You climb out of bed and immediately fall over. Both of your legs are completely numb—fast asleep. You wait for a minute or two, massaging them back to life. Your head aches, but not as if you’re hungover or anything. Not a headache. It’s more as if you hit your head at some point. Or as if someone—or something—hit your head, you think. Your legs feel mostly normal now. You stand and feel the back of your head. There’s a huge lump that’s sore to the touch. Ouch.