How is it possible that...

my scalp fell asleep? I woke up one morning last week and had a strange feeling on my head, right side, just above the hairline. I had never felt that before, and realized after doing a few ‘eyebrow’ excercises that my scalp had fallen asleep. It started tingling, and then I went back to sleep. I think I’d fallen asleep on the piping of the pillow and somehow cut off the circulation. Weird.