What Astronauts Can Teach Us About Sleep
Our exploration of space has given us many things like Velcro and LEDs, but the most important thing we, as a species, may get from our spaceflights is a concrete view of what happens when we don’t get enough sleep. A groundbreaking study into the effects of long-term spaceflight indicates that sleep and adhering to a sleep-wake cycle aligned with the light/dark timeframes found on Earth are both critical to physical and mental health and neurocognitive abilities.
The study was part of a larger research initiative developed by the Institute for Biomedical Problems of the Russian Academy of Sciences and partially sponsored by the European Space Agency. The goal of the larger initiative was to simulate a 520-day spaceflight so that data could be gathered on the psychological and medical effects of long-term spaceflight. A 6 man team of volunteers entered the simulation environment in June of 2010 to perform experiments and run scenarios. Data from the simulation was gathered for use by many international research teams looking into different aspects of the effect of long term spaceflight on the human body and mind.
One of the research teams involved in the simulation was comprised of team members from the Perelman School of Medicine at the University of Pennsylvania and Baylor College of Medicine. This team analyzed the data from the simulation to determine how sleep and cognitive performance are impacted by the conditions inherent to an extended spaceflight like confinement and lack of sunlight. Their findings were published in the online version of the Proceedings of the National Academy of Sciences and highlight the importance of maintaining a healthy sleep-wake cycle during prolonged spaceflight.
In order to better understand how conditions in long-range spaceflights will affect the astronauts, the team looked at how stress, fatigue, and sleep loss affected the mood, mental health, and cognitive performance of the participants. By using wrist actigraphy, light exposure, and neurobehavioral assessments, the team monitored the sleep quantity, quality, sleep-wake cycles, alertness and cognitive performance throughout the duration of the mission. Analysis of the data indicated that as the simulated flight progressed, the crew members became more sedentary and spent more time resting or sleeping. Unfortunately, the increase time spent resting and sleeping did not equate to better sleep overall as all participants experienced sleep disturbances, degraded quality of sleep, difficulties with alertness, and issues with their sleep-wake cycle. All of these factors together indicate the crew members may have been experiencing problems with their circadian rhythm.
These findings have important implications for the future of long-term space flight as they underline the need to address the sleep problems documented in the study as part of any future planning for long term spaceflight. The findings also underscore the importance of sleep, activity, and exposure to natural light for everyone. As more and more people are adopting sedentary lifestyles conducted primarily indoors that often interfere with the natural sleep-wake cycle, the results of this study provide valuable insight into what we all need to do to protect our health.