Sleep suffocation
Stories from Physics
for 11-14
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Astronauts on the International Space Station must sleep by a ventilator. The microgravity on the spacecraft means exhaled carbon dioxide does not move away from a sleeping astronaut and, without air circulation, they could suffocate in a bubble of their own carbon dioxide.
References
Sleep suffocation
Daily Life, Astronauts, 15th November 2012, Human Spaceflight and Exploration, ESA website, http://www.esa.int/Our_Activities/Human_Spaceflight/Astronauts/Daily_life