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CHANGES OF MOOD STATES DURING THE PERIOD OF SLEEP DEPRIVATION UP TO 48 HOURS.  S.Zhang, X.Y. Wu, X.Y. Li and L.P. Han.  Department of Aerospace Biodynamics, The Fourth Military Medical University, Xi’an 710032, P.R.China

   Introduction: Manned space flights have shown it is possible to sleep in microgravity. However, some sleep disturbances, i.e. sleep deprivation, sleep reversal, naps, and circadian rhythm alternation, have been reported which influence performance of the crew and safety of space flight. Moreover, psychosocial factors are also likely to play an increasingly important role in determining mission success. The main purpose of the research was to study the effects of sleep deprivation up to 48 h on human mood state. Method: Fourteen healthy male subjects (aged 19-21) underwent sleep deprivation up to 48 hours. During which their mood states were evaluated by self-assessment questionnaire, profile of mood state (POMS). The POMS consists of 65 adjective words with 5-point scale degrees of agreement, resulting in 6 types of mood states, i.e. T: tension-anxiety; D: depression-dejection; A: anger- hostility; V: vigor-activity; F: fatigue-inertia and C: confusion- bewilderment. Results: The positive mood state factor points (V) changed to a remarkably lower level at the 20 h of sleep deprivation (P<0.01) and declined to the 30% level of control at the end of sleep deprivation. The negative mood state factor points (T, F, C) increased significantly from the 24 h of sleep deprivation (P<0.05) and reached their highest level at the 48 h of sleep deprivation (P<0.01). Meanwhile, the points of A and D had a tendency to increase but not to a significant extent. Conclusions: Sleep deprivation up to 48 hours can disturb human mood state. This suggests that sleep deprivation may be detrimental psychologically for the individual as well as for the operational success and safety of the missions.

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