A close-up view of the International Space Station. / HO AFP/Getty Images
Drowsy drivers, you have company - in space.
Astronauts in space get scant sleep, and the majority take sleeping pills to cope, says a 10-year study to be published Friday in Lancet Neurology.
The largest-ever look at astronaut sleep habits was conducted through 2011, when the last U.S. space shuttle flew. It finds shuttle astronauts slept just less than six hours on an average night and that International Space Station astronauts slept only a few minutes more. About 75% took sleeping pills, mostly zolpidem (better known by the brand name Ambien).
The study, funded but not conducted by NASA, raises some safety concerns for future missions, researchers say.
"In ground-based studies, we know that sleeping less than six hours is associated with performance detriments," says lead author Laura Barger, a research fellow at Brigham and Women's Hospital and instructor at Harvard Medical School in Boston.
Heavy sleeping pill use is a concern, too, she says. "If an astronaut had to be awakened in the middle of the night for some emergency situation, their performance could be impaired."
Even next-day drowsiness is a potential issue, she and her colleagues note. They quote from a Food and Drug Administration warning on zolpidem that says "patients should be cautioned against engaging in hazardous occupations requiring complete mental alertness or motor coordination such as operating machinery or driving a motor vehicle."
Zolpidem has also been associated with "sleep-driving," according to the FDA.
The study included 64 shuttle astronauts and 21 space station astronauts of various nationalities. The participants kept sleep and medication logs. They also wore movement monitors to confirm sleep times.
While the researchers did not collect data on performance, they have evidence astronauts were sleep-deprived. One clue: Once back on Earth, they slept more - just like many sleep-deprived workers do on weekends, Barger says.
Also, journals kept for another study show astronauts often complain about sleepiness, the authors say.
Christopher Winter, a sleep medicine specialist from Charlottesville, Va., who was not involved in the research, says the methods used for quantifying sleep in the study are not as precise as sleep lab studies. He also says people in new and stressful situations tend to underestimate their sleep. But he doesn't doubt that "getting launched out of the Earth's atmosphere" contributes to some sleeplessness.
NASA rules say astronauts' schedules must include 8.5 hours for sleep. Work demands and conditions such as cold, heat, noise and, of course, weightlessness, might get in the way, Barger says. So, she says, more solutions are needed, especially as the agency plans longer missions, including an eventual trip to Mars.
In a statement, NASA said it is "committed to fully understanding the impacts of long-duration spaceflight on our astronauts. ... Our astronauts work in harsh, complex environments where they are sometimes subjected to uncomfortable and high stress situations. The agency works hard to identify and implement countermeasures that can ensure astronauts are able to get the same quality and quantity of sleep in space as they do on Earth."
Read the original story: Sleeping pills in space: Astronauts are regular users