Sleep deficiency in spaceflight may correlate with degraded neurobehavioral functions and elevated stress

1. In this study, astronauts reported on average sleeping for 6.5 hours in flight.

2. Furthermore, sleep duration of less than 6 hours led to greater reductions in psychomotor response speed, elevated stress, mental fatigue, physical exhaustion, and higher workload in astronauts during flight.

Evidence Rating Level: 2 (Good)

Astronauts need to maintain optimal levels of neurobehavioral functioning for successful spaceflight missions. Adequate sleep quality and duration are critical, but astronauts typically experience short sleep durations (<6 h) in space. This longitudinal study investigated the sleep-wake behaviors, neurobehavioral functions, and ratings of stress and workload amongst astronauts on the International Space Station (ISS).

Twenty–four astronauts (19 males, 5 females) from multiple international space agencies who were scheduled for 6-month ISS missions from 2009 to 2014 were included. The Reaction SelfTest (RST) was utilized to assess 1) sleep timing, quality, and duration; 2) neurobehavioral performance (PVT-B) on the astronauts before, during, and after spaceflight, and 3) visual analog scale (VAS) ratings of behavioral states. Astronauts reported on the time to bed and out of bed, along with the time taken to fall asleep, time spent awake due to sleep disturbances, and time spent in bed after awakening. Data collection began 180 days before launch, continued every 4 days in-flight aboard the ISS, and up to 90 days post-landing.

Overall, astronauts reported sleeping approximately 6.5 h in-flight. Sleep durations <6 h correlated with greater reductions in psychomotor response speed, higher workload, and elevated stress compared to astronauts who received 7-8 h of sleep. Moreover, sleep durations <5 h led to more negative somatic behavioral states, such as greater physical exhaustion ratings, mental fatigue, and tiredness. However, this study was limited in that it relied on self-reported sleep-wake behaviors from astronauts. Nonetheless, this study was significant as it was the largest study to date of astronaut sleep and neurobehavioral functions during spaceflight missions, demonstrating an association between inadequate sleep and impairments in attention and behavioral functions.

Click to read the study in Sleep

Image: PD

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