If you're the type of person who enjoys camping, you'd enjoy being an astronaut, because a lot of the things you do when you're camping are the same. We eat freeze-dried food, we don't have running water, there's no fridge, there's no freezer, and we use sleeping bags. Typically we sleep in sleeping bags. I slept in a sleeping bag that was attached to the wall of a sleep station. When you're in a neutral weightless environment, your body goes into something like a fetal position. You're totally relaxed. There is no pressure of the mattress on your body at all. Every night I would put my iPod on; during the first song I'd be asleep, and I'd sleep very well.
On a previous flight we did some sleep studies that involved EEGs, as well, and we did find one thing. You probably know that sleep is associated with various stages. There's one stage of sleep associated with delta waves in the EEGs. We miss that phase of sleep in space, and that's the restful phase, so I would find that I'd wake up tired every day.
But falling asleep was no problem. I'd wake up tired in the morning, but then, you know, you wake up and you think, “Holy crow, I'm in space.”