Sleeping on the ISS

Space Station at night

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13 January 2014

Have you ever suffered from jetlag after flying across many different time zones? Such long distance journeys often lead to problems in sleeping at night and a feeling of drowsiness during the day. But what happens on the International Space Station, where crews experience 16 sunrises and sunsets every 24 hours?

Astronauts can suffer from sleeping problems in space, just as we do. Stress, heavy workloads, background noise, light and air quality can all upset their internal body clocks. Minimising sleep disturbances for astronauts is one of the goals of the European Astronaut Centre's medical team.

Although day and night have little meaning in orbit, each crew follows a 24-hour clock based on Greenwich Mean Time. Monday to Friday they have a very structured routine, working up to 10 hours, followed by a sleep period of eight hours. Meals take place at set times, as do relaxation periods, debriefings and slots for communication with family and friends, for privacy and for leisure activities.

Nespoli inside sleeping bag in Harmony

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Saturday is spent on more work, maintenance, cleaning and private time. Sunday is planned as a rest day, although many astronauts are happy to undertake voluntary science and maintenance. However, the daily schedule can be upset by unforeseen events and arriving spacecraft.

Sleeping tablets are usually not necessary, though a common drug named melatonin is available if feelings of jetlag occur. However, side-effects from taking medications can result in drowsiness and difficulties on waking up. The Astronaut Centre tests medicines for side-effects because they can differ between astronauts.

The space medical community is also experimenting with light of different colours. Blue lighting on the Space Station – resembling bright sunlight - could influence the body to be more alert, whereas red lighting might induce sleep.

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