Abstract
Detecting the influence of psychological stress is particularly important in prolonged space missions. In this study, we determined potential markers of psychological stress in a confined environment. We examined 23 Japanese subjects staying for 2 weeks in a confined facility at Tsukuba Space Center, measuring salivary, skin, and facial image parameters. Saliva was collected at four points in a single day to detect diurnal variation. Increases in salivary cortisol were detected after waking up on the 4th and 11th days, and at 15:30 on the 1st and in the second half of the stay. Transepidermal water loss (TEWL) and sebum content of the skin were higher compared with outside the facility on the 4th and 1st days respectively. Increased IL-1β in the stripped stratum corneum was observed on the 14th day, and 7 days after leaving. Differences in facial expression symmetry at the time of facial expression changes were observed on 11th and 14th days. Thus, we detected a transition of psychological stress using salivary cortisol profiles and skin physiological parameters. The results also suggested that IL-1β in the stripped stratum corneum and facial expression symmetry are possible novel markers for conveniently detecting psychological stress.
Highlights
An increasing number of studies have examined health risks to astronauts during space flight as multiple spacefaring nations extend space travel development with a view to undertake human missions to Mars and the Moon
The results indicated that the salivary cortisol surge after awakening increased from C2 to C13, compared with figures obtained outside the confined facility
We found possible non-invasive biomarkers to measure the effects of psychological stress in the confined environment
Summary
The Japan Aerospace Exploration Agency (JAXA) has focused research on identifying biomarkers for self-assessment of stress so that astronauts can check their stress level by themselves when they are unable to receive regular professional face-to-face interviews on their psychological health by medical doctors. As part of these initiatives, JAXA performs experiments in the confined facility (JAXA-CFE) at the Tsukuba Space Center (Tsukuba, Ibaraki, Japan) that precisely controls the experiment conditions and tracks the subjects’ behaviors in detail. We have continued investigations and report the results in this paper
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