Altitude sickness, also known as acute mountain sickness or altitude anoxia, is a condition stemming from a lack of oxygen in the blood and tissues due to low atmospheric pressure. Night vision is impaired, followed by breathlessness, headache, and faintness. At 5,000 m, mental changes include indifference, euphoria, and faulty judgment but complete acclimatization is possible up to those heights. At very high altitude (6,000 m to 7,000 m), cyanosis, coma, and death rapidly supervene. Treatment is by oxygen and descent. The use of pressurized cabins in aircraft prevents the occurrence of this condition on high-altitude flights.