Before revision: Astronauts have reported having nightmares , dreams, and snoring while sleeping in space.NASA - Sleeping in Space Sleeping and crew accommodations need to be well ventilated; otherwise, astronauts can wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide had formed around their heads.
After revision: Astronauts have reported having nightmares and dreams, and snoring while sleeping in space.NASA - Sleeping in Space Sleeping and crew accommodations need to be well ventilated; otherwise, astronauts can wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide had formed around their heads.