"Iðunn knows her constant fatigue is a sign that something's not right, but practitioners dismiss her symptoms and blood tests haven't revealed any cause. When she talks to friends about it, the refrain is the same - have you tried eating better? exercising more? establishing a nighttime routine? She tries to follow their advice, buying everything from vitamins to sleeping pills to a step-counting watch. Nothing helps. Until one night Iðunn falls asleep with the watch on and wakes up to find she…Show more