Ordinarily, trekking into high alpine zones requires days or even weeks of altitude acclimatization to help you adjust to the fewer oxygen particles you'll be taking in each breath. Weird things happen to your body and without acclimatizing, hikers and mountaineers can easily fall foul to symptoms of debilitating altitude sickness – headache, nausea, dizziness and insomnia among them.
According to CDC recommendations, at least 11 nights of acclimatization is suggested before ascending to heights above 18,000 feet, officially considered “extreme high altitude.”
