SLEEPING IN WON’T FIX LOST SLEEP When I was a teenager, I envied my friends who could “sleep in” on the weekends. I didn’t have that luxury. From age twelve until my seventeenth birthday, I had a morning paper route. Every day—including Saturdays and Sundays—I was up at 5 a.m., folding papers, loading them into the bags on my bike, and pedaling through the neighborhood to finish deliveries by six. Once I got to college, I finally discovered the joy of staying up past midnight for several nights and then sleeping in on weekends until ten. At that age, it...