As any good cardiologist would tell you, blood flow is key to your health.  They probably won’t tell you that gravity is key to blood flow.  But that’s probably because they don’t usually have to deal with patients that aren’t subject to gravity.  When people are no longer subject to gravity, such as astronauts resident on the ISS, that lack of gravity can become a problem, especially when dealing with sensitive soft tissues such as the eyes.  To solve that problem, a team of scientists and engineers have the University of Texas Southwestern have developed a special type of sleeping bag that might help astronauts with their blood flow issues caused by gravity, and potentially get their sight back.

One of the many indignities that isn’t much discussed in spaceflight is that more than half of the astronauts living on the space station for more than six months have suffered from vision problems.  The problems appeared to be related to a condition called spaceflight-associated neuro-ocular syndrome, or SANS.  It occurs when a person’s eyeball is flattened by consistent pressure from their circulatory system.


Depiction of the problem astronauts face with blood flow to their eyes in space.
Credit – NASA / UT Southwestern

It might not only be the eyes that are impacted by this pressure.  Some astronauts suffer from a condition known colloquially as the “space stupids,” where they make simple mistakes that they feel they would not have made back on Earth.  Since the brain could suffer from the same pressure affecting the eyes, the underlying cause of SANS might have even more deleterious effects than originally thought.

Luckily, for those of us still Earthbound, gravity helps pull the blood, causing the pressure down to the rest of our bodies, allowing time for our brain and eyes to recover while standing or sitting up.  However, doctors can replicate the effects of SAN by requiring a patient to lay prone in a bed for slightly more than three days.  


The problem with being in orbit during medical check-ups is sometimes you have to do your own. Here astronaut Serena Auñón-Chancellor examines her eye with a “funduscope” on the ISS.
Credit – NASA

Dr. James Leidner, an internal medicine hospitalist, volunteered for this arduous task and spent three days on his back in bed trying to replicate the condition.  He did so twice, with researchers measuring his brain activity at the end of each three-day period.  He was fitted by a specially designed sleeping back for eight hours a night during the second experiment.

That sleeping bag was designed by Dr. Benjamin Levine and his team of specialists in astronaut health.  It is intended to force bodily fluids to move into the lower body, relieving the pressure they cause on the brain and eyes.  To do so, it compresses the legs in a pattern to force blood to flow more directly to them, distributing the blood more like t would be on Earth.

https://www.mansbrand.com/space-flight-destroys-your-red-blood-cells/

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