Question: Why do people randomly faint when they come back from space?

Charles Laing answered on 14 Jun 2016:

Hi Jazz,

When an astronaut goes into space blood moves from the legs and towards the head. This cause them to have a ‘puffy face’ and skinny ‘chicken legs’.

After spending a long time in space the body learns to deal with this new normal and actually reduces the amount of blood flowing around the body. This is the body’s response as it tries to reduce the ‘puffy face’ and cope with the increase of pressure.

Once an astronaut returns to Earth, gravity causes the blood to once again move towards the legs and away from the head. In a way the body has got lazy in space and does not expect the blood to be moved away from the head so quickly.

As the body struggles to get blood back to the head on Earth the returning astronauts can faint after standing too long. When someone faints they go from standing to lying down and this is good as the body does not have to work so hard to get blood to the head. So fainting is the body’s way of saving itself!

Charlie 😀🚀