleep Stages / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*; D018474:Weightlessness Simulation / Q000523:psychology*