Tilting the bed feet up to feel microgravity
Because of the microgravity environment, as soon as astronauts go into space their body starts to go through some changes. One of these changes is the redistribution of fluids inside their body. In particular, some of the fluids migrate towards the head since gravity is no longer holding them down toward the feet, while some fluids are expelled as urine, up to a couple of litres depending on the person. The result of this migration is that there is a higher pressure inside the head compared to on Earth. This may give rise to symptoms like headache, congested sinuses and a general sense of malaise. Usually these symptoms go away after a few days.
While in quarantine, Russian cosmonauts perform a series of ground activities preparing them for going into space. One of these is to tilt the bed were they sleep, so that their feet are about 10 degrees higher than their head. This shifts the body fluids towards the head in a similar way to microgravity does when they arrive in space.
