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 (38F) do fall out of bed regularly, but I have terrible proprioception. I also walk into doorframes, miss (or nearly miss) the chair when trying to sit down, and kick table legs and other furniture all the freakin time.