Used to all the time. Think it’s because I had a futon throughout my teens and early 20s and didn’t develop enough height/danger response while sleeping as a result.
That said, Offspring II falls out of bed all the time so maybe it’s genetic 
Haven’t fallen out of bed for ages, but did wake up last week with a big bump on my head which I assume was from banging it on the bedside table so a close call…