Altitude sickness

Above 10,000 feet (3,000 meters) most people experience a periodic breathing during sleep known as Cheyne-Stokes Respirations. The pattern begins with a few shallow breaths and increases to deep sighing respirations then falls off rapidly. Respirations may cease entirely for a few seconds and then the shallow breaths begin again. During the period when breathing stops the person often becomes restless and may wake with a sudden feeling of suffocation. This can disturb sleeping patterns, exhausting the climber. Acetazolamide is helpful in relieving the periodic breathing. This type of breathing is not considered abnormal at high altitudes. However, if it occurs first during an illness (other than altitude illnesses) or after an injury (particularly a head injury) it may be a sign of a serious disorder.

»OA Guide to High Altitude via »Wangjianshuo's blog

That was me when we stayed overnight in Zhongdian (3,200m) - I woke up in the middle of the night with a start because I couldn't breathe. A bit scary. It probably didn't help that I was already having a flu and the temperature was down in the single digits at night.

The Wangjianshuo blog article above makes a nice linkage between high altitude and religion. The very unfortunate incident that happened on his trip also makes me think that travelling with a large party to high altitude may not be the best idea. The »OA Guide advises:

Keep in mind that different people will acclimatize at different rates. Make sure all of your party is properly acclimatized before going higher.

Unfortunately in reality, most trip itineraries are pretty tight and people tend to say "I'm ok" so as not to be the one who slows the the party down. On the trip to Zhongdian, I was the only one (of ten) who was having altitude sickness when we started ascending the Blue Moon Valley. I had the luxury of a halfway station at 3,500m where I could say, 'You guys go ahead. I'll stay here.' Had I no such option and the party had to turn back for me, I think I'd have pushed ahead, to the detriment of myself.

Meanwhile, here is the walking trail and view of the Blue Moon Valley I missed:

{Awaiting photos from cousin J}