By Chris Skeldon 
Scientists have developed a high-tech sleeping bag that could prevent eye problems that some astronauts suffer during their stay in space.
In a zero-gravity environment, fluid floats inside the head and compresses the eyeball over time. This is considered one of the most serious health problems affecting astronauts, and some experts believe it may hinder trips to Mars.
The sleeping bag balances the fluid in the head and transfers it to the feet, controlling increased pressure. It was developed by Benjamin Levine, MD, professor of medicine at Southwestern Medical Center at the University of Texas at Dallas. Levine is working to transport equipment to the International Space Station (ISS).
More than half of the astronauts who have spent at least six months on the International Space Station have reported vision problems with NASA. Some had difficulties seeing from afar, reading, and needed help completing space mission experiments.
said Levin, who is also a manager Institute of Exercise and Environmental Medicine.
“It would be a disaster if the astronauts were so seriously compromised that they couldn’t see what they were doing, compromising the mission.”
In 2005, astronaut John Phillips began his mission on the International Space Station with normal vision, also called 20/20 vision, and returned six months later with 20/100 vision. The normal eye can see at a height of 100 metres.
Others had less severe versions of the problem. On Earth, gravity pulls bodily fluids down every time a person gets out of bed – this is known as “discharge.” But in space, low gravity allows half a gallon of body fluid to accumulate in the head, putting pressure on the eyeballs.
This can lead to a condition called ‘space travel-associated neurogenic eye syndrome’. (neurocular syndrome associated with spaceflight) or SANS, its English acronym. This, in turn, can lead to a gradual flattening of the back of the eyeball, swelling of the optic nerve, and double vision.
“The pressure in zero gravity is always less than the pressure in gravity. But it’s not as low as when you’re standing. NASA astronauts can’t stand during flight,” Levine told BBC News.
constant pressure
Although the brain pressure of a person lying on Earth is slightly greater than that of a person lying in space, astronauts experience constant pressure that they cannot relieve by standing upright.
“They never have a chance to ’empty’ (fluid flow) out of the brain,” says Levine. “So we asked, ‘Can we re-enter the gravitational gradient’?”
The sleeping bag is wrapped around a person’s waist, covering the lower part of the body with a rigid frame.
The suction device, which works on the same principle as a vacuum cleaner, creates a pressure difference that displaces the liquid towards the feet. This prevents fluid from accumulating in the brain and “crushing” the eyes.
Some questions must be answered before this technology can be used routinely, such as how much time astronauts must spend inside the device each day.
“Does everyone need to do this or just the people who are willing to develop SANS? Do you need to do this once you’re in space, or can you wait to see if your vision changes?” Example Levine, speaking of still unanswered questions. “This kind of thing has yet to be determined.”
But Levine says the creation of the sleeping bag means SANS may no longer pose a health risk on NASA’s future mission to the Red Planet.
People with cancer and those who survive played an important role in elucidating the causes of this medical condition. The volunteers still had access to the head used to administer chemotherapy drugs, and this allowed the scientists to measure pressure in the brain as they spent a few seconds in a zero-gravity flight simulation.
Dozens of other volunteers tested the same technology. The scientists took the measurements while they were lying down with and without the sleeping bag. The researchers found that although lying down for three days was enough to slightly change the shape of the eyeball, no change occurred when the suction technique was used.
A team of researchers at Southwestern Medical Center previously discovered that microgravity causes the heart to contract in space, which could cause a condition called atrial fibrillation — a type of irregular heartbeat.
A sleeping bag can also help control abnormal blood flow, which increases the risk of arrhythmias of low severity. Research on this was published in the academic journal JAMA Ophthalmology.