Shared beds with same-sex friends since jr high. I was a junior in high school when my parents and younger sibs went to the other coast for a school year. My best friend's parents invited me to come live with them. I usually had a sleeping bag on an air mattress in his basement bedroom (he had a queen-size bed, an old one of his parents', I think).
We both slept nude. (all my friends slept in the nude.) Sometimes I just wanted to be warmer, or he did, he'd invite me in (or I'd ask), and I'm climb in his bed and we'd snuggle and spoon.
Sometimes they'd have family visiting, and he'd have to give up his bed. We'd get "assigned" somewhere else and share a bed. He was a big snuggler (as I am!), so it was natural to just strip off and spoon and snuggle each other. Nothing sexual involved.
Had a third friend who often hung out with us, and we sometimes ended up sleeping in a big pile of naked bodies and covers after a late night playing music or cards. Same experience at friend's houses when we'd partied too much for safe driving.
My high school and college friends were pretty casual about sharing their beds if there was a good reason, and it was never a big deal. Most of my friends were straight-identified, though I had some gay friends whose beds I also shared, just for sleeping. Everybody was pretty snuggly, and we usually spooned. None of this "you stay on your side, and I'll stay on my side" stuff.