A sleeping bag that mimics the pull of gravity could prevent astronauts’ eyes from bulging in space, reducing the risk of vision problems on long journeys.
About 70 per cent of people in space experience changes to the shape of their eyeballs, sometimes affecting their vision.
When we lie down on Earth, there is a threefold increase in pressure inside the skull because our body fluids are redistributed. This pressure is usually relieved when we get up in the morning, but in microgravity this doesn’t happen to the same degree. This leads to excess body fluids collecting in the head and puts pressure on the eyes.
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“It’s not a major problem now as you can just put on corrective lenses,” says at UT Southwestern Medical Center in Texas. “But in the future, with longer space trips, it could become a big issue.”
To solve this problem, Levine and his colleagues designed a sleeping bag that covers the lower half of the body and applies suction using a vacuum. This vacuum mimics the pull of gravity, sucking body fluids away from the head when a person lies flat.
The team tested the sleeping bag on 10 people on Earth. Although the researchers couldn’t replicate the microgravity conditions of space, they asked the subjects to lie down flat for 72 hours straight. “This recreates a similar pressure on a person’s eyeballs as being in space would,” says Levine.
They then repeated the experiment with the same participants after at least a 10-day gap, but this time without the sleeping bag.
The researchers measured eye shape using an optical coherence tomography scan and found that using the vacuum-sucking sleeping bag led to a less dramatic change in eye shape.
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Brain blood flow and blood pressure measurements showed that the sleeping bag caused no other issues. “We don’t know if this will work for longer periods of time, but we need to find out,” says Levine.
“We do know that crew have difficulty sleeping in space for various reasons,” says “And this will only become a bigger issue when we start going on longer missions beyond Earth’s orbit, so we need to help our bodies handle it.”
JAMA Ophthalmology
