You're lying there perfectly still, finally achieving that sacred state of almost-asleep, when your leg decides to audition for the Rockettes without your permission. Your body's apparently been waiting all day for this moment—the one time you've explicitly told it to do absolutely nothing—to practice its surprise kung fu. It's like your nervous system set a reminder: *9:47 PM: kick the mattress, startle the human back to consciousness, repeat in seven minutes.*