There is exacting selection in NASA for future astronauts. The most important parameter is the health condition of the applicants for space work. Healthy sleep has a directly affect on the NASA demand. Space Station on the Earth’s orbit makes almost 16 rotations around the planet per day. That means astronauts meet the down 15 times on the day.
Such daily schedule is very tough for human body. It can lead to sleep deprivation because of disorder in biological rhythms. Sleep deficiency has a negative exert on the brain and the organism as a whole. Scientists of NASA formulated 5 main rules to obviate fatigue failure.