Eli5 why grown ups do not fall down from the bed?

Question

I am wondering why small kids ( even a few years old) fall down from the bed while changing their position but bigger children /adults do not, no matter how much they move while sleeping?

In: 2276

Answer 1

I did fall out of bed once as an adult, when pregnant. I thought I was in the middle of the bed, rolled over to get to the edge, and fell right out of bed onto my side. Fortunately the babies were fine.