You go to bed at the same time. The room is dark. Your phone is put away. Nothing obvious has changed. Yet suddenly, you're awake at 3:17 a.m. Maybe you're warm. Maybe you aren't. Sometimes you fall back asleep. Other nights your brain seems to decide that 3 a.m. is the perfect time to review tomorrow's schedule, unfinished work, and every conversation from the previous week. For many women,...