Quirks & Quarks·Analysis

High-tech astronaut sleeping bag may alleviate health problems on long journeys to Mars

Bob McDonald's blog: Life in microgravity leads to vision problems and potentially other serious health issues, such as body fluids accumulating in the upper body. The sleeping bag may counteract this problem

Bob McDonald's blog: Device may help with vision problems due to microgravity

Researchers in the US have been developing a sleeping bag that uses vacuum pressure to pull fluids into the lower body. Astronauts spending extended time in migrogravity suffer from eye problems because fluids accumulate in the upper body and put pressure on the eye. (UT Southwestern Medical Center)

An experimental sleeping bag uses suction to reduce fluid pressures on the brain and may help eliminate astronaut vision problems caused by extended time in zero-G. The researchers developing it think it could help with potential cardiovascular and cognitive issues that might be issues on long-term space flights as well.

Astronauts living aboard the International Space Station often comment on how pleasant it is to sleep in microgravity. Floating freely, with no pressure on the body from gravity, there is no need for a bed or pillow. Instead, the sleeping quarters have a zippered bag attached to the wall, which they crawl into for the night. The bag is to provide warmth and to prevent their bodies from floating around the room while they sleep. Open holes on the sides of the bag allow the arms to float up in front of the body as though they are conducting an orchestra in their sleep. It is apparently a completely relaxing experience.

Japanese astronaut Koichi Wakata sleeps in an ordinary sleeping sack on the International Space Station. (NASA)

However, that same microgravity environment can play havoc with their bodies. Fluids in the body that are normally pulled downwards by gravity here on Earth tend to flow upwards to the chest and head in space, giving the astronauts puffy faces and what they call "bird legs."

You can see the roundness in Canadian Astronaut Chris Hadfield's face from his time aboard the International Space Station, compared to when he is on the ground.

Canadian astronaut Chris Hadfield spent six months in space as commander of the International Space station in 2012-2013. (NASA)

The extra fluids in the head can put pressure on the eyeballs causing vision problems and, in some cases, even cause distension of the optic nerve. 

Canadian astronaut Roberta Bondar found she didn't need her glasses during her flight on space shuttle Discovery in 1992, likely because the fluid pressure in the eyeball paradoxically improved her vision.

About half of astronauts on long duration flights have experienced vision problems while in orbit, which usually disappear once they return to Earth. But that doesn't bode well for future travellers on a six- to seven-month journey to Mars.

One possible treatment to relieve the fluid pressure in the head is a variation on the sleeping bag developed at the University of Texas Southwestern Medical Center. 

Under microgravity fluid accumulated in the head and upper body, increasing pressure on the eye, which can cause vision problems for astronauts. (NASA/UT Southwestern Medical Center)

It involves a hard, covered frame that surrounds the lower body and uses suction to draw the body fluids toward the lower extremities. Researchers studied its effects on volunteers who lay in bed for extended periods, simulating the fluid shift toward the head that happens in space and can cause a slight change in the shape of the eyeballs. One of the participants was the research scientist, who made two visits of three days each, with only the second and third days in the device for eight hours each night. While in the vacuum machine, there was no change in the eyeballs.

Vision problems among astronauts have been known for decades and are a serious issue, possibly even a game changer for long flights to Mars. Poor vision could make it difficult to operate equipment or deal with an emergency.

But the researchers are hoping that the benefits of their system might go beyond vision. They point to evidence that long-duration space travel can create cardiac abnormalities, and astronauts who've reported mild cognitive impairments – what they call the "space stupids," which also might be caused by body fluids being in the wrong place in microgravity. 

The device is still a laboratory experiment, and will first have to be adapted for spaceflight and tested on astronauts in orbit to see if it provides benefits.

Hopefully these vision problems will be solved before a Mars mission is attempted. After all, no one wants to make the long journey all the way to Mars and not be able to see the scenery once they get there.


Bob McDonald is the host of CBC Radio's award-winning weekly science program, Quirks & Quarks. He is also a science commentator for CBC News Network and CBC-TV's The National. He has received 12 honorary degrees and is an Officer of the Order of Canada.