In Alexia Casale’s The Bone Dragon, the 14-year-old narrator says, “I’m tired in that unpleasant, irritable way you get when you sleep somewhere too warm.”

I never knew that sleeping somewhere too warm would make people cranky. I know I sometimes can’t fall asleep if I am too warm, because I insist on sleeping under covers. I always feel strange without at least a sheet, but I prefer I nice soft blanket.

I thought what makes people cranky is being woken up during REM sleep, like when my toddler runs into the room because he has to go poop and I JUST fell asleep.

Do you know what makes you cranky when you wake up?