I figured something unpleasant out about myself this weekend: I suffer from extreme altitude sickness.
We went to a birthday party in the local mountains (Twin Peaks, CA) at roughly 5,100 feet altitude - and no sooner than I got out of my car, I felt like I was going to faint. Pounding heart, dizzyness, shortness of breath etc. I laid down for what I thought was 10 minutes, but it turned out to be about 3 hours. When I awoke, I was no better - so it was decided to take me back down the mountain.
I took some Tylenol, with food - and was better in about 2 hours. Despite sleeping for nearly 5 hours in the afternoon, I slept for 9+ hours last night. Today, I haven't felt "full speed" - but the headache finally went away.
This has happened to me twice before - Taos, New Mexico (approx. 7,000 ft elevation) and at Miyanoshita, Japan (not sure how high up there the cable car was, but I freaked when I had to get on it, and I am not one who suffers from a fear of heights).
So...let's live at sea level!