The Difficulties of Sleeping in Space

The strange atmosphere of space can cause some problems for astronauts, and you can tell this by looking at the pills they take during their time spent in space -- almost half of the medication prescribed to astronauts is sleep aids and hypnotic medicines [source: Canadian Space Agency]. Most difficulties stem from the fact that living onboard a space station, despite the familiar atmosphere, can be very disorienting, even to astronauts who undergo months or even years of training.

For one, the International Space Station usually sees the sun "rise" once every 90 minutes -- that's about 16 sunsets every day. To counteract this, ISS administrators set astronauts' schedules on a 24-hour, Earth-based timetable to keep their activity as grounded as possible. The clocks onboard the ISS are set to Greenwich Mean Time (GMT), about halfway between Houston, Tex., and Moscow. To keep astronauts on that schedule, Mission Control sends wake-up calls to shuttle missions. They typically play music, which is either requested by an astronaut or an astronaut's family member. Astronauts on the ISS, on the other hand, wake up with the help of an alarm.

To avoid any distracting light and heat from the sun, astronauts will cover up any windows they're near. The personal sleeping compartments in the Zvezda module all have windows, so blocking out the sun is important. Astronauts can also choose to wear black sleep masks, the same kind that some people wear on Earth when they want to shut out distracting light. On top of excessive light, strange noises are a big part of the ISS. Because fans, air filters and other noisy equipment provide life support to the astronauts, the ISS is often filled with constant whirring noises. In fact, astronauts often compare the insides of the spacecraft to a giant vacuum. Astronauts sometimes sleep with earplugs to dampen the sound, but after a while they simply get used to it, much in the same way a person can adjust to living near a busy railroad track.

Despite taking sleeping pills, astronauts still get less sleep than they do on Earth. Although their schedules reflect an 8 to 8.5-hour period of sleep, they usually report receiving only 6 hours a night. On the plus side, some studies actually suggest that astronauts receive a better quality slumber -- the effects of microgravity can reduce sleep-disordered breathing like sleep apnea because air travels easier through upper airway passages in space.

It's also possible for astronauts to snore in space, and NASA has even recorded crewmembers doing so, but the effects of zero gravity also appear to reduce snoring [source: American Journal of Respiratory and Critical Care Medicine].

For lots more information on living in space, see the next page.