On Earth, gravity pulls fluids down into the body each time a person gets out of bed – something known as “unloading”. But in space, the low gravity allows more than half a gallon of body fluids to gather in the head, applying pressure to the eyeball.
![Space sleeping bag to solve astronauts' squashed eyeball disorder 1 122026308 sleepingbag1](https://i0.wp.com/ichef.bbci.co.uk/news/1024/branded_news/139EA/production/_122026308_sleepingbag1.jpg?fit=%2C&ssl=1)