| I am suffocating. The thought transfuses into me intravenously. It is cave-black and hot and wet and there is the throb of an underground river and my arms are bound along my sides and I can't breathe. I don't understand what's happening until I jerk my head around and see a masked assailant behind me. He has pulled a plastic bag over my head and twisted it tight around my neck, and now I'm trying to scream, my mouth stretched open—but there's no air and I can't believe this is how I will die, with my brain popping and my lungs collapsing simply for lack of a little oxygen....
I wake. The sweat-drenched sleeping bag is twisted like a tourniquet around my torso. I grope for my headlamp, switch it on, check the time, find my notepad, and pencil in: "Night 10, 23:35, 13.6% O2, 18,200 ft, can't breathe, hellish headache."
I take a swallow from my water bottle, force myself to take another, kick off the sleeping ba apnea, with fatigue, dizziness, and violent bouts of nausea still left to look forward to. All these symptoms may pass, or they may not; AMS is a fickle torturer. And there's only one sure cure: descent. It's the middle of the night and I am loath to lose altitude, but my body is clearly telling me that I'm not yet capable of sleeping at 18,200. No sleep tonight and tomorrow I'll feel hollow-headed, agitated, buzzy—the perfect mental malaise for screwing up.
I reluctantly swing my feet out of my sleeping bag, open the door, step out of the room, and instantly plunge 11,000 feet.