When astronauts are in outer space for long periods of time, they often develop vision problems. Scientists have figured out how to avoid this.

Astronauts in space can develop space-related neuro-eye syndrome (SANS). The fact is that on Earth, blood and cerebrospinal fluid normally enter our head when we lie in bed at night. In the morning, excess fluid flows back into the lower body.

But in the weightlessness of space, this fluid remains in the head and constantly puts pressure on the back of the eyes – the condition over time can cause flattening of the eyeballs and swelling of the optic nerves. This often leads to visual impairments such as myopia.

The problem usually resolves itself, as soon as the astronauts return to Earth for a while. But in space, they can have difficulty completing certain tasks where they need to rely on vision. In addition, SANS is thought to also affect brain and heart function.

Therefore, the authors of the new work have created a special sleeping bag for astronauts. It consists of a regular sleeping bag with a rigid frame and padding on top, the latter being closed around the user’s waist. As soon as the lower part of the human body is inside the apparatus, the air is pumped out of the sealed bag and a vacuum is formed. The idea is that the vacuum will draw fluids away from the user’s head to the lower body, essentially giving the eyes a break from the pressure while sleeping.

During testing, the device was tested on 10 volunteers. They spent a total of six days in the supine position. Since they did not get up, fluids could accumulate in their heads, as in zero gravity.

Half just lay on the bed, and the other spent eight hours each night in a sleeping bag. After the experiment, the authors examined their eyes using optical coherence tomography and found that part of the eye – the choroid – was less swollen when the person used a new sleeping bag.