I live at 118' and have hunted 3 years in a row anywhere from 9000 to 11500. The first 2 years we stayed at 7200 in the valley and went by truck to the high country. I had a pretty good dose of sickness the first year. my friend has a cabin at 9300 feet and I feel I do better now since i stay high all day and all night. I usually get a slight headache the first day or two but am OK after that. i took my wife out there to work on the cabin and she got sick her first day and spent the whole day in bed with the splitting headache, puking and muscle aches. I had a resident from out there tell me to take an aspirine and rolaid a couple of times a day and that is what the locals tell their friends who visit.