Light therapy is the strongest weapon against SAD hypersomnia

Late-winter SAD throws off your circadian rhythm, leading to hypersomnia and a delayed sleep phase, and bright light therapy in the morning is the most effective fix.

Here’s what happens: When you don’t get enough morning light in winter, your suprachiasmatic nucleus (the brain’s master clock) starts running late. Your melatonin production doesn’t shut off when it should, so you stay sleepy longer and feel tired even after ten hours in bed. Your sleep architecture shifts too — more REM, less deep sleep, and a phase delay that makes it hard to wake up naturally.

The research is pretty consistent on what works. A 10,000 lux light box for 30 minutes within an hour of waking, or even better: dawn simulation that ramps up light while you’re still asleep. That’s the most bang for your buck. Melatonin (low dose, early evening) can help nudge the phase forward, but it’s secondary. Sleep hygiene alone won’t cut it