Research

Hormonal

Spaceflight induces significant sleep loss (~6.5 hours/night vs. scheduled 8 hours), reduced slow-wave sleep, and circadian misalignment due to non-24-hour light-dark cycles and low illuminance, leading to neurobehavioral performance decrements.

In high-stress, irregular environments, scheduled sleep time does not equal actual sleep time. Prioritize sleep environment (darkness, quiet) and consistency. If you are in a role requiring high cognitive performance, recognize that 'getting by' on less sleep leads to measurable performance deficits, even if you feel adapted.

GoodSupportsHIGH confidence
Sleep duration, assessed by questionnaires and actigraphy, was only ~6.5 h/day. Subjective sleep quality diminished. Polysomnography revealed more wakefulness and less slow-wave sleep during the final third of sleep episodes... Crewmembers on these flights experienced circadian rhythm disturbances, sleep loss, decrements in neurobehavioral performance, and postflight changes in REM sleep.
Derk‐Jan Dijk et al. · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · 2001

Why this rating

Small sample size (n=5) but rigorous within-subject design with polysomnography and objective measures.

Source

Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights

Derk‐Jan Dijk et al. · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · 2001

DOI 10.1152/ajpregu.2001.281.5.r1647

crossover · n=5Cited 266×
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DOI resolved against Crossref · corpus check 2026-06-10

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