When astronauts stay in outer space for extended periods, they frequently develop a vision problem known as spaceflight-associated neuro-ocular syndrome (SANS). Scientists are now trying to keep that from happening, via an experimental vacuum-sealed sleeping bag.
Here on Earth, it's normal for blood and spinal fluid to flow into our head while we're lying flat in bed at night. When we get out of bed in the morning and stand up, gravity causes the excess fluid to flow back down into our lower body, so everything stays as it should.
In the zero-gravity environment of space, though, that extra load of fluids never leaves the head. The liquid continuously places pressure on the backs of the eyes – a condition which over time can cause flattening of the eyeballs and swelling of the optic nerves. This often results in visual impairments such as nearsightedness.
The problem usually resolves itself once the astronauts have been back on Earth for a while. While they're still in space, though, they may have difficulty performing certain vision-dependent tasks. Additionally, it is believed that SANS may also affect brain function, plus it could lead to heart problems.
That's where the high-tech sleeping bag comes in.
Developed by Dr. Benjamin Levine and colleagues at the University of Texas Southwest Medical Center, it consists of an airtight sleeping bag with a rigid frame and a gasket at the top which seals around the user's waist. Once the person's lower body is inside the apparatus, air is pumped out of the sealed bag, creating a vacuum. The idea is that this vacuum will draw fluids away from the user's head and into their lower body, essentially giving their eyes a break from the pressure while they sleep.
In a test of the technology, 10 volunteers spent a total of six days in a supine (lying on the back) position. Because they never stood up, fluids were able to accumulate inside their heads, as would happen in space.
For three of those days, the volunteers simply lay on a bed all day and night. For the other three, however, they spent eight hours each night in the sleeping bag. When their eyes were subsequently examined via optical coherence tomography, it was found that a part of the eye known as the choroid was considerably less swollen over the period that the sleeping bag was used – swelling of the choroid is known to precede SANS-related vision problems.
It is now hoped that once further studies have been conducted, the technology could ultimately be utilized to ensure the well-being of astronauts.
"This is perhaps one of the most mission-critical medical issues that has been discovered in the last decade for the space program," says Levine. "I’m thankful for the volunteers who are helping us understand, and hopefully, fix the problem."
A paper on the research was recently published in the journal JAMA Ophthalmology.
Source: UT Southwest Medical Center via EurekAlert
