I like Bonita62's answers. An informal way of saying the same thing: "I'm already counting Z's by the time my head hits the pillow." (The sound of a person sleeping is "Zzz.") And for children who have trouble falling asleep, parents sometimes tell them to count sheep. In cartoons, you might see someone in bed imagining sheep jumping over a fence.

1.- "I fall asleep as soon as I get in bed", but it sounds better when you say "As soon as I get in bed, I fall asleep" 2. "I fall asleep as soon as my head touches the pillow", and so does "As soon as my head touches the pillow, I fall asleep"

I fall asleep as soon as I get into bed. I fall asleep as soon as my head hits the pillow.