Let the Light Turn Off at 21

Mary Carskadon's research reveals an uncomfortable truth: your teenager's late nights aren't rebellion but biology. Puberty shifts the body's melatonin release later, creating a clock that genuinely runs behind adult schedules. Add the blue light from evening screens, which Harvard studies show suppresses the sleep hormone and delays drowsiness further, and you get a compounding problem. Matthew Walker's work on sleep debt explains the morning irritability, the forgotten backpack, the sullen breakfast silence. The fix isn't willpower; it's light management.

You'll learn:

- Why the adolescent circadian shift makes early wake times biologically brutal

- How the phone-in-bed triple trap combines light, stimulation, and social fear

- What morning sunlight does to pull the internal clock forward