Yes, but as has been mentioned, sensitivity to it is very much an individual thing. it's partly your fitness level and partly just you. I live at 2200 ft and regularly sleep over 8000, and I notice no ill effects whatsover (I sleep like a baby and feel just fine, no headaches). On the other hand I don't think I have *ever* slept at 10,000 - the rockies here just aren't that high..

The advice given so far is really probably the best. if you *don't know* how you do at altitude, work up to it slowly. Me? I'll go bashing up to 8 or 9 because I know from past experience that I'll do fine with it. Were you taking me up say, 11 or 12k, I'd probably not want to head straight up to that altitude, I'd plan my route so I slept a night or two at 8 or 9 before going higher. But again, it's an individual thing, and very much about knowing *your* body and how you react. You can mitigate somewhat by being fit, but it's still individual, and caution is the best course until you *know* how you react.