I get that you realize the moment you actually fall asleep, but before that—from the time you lie down until you drift off—you’re in some sort of position, right? My two most comfortable sleeping positions are on my side (either left or right) and lying on my back; I can fall asleep in any of them, but while I’m lying there trying to sleep, I keep shifting positions until I finally doze off. What about you?

I don't understand those people who sleep on their back 😛 I'm always a side sleeper.

I sleep with one of my arms under my pillow.