7 Strange Things That Happen to Your Body in Space

7 Strange Things That Happen to Your Body in Space

Space travel can cause behavior changes, bone loss, rashes and more.

Entrepreneur and cosmos enthusiast Elon Musk has a mission: by late 2018, he plans to send two non-astronaut civilians into space for a week-long flight around the moon. 

Of course, those everyday folks are going to need serious training. Thanks to things like radiation and lack of gravity, funky things happen to human bodies in space. That's part of why it can take months and years of preparation before astronauts are ready for liftoff. 

With that in mind, here are seven strange things that can happen to our bodies during a relatively short space mission.

We can be exposed to a lot of dangerous radiation
Earth's atmosphere shields us from most cosmic radiation, including gamma rays and ultraviolet radiation–a good thing, since exposure can increase the risk of cardiovascular disease, central nervous system damage, and much more.

Once you leave Earth's protective magnetic field, however, your chances of developing radiation-related health problems increases. This is true even for a shorter trip, like one around the moon. One study of Apollo mission astronauts found the radiation actually caused blood vessel damage; they even showed a higher cardiovascular mortality rate.

Space travel can cause bone and muscle loss
An astronaut can lose more than one percent of his or her bone mass in a month of space travel. What's more, NASA reports that being among the stars for 5 to 11 days can cause a staggering "20 percent loss of muscle mass." 

These losses make exercise important for astronauts, since it helps them avoid atrophy of the bones and muscles. That's why they work out for two hours each day, using a variety of equipment specially designed for microgravity. 

Sleeping becomes a challenge
Due to new surroundings, long flight times and high stress, many astronauts experience disturbed sleep, sleep deprivation and even long-lasting fatigue. Because of this, they're often only able to get six out of the seven to nine recommended hours of slumber. 

Your behavior changes
Flying a shuttle may sound like fun, but being confined to such a small area can leave explorers feeling isolated, cramped, and stressed. The close quarters and potential for grievous error can hurt interpersonal relationships, making astronauts irritable towards each other. It may not stop in space, either. This change in behavior can carry over on Earth, one reason astronauts must have psychological evaluations before launch.

Vision could get worse
It’s believed that being in space causes pressure along the optic nerve, which can result in blurred vision and, in some cases, permanent damage to the eyes. One NASA survey of both short- and long-flight astronauts found many had problems seeing things up close and far away during flights–and for some, those issues persisted on the ground. 

In a separate, small study involving crew members from a long-term flight, NASA found the backs of some astronauts' eyeballs actually flattened, in addition to other changes. Again, the effect didn't go away for a while upon returning to Earth.

Immune systems weaken and congestion increases
High levels of radiation, increased stress, confined spaces and lack of gravity can increase allergy symptoms, and even the possibility of rashes. Some even theorize that longer missions could result in a heightened risk of infections or autoimmune problems later on down the road–which is currently being studied.

Not only does space change your immune system, but pressure can cause the fluids in your body to spread out and move towards your head. This could cause a puffy face and congestion, which should return to normal on Earth.

Space makes you taller
If you feel short on Earth, consider a trip through the galaxy. Since gravity isn’t as strong in space, it allows your spine to relax and stretch instead of being pushed down, as it would be on Earth. The result is a growth spurt of about two inches over a year.

Before you get too excited, keep in mind that you'll go back to your original height when you return home. 

Medically reviewed in February 2019.

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