Y: Welcome back from space, Don! How was your trip?
D: I’ll tell you in a minute. I have to sit down first—I’m feeling kind of dizzy.
Y: Are you okay?
D: Don’t worry, I’m fine now. It’s normal for astronauts to feel dizzy or faint when they come back to Earth. It’s similar to what happens to people on Earth sometimes when they stand up quickly after sitting or lying down—the blood rushes away from the brain and your blood pressure drops temporarily. For astronauts, the same thing happens because they’re coming from a low-gravity environment.
Y: Is there anything we can do about it?
D: Researchers are working on figuring that out. They did a study recently with 12 astronauts—8 men and 4 women who were all between 43 and 56 years old. The astronauts spent about 6 months in space, during which they followed an exercise regimen that included endurance and resistance training for up to 2 hours a day. When the astronauts returned to Earth, they were also given a saline infusion. The researchers measured the astronauts’ blood pressure before, during, and after their time in space, and didn’t find any significant changes, and none of the astronauts felt dizzy or fainted in their first 24 hours back on Earth. Though more research needs to be done with a larger sample size of astronauts, the researchers say their study implies that countermeasures like an exercise regimen and fluid replenishment can do a lot to help prevent astronauts from fainting.
Y: That’s good to hear. Fainting isn’t the first thing I’d want to do if I were returning to Earth.