The effect of spaceflight and simulated microgravity exposure on thermoregulation in humans: a systematic review

Even a minor increase in core body temperature (CBT) raises physiological challenges in astronauts, leading to a decline in physical and cognitive performance. This study aims to systematically review and summarize existing literature on the effects of spaceflight or its simulations on human thermoregulation. This systematic review was performed according to the PRISMA guidelines and Space Biomedicine Systematic Review methods. The search was performed using three databases: PubMed, Web of Science, and Cochrane Library. During the database search, 832 studies were identified. A total of 20 studies were included in the systematic review (spaceflight exposure: 6 studies, bed rest: 14 studies). One of the primary observations from spaceflight studies was the elevation of CBT during prolonged missions. The observed increase in CBT has been attributed to multiple factors, including disruptions in circadian regulation, changes in the immune system, and reduced evaporative cooling due to altered sweating responses. Five of the spaceflight simulation studies show an increase in the CBT after bed rest, and no change was observed in 3 studies. To mitigate risks associated with the dysregulated thermoregulatory system, future studies analyzing the integration of advanced monitoring technologies, personalized thermal management strategies, and evidence-based countermeasures are needed.