If you want the practical version before the underlying science, this is it. Everything here is explained and cited properly in the sections that follow. One term you'll see below: lux, the standard unit for how bright light is — ordinary indoor rooms run a few hundred lux, outdoor daylight runs into the thousands.
| Time of day | What to do | Duration |
|---|---|---|
| Within 30–60 min of waking | Get outside, no sunglasses. You don't need to look at the sun directly. | Clear day: 5–10 min. Overcast: 15–20 min. |
| Winter or limited morning access | A 10,000 lux light therapy box, used at the same time each morning | 20–30 minutes, per Section 5 |
| Daytime | Get outside when you can — natural daylight is 10–50× brighter than typical indoor lighting | As available |
| After sunset | Dim overhead lighting; switch to lamps or warm-toned light | From sunset onward |
| Before bed | Reduce bright screen exposure in the hour or two before sleep; use night mode if screens are unavoidable | 1–2 hours before bed |
| Peak sun hours (10am–4pm) | Seek shade or use SPF 30+ for prolonged exposure | As needed |