Under sea level conditions humans breath between 10 and 12 times per minute. The breathing cycle in high altitude is accelerated. If the conscious breathing control vanishes during sleep a periodic breathing with alternating episodes of hyperventilation and apnea is the result. This circumstance causes repetitive arousals that do not allow a normal sleep pattern. The associated adverse effects are fatigue, slow or failed acclimatization, weakening of the immune system, lack of motivation and the disability to make rational decisions.