Astronauts in space need to sleep near fans so that when they exhale, there isn’t a CO2 cloud in front of their face causing them to potentially suffocate. – WTF Fun Facts
Source: https://www.quora.com/Do-astronauts-on-the-ISS-need-to-sleep-with-a-fan-on-or-in-some-way-have-moving-air-around-them
