Life on space station means astronauts get an hour's less sleep than on Earth

Astronauts struggle to sleep because weightless life at 17,500mph exhausts the human body clock, research finds
Astronauts Thomas Jones and Mark Polansky during their “sleep shift” on the ISS in 2001.
Nasa
Mark Blunden @_MarkBlunden25 September 2020

Astronauts struggle to nod off in space and get less deep sleep compared to being in their own bed on Earth, research has found.

Scientists from Harvard and Nasa studying how microgravity — the sensation of weightlessness — impacts the body’s circadian rhythms found the “sleep architecture” of people aboard a space station was seriously affected as they orbited 250 miles above Earth.

Living and working in bright, artificial light while travelling at a consistent 17,500mph — 13 times the speed of Concorde — for long periods all added to the physical toll.

The lead author of the study, titled Changes in Sleep Architecture During Long-Duration Spaceflight, said the findings show how humans are affected by the “danger of stress and shift-work” and the importance of good “sleep hygiene” while zooming through the cosmos.

To examine sleep deprivation, scientists analysed historical mission data from four Russian cosmonauts and one astronaut aboard the former space station Mir, via head-mounted “nightcap monitors” worn by subjects, monitoring eye and body movement for 113 nights at home and 63 nights in space.

Microgravity makes mission specialist Ron Garan’s arms drift upwards on the ISS in 2008
Nasa

The study found subjects had a "sleep deficit" of about an hour less while aboard Mir, often lying at unusual angles due to microgravity, compared to being horizontal in their own bed.

On average, this meant about 5.4 hours of nightly sleep in space, rather than 6.6 hours on Earth, despite spending similar times resting.

Subjects also spent “significantly more time awake in bed”, resulting in a “reduction in sleep efficiency” of more than 20 per cent, the study found.

Five astronauts strapped into sleeping bags on the space shuttle Atlantis in 2002
Nasa

The depth of their sleep, measured by dream-state rapid eye movement, was also less.

Crew sleeping bags are strapped to the walls of space stations, so astronauts do not float away, and arms drift upwards in microgravity.

British astronaut Tim Peake described trying to sleep in quarters about the size of a phone box during his mission on the International Space Station.

He said: “The difficult thing, of course, about sleeping space is getting to sleep.

Russia's Mir space station as seen from space shuttle Endeavour in 1998
Nasa

“We don’t lie down. We don’t put our head against a pillow - all of those triggers that you get here on Earth to fall asleep.

“We simply zip up the sleeping bag and wait until we fall asleep, so that can quite hard.”

Harvard’s findings highlight the challenges of ensuring humans who might colonise Mars in future missions on Elon Musk’s SpaceX rockets arrive without significant body clock damage.

Cosmonauts undertook exhausting spacewalks fixing Mir while orbiting at 17,500mph, but still struggled to sleep
Nasa

On Mars, every day — or Martian sol — is about 40 minutes longer than back on Earth, and human passengers first must endure a seven-month, 140 million-mile journey to reach the Red Planet.

Russia’s Mir space station was decommissioned in 2001 after more than 15 years in space, completing more than 86,000 orbits of Earth.

At the end of its service, Mir mostly broke up in the atmosphere and surviving fragments fell into the Pacific Ocean.

The current International Space Station orbits Earth orbits at a similar speed.

Four astronauts at various angles show how microgravity affects rest cycles in space, aboard the shuttle Discovery in 1993
Nasa

Research lead author Oliver Piltch, an undergraduate researcher at Harvard College, said: “We found significant decreases in sleep efficiency during spaceflight despite similar times in bed.

“The sleep deficits that our subjects were facing while working around the clock in a high-pressure environment provide further evidence for the danger of stress and shift-work schedules for humans anywhere.

“(Also) the sleep deficits experienced by our subjects draw attention to the need for a habitable spaceflight environment that is conducive to sleep hygiene.

“Good quality sleep is crucial to the safety and success of all future missions.

“Before travelling to Mars, it is important to further investigate the changes to sleep architecture that we noted in this study.”