Why We Sleep Under Blankets?

An excerpt from Atlas Obscura -

Why Do We Sleep Under Blankets, Even on the Hottest Nights?
There’s great comfort in being covered.
BY DAN NOSOWITZ

The other element that might explain our need for blankets is what Hoagland refers to as “pure conditioning.” “Chances are you were raised to always have a blanket on you when you went to sleep,” she says. “So that’s a version of a transitional object, in sort of Pavlovian way.” Basically, our parents always gave us blankets to sleep with—babies are a bit worse than adults at thermoregulation, meaning they get cold easily, meaning well-meaning adults put blankets on them—and so getting under a sheet or blanket is associated with the process of falling asleep. Instead of Pavlov’s dogs drooling at the sound of a bell, we get sleepy when covered with a sheet.

If you Google around for this question, you’ll end up with a bunch of theories about blankets simulating the warm, enclosed feeling we had in the womb. There could be some element of theoretical protection or security imbued by the blanket, which might be another bit of conditioning, but Hoagland thinks the womb comparison is pretty unlikely. “I’m very suspicious of anyone who implies that this goes back to the feeling of being in the womb,” she says. “I think that’s very far-fetched.”

http://www.atlasobscura.com/articles/blankets-summer-hot