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How long do astronauts sleep for?

Astronauts have very unique sleep schedules compared to people on Earth. Their sleep is often disrupted due to the extreme environment of space and the demanding mission schedules. However, getting adequate sleep is critical for astronauts’ performance, health and safety.

Typical Sleep Schedules for Astronauts

On the International Space Station (ISS), astronauts typically follow a preset sleep schedule based on Greenwich Mean Time (GMT). A normal sleep period is between 6-8 hours, usually split into two shorter blocks.

Here are some examples of common sleep schedules for ISS astronauts:

  • Bedtime: 9:30pm GMT
  • Wake up: 5:30am GMT
  • Nap: 1:00pm – 3:00pm GMT

This allows for about 7 hours of total sleep time per 24-hour period. However, sleep is often fragmented with many disruptions and not as restorative as on Earth.

Challenges of Sleeping in Space

There are several factors that make sleeping in space very challenging for astronauts:

  • Microgravity environment – The free-floating environment causes discomfort and can make it difficult to get comfortable and rest.
  • Disrupted circadian rhythms – The busy mission schedule and frequent orbital day/night cycles disrupt the body’s natural sleep-wake cycle.
  • Noise and temperature fluctuations – The ISS is a noisy environment with fans, pumps, and electronics running. Temperature variations also occur.
  • Light exposure – Despite window shades, the bright sun and lights on the ISS can make the sleep environment too bright.

These conditions lead to poor sleep quality and duration for many astronauts in space. Fatigue from sleep loss can impair performance and mood.

Sleep Monitoring in Space

Given the risks of inadequate sleep, astronaut sleep is carefully monitored on the ISS and in spaceflight studies:

  • Wrist actigraphy – Devices worn to track sleep/wake cycles
  • Sleep logs – Astronauts keep journals detailing sleep quality and timing
  • Surveys – Astronauts complete questionnaires about sleep adequacy
  • Video monitoring – Cameras record sleep postures and movements

This allows researchers to study the effects of spaceflight on sleep and determine if interventions are needed to improve astronaut sleep health and performance.

Improving Astronaut Sleep in Space

There are some strategies used to try to improve sleep for astronauts in space:

  • Blocked sleep periods – Consolidating sleep into longer blocks versus fragmented sleep
  • Naps – Adding planned nap periods to allow for recovery sleep
  • Sleep aids – Pharmacological interventions to improve sleep initiation
  • Eye masks and ear plugs – Reducing light and noise disturbances
  • Exercise and nutrition – Maintaining performance and circadian regulation
  • Sleep monitoring and counseling – Tracking data trends and identifying solutions

However, getting truly restorative sleep remains a challenge due to the constraints of the space environment. More research is needed to find better solutions to optimize astronaut sleep health and performance for future long-duration missions.

Sleep Differences Between Astronauts and Mission Control

An interesting difference exists between the sleep patterns of astronauts in space versus flight controllers working in NASA’s Mission Control Center on Earth:

Astronauts in Space Flight Controllers on Earth
Live on Greenwich Mean Time (GMT) schedule Work on Houston local time
Sleep is fragmented and disrupted Aim to get consolidated, continuous sleep
Experience daylight about every 90 minutes as they orbit Earth Follow normal day/night cycle
Exposure to microgravity and space radiation Earth normal gravity and radiation
Very noisy sleep environment Quiet sleep environment

These differences in schedules, environments, and physiology lead to very different sleep experiences for astronauts versus ground controllers – both groups face unique challenges getting adequate rest to perform their duties.


In summary, astronauts have to sleep in a challenging environment but getting sufficient, high-quality sleep is crucial. Typical ISS astronauts sleep 6-8 hours split into two blocks, following a GMT schedule. Disruptions like microgravity, noise, circadian misalignment, and light make getting restorative sleep difficult. Strategies like naps, sleep aids, exercise, monitoring, and counseling aim to improve sleep health but problems persist. Differences also exist between spaceflight and ground mission control sleep experiences and environments. More research on astronaut sleep optimization will be key for future missions.