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 fell out of bed 3 months after a hip replacement. I landed kind of on both my knees but thankfully I was wrapped in my duvet cover so quite padded.

Adult. Just an idiot.