Joint NASA-ESA-DARA Study. Part three: circadian rhythms and activity-rest cycle under different CO2 concentrations.

作者：A. Samel, Martin Vejvoda, K Wittiber, Jürgen J. Wenzel · 发表于：PubMed · 年份：1998 · 被引用次数：9 · 研究领域：Spaceflight effects on biology、Space Exploration and Technology、Indoor Air Quality and Microbial Exposure

BACKGROUND: During manned space missions, the actual concentration of carbon dioxide (CO2) is frequently elevated to a degree that may affect human functioning and productivity. Therefore, a ground-based international study was performed that tested various psychological and physiological functions under the condition of two different levels of CO2. Thus, a specific experiment aimed at the influence of enhanced CO2-concentrations on the sleep-wake cycle and the circadian system. METHODS: Four volunteers were subjected to a CO2 concentration of 0.7% and 1.2%, respectively, for 24 consecutive days under each condition. Before they were exposed to these elevated levels, baseline measurements were conducted during 5 d under ambient CO2 concentrations (<0.1%). Circadian parameters were assessed by continuous recording of body temperature and by the determination of excretion rates of cortisol, 6-hydroximelatoninsulfate and catecholamines at 3-h intervals during wake. These measurements were conducted on 3 consecutive days 4 times during the two campaigns. Nondominant wrist activity and subjective fatigue was monitored throughout both study phases. RESULTS: Daily means of activity showed significant differences between the two study conditions (with lower values during the 1.2% condition), but these differences only occurred during day-time, whereas during sleep activity levels remained the same. Diurnal mean and circadian amplitude of the temperature rhythm was also significantly ...