How sleeping bags could help astronauts>>>Scientists

An astronaut's eyes can change during spaceflights that last six months or more.

That could be a problem for future planned missions.

After decades of research, scientists may have a seemingly unlikely solution: a sleeping bag, developed in conjunction with REI, that pulls fluids away from the brain.

A concern that has emerged regarding astronauts is how their eyes change during long-duration spaceflight, lasting six months or longer, and potential impacts to their eye health over time. 

Crew members typically spend four to six months on the International Space Station, but future planned missions lasting a year or longer warrant more investigation, according to researchers.

How the human eye changes after 1 year in space

How the human eye changes after 1 year in space

The impact on the health of astronauts' vision as a result of long-term spaceflight previously was known as visual impairment and intracranial pressure, or VIIP, syndrome. Researchers now refer to ophthalmologic and neurologic findings in astronauts after long-duration spaceflight as spaceflight-associated neuro-ocular syndrome, also known as SANS.

This condition includes swelling of the optic nerve, flattening of the eyeball and vision impairment, all of which are likely caused when the lack of gravity causes fluids in the body to largely remain in the upper body while astronauts are in space.

Vision problems, including difficulty reading, the need for assistance during experiments, and far-sightedness, have been documented in more than half of the astronauts who spend an average of six months on the space station.

Astronauts like Scott Kelly, pictured here during a 2015 spacewalk, have experienced vision issues in space.

Astronauts like Scott Kelly, pictured here during a 2015 spacewalk, have experienced vision issues in space.

This rush of fluids to the head isn't an issue for us on Earth because gravity pulls fluids down through the body. If you've ever laid down with your head tilting backward, you can just stand up to alleviate the pressure -- but that's not possible in space.