Altitude

Sun Beams in the Valley

Rapid ascent can lead to altitude sickness. The best treatment is to descend immediately. The climber's motto at high altitude is "climb high, sleep low", referring to the regimen of climbing higher to acclimatise but returning to lower elevation to sleep. In the South American Andes, the chewing of coca leaves has been traditionally used to treat altitude sickness symptoms.

Common symptoms of altitude sickness include severe headache, sleep problems, nausea, lack of appetite, lethargy and body ache. Mountain sickness may progress to HACE (High Altitude Cerebral Edema) and HAPE (High Altitude Pulmonary Edema), both of which can be fatal within 24 hours.

In high mountains, atmospheric pressure is lower and this means that less oxygen is available to breathe. 

This is the underlying cause of altitude sickness. Everyone needs to acclimatise, even exceptional mountaineers that have been to high altitude before. Generally speaking, mountaineers start using bottled oxygen when they climb above 7,000 m. Exceptional mountaineers have climbed 8000-metre peaks (including Everest) without oxygen, almost always with a carefully planned program of acclimatisation.