How stressful are 105 days of isolation? Sleep EEG patterns and tonic cortisol in healthy volunteers simulating manned flight to Mars

摘要: Spaceflights "environment" negatively affects sleep and its functions. Among the different causes promoting alterations, such as circadian rhythms disruption microgravity, stress is of great interest also for earth-based medicine. This study aims to evaluate relationships between related social/environmental confinement in six healthy volunteers involved simulation human flight Mars (MARS500). Volunteers were sealed a spaceship simulator 105 days studied at 5 specific time-points period. Sleep EEG, urinary cortisol (24 h preceding EEG recording) subjectively perceived levels collected. Cognitive abilities emotional state evaluated before after simulation. parameters time (latency, duration) frequency (power hemispheric lateralization) domains evaluated. Neither cognitive functions alterations nor abnormal found. Higher associated to: (i) decrease duration, increase arousals, shortening REM latency; (ii) reduction delta power enhancement sigma beta NREM N3; (iii) left lateralization activity (NREM REM) right (NREM). Stressful conditions, even with fluctuations normal range, alter structure spectral content, mirroring pathological conditions primary insomnia or depression. Correlations changes suggest covert risk developing allostatic load, thus need develop ad-hoc countermeasures preventing long lasting manned space missions.