Sleeping in space is challenging for astronauts, possibly putting the space travelers in danger. A 10-year study found crew members working on the Space Shuttle while in orbit slept less than six hours during each 24-hour period. Travelers aboard the International Space Station did not fare much better, averaging just over six hours each day. American space agency NASA schedules 8.5 hours of sleep each night for astronauts.
Brigham and Women's Hospital (BWH) researchers examined 21 astronauts who had taken part in flights to the International Space Station and 64 Space Shuttle astronauts over 80 missions.
Three-quarters of all astronauts on the ISS took sleeping pills attempting to rest. That percentage was slightly higher - 78 percent - for those traveling aboard space shuttles. Health officials for the agency are concerned these drugs, and sleep deprivation, could be posing hazards to astronauts.
"The ability for a crew member to optimally perform if awakened from sleep by an emergency alarm may be jeopardized by the use of sleep-promoting pharmaceuticals. Routine use of such medications by crew members operating spacecraft are of particular concern, [given a FDA] warning that patients using sleeping pills should be cautioned against engaging in hazardous occupations requiring complete mental alertness or motor coordination," Laura Barger, associate physiologist at the BWH Division of Sleep and Circadian Disorders, said.
At home on Earth after their flights, ISS astronauts slept more than seven hours 50 percent of the time, while Shuttle astronauts slept at least that amount of time 42 percent of nights. Those numbers were just 24 and 12 percent during space missions, the report revealed.
Sunrises and sunsets are seen every 90 minutes by space travelers aboard the International Space Station. This could be the cause of sleeping difficulties, although no one is yet certain what is causing the problem.
Sleep deprivation started before the flight, according to Barger and her team. During three months of training, astronauts slept just 6.5 hours per night.
Zolpidem and zaleplon were among the sleeping aids available to space travelers. They were consumed by occupants of the space shuttle on 42 percent of all nights, on average.
"Future exploration spaceflight missions to the moon, Mars or beyond will require development of more effective countermeasures to promote sleep during spaceflight in order to optimize human performance. These measures may include scheduling modifications, strategically timed exposure to specific wavelengths of light, and behavioral strategies to ensure adequate sleep," Charles Czeisler of the BWH Division of Sleep and Circadian Disorders, said.
Study of astronaut sleeping patterns and the use of tranquilizers by space travelers was profiled in the journal The Lancet.