Physiological changes, sleep, and morning mood in an isolated environment.
BACKGROUND
Previous isolation studies have shown increased 24-h urine volumes and body weight gains in subjects. This project examined those and other physiological variables in relationship to sleep motor activity, subjective sleep quality, mood, and complaints during confinement.


METHODS
Six male and two female subjects lived for 7 d in the National Space Development Agency of Japan's isolation chamber, which simulates the interior of the Japanese Experiment Module. Each 24-h period included 6 h of sleep, 3 meals, and 20 min of exercise. Each morning, subjects completed Sleep Sensation and Complaint Index questionnaires. Catecholamine and creatinine excretion, urine volume, and body weight were measured on the 2 d before and 2 d after confinement, and sleep motor activity was measured during confinement.


RESULTS
Confinement produced no significant change in body weight, urine volume, or questionnaire results. In contrast, epinephrine, norepinephrine, and sleep motor activity exhibited significant differences during confinement (p < 0.05). Higher nocturnal norepinephrine excretion correlated with higher sleep motor activity.


CONCLUSIONS
The 24-h epinephrine values were slightly higher than normal throughout the experiment, but lower than for subjects working under time-stress. High sympathetic activity (as indicated by norepinephrine) may have interfered with sleep.
Kraft
Norbert O
NO
Human Factor Research and Technology Division, NASA-Ames Research Center, Moffett Field, CA 94035-1000, USA. nkraft@mail.arc.nasa.gov
Inoue
Natsuhiko
N
Mizuno
Koh
K
Ohshima
Hiroshi
H
Murai
Tadashi
T
Sekiguchi
Chiharu
C
D000328:Adult; D000339:Affect / Q000502:physiology*; D000704:Analysis of Variance; D001835:Body Weight / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D004837:Epinephrine / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D009638:Norepinephrine / Q000652:urine; D012016:Reference Values; D012894:Sleep Stages / Q000502:physiology*; D012934:Social Isolation; D011795:Surveys and Questionnaires; D014556:Urine / Q000502:physiology
D009638:Norepinephrine; D004837:Epinephrine