The Physiology of High Altitude on Everest
Above 8,000m, human life cannot be sustained. This is the 'Death Zone'. On a Mount Everest expedition, climbers enter this zone for the final push, racing against their own deteriorating bodies.
The body starts consuming its own muscle for energy. Digestion shuts down. Thinking becomes slow. Even with bottled oxygen, you are slowly dying every minute you stay near the Mount Everest summit.
Hypoxia causes poor judgment. Climbers feel warm when they are freezing or want to sleep in the snow. This is why strict turnaround times are enforced by guides during Everest trekking peaks and expeditions.
You cannot recover in the Death Zone. If you get sick or exhausted, the only cure is to descend. Rescue is incredibly difficult because helicopters cannot land this high.
Surviving the Death Zone requires physical fitness, mental discipline, and the wisdom to turn back if needed.