I'm a 64-year-old guy.
I generally sleep through the night without getting up.
I had no bad aftereffects from sleeping in Santa Fe, N.M. (elevation 7000') for several nights last summer.
If somebody upgrades me to a sleeper seat on my next trip over the Pacific, I'll take it. (Memo to the world's airlines: you'll probably have a few chances to do this in 2007. PM me if you want to take advantage of this valuable opportunity.)