Headaches and eye problems are common among visitors to the International Space Station. Astronaut Chris Hadfield remembers the headaches in his five months of spaceflight on the International Space Station in 2012 and 2013. It was a constant pain in his sinuses, along with stuffiness. The Canadian astronaut blew his nose frequently to clear his head and used mild pain medication to help him keep up with his demanding spaceflight schedule.

It gets better over time, but it never goes away. It is just a natural effect of weightlessness. They are going to have a clogged head, which is a lot of people leads to a throbbing headache. The cause of the headaches say, researchers, could be that during spaceflight gravity isn’t pulling fluids through the body in the same way as on Earth.

In space, astronauts are floating in microgravity and fluid, such as blood, that would be pulled towards the feet remains in the head. Bed rest patients, when lying in a head-down position, also have blood pulled towards their head.

Future Astronauts Might Turn Feces Into Food

Eye problems among astronauts are also a pressing issue for NASA because some of them come back from orbit with permanent changes in vision.  Without gravity's cues, in other words, many astronauts feel sick when they first arrive in orbit. But motion sickness tends to fade as the mission continues, allowing astronauts to somersault or do spacewalks without problems.

"A headache is a common symptom during space travel, both isolated and as part of space motion syndrome," the investigators wrote in the 2015 study, which was intended to compare bed-rest subjects to the International Space Station astronauts. 

"Head-down-tilted bed rest (HDTBR) studies are used to simulate outer space microgravity on Earth and allow countermeasure interventions such as artificial gravity and training protocols aimed at restoring microgravity-induced physiological changes."

Space Sickness

The researcher suggested that his headaches and motion sickness in space are related. He remembers his first mission to the Mir space station in 1995 when high carbon dioxide levels along with his movements in weightlessness around the large space station made him sick on his third day in space.  He added that while headaches and motion sickness are both symptoms of weightlessness, it's hard to prove a headache caused by motion sickness.

Headaches

Headaches are common among astronauts, Hadfield said, but space agencies are becoming smarter in how to deal with them. Mild pain medications are always in stock on the International Space Station. Crew doctors keep track of pain severity, although Hadfield says it varies from person to person and it's hard to come up with an objective scale.>

While the headaches are somewhat painful, nothing in Vein's results suggests permanent damage or an exaggerated effect on astronauts’ work. Once the causes of headaches are pinned down, NASA will likely implement more countermeasures for astronauts in orbit. The space station is in operation until at least 2024, giving NASA some time to perfect any treatment.