Expose yourself to direct natural light outdoors (without sunglasses or windows) immediately upon waking—5 minutes on a bright sunny day, 10 minutes on a cloudy day, and 20 to 30 minutes on a very overcast day—to regulate your biological clock.

noli's read

The recommendation to seek out morning light to synchronize one's biological clock is solidly validated by expert consensus (e.g., expert opinion, PLoS Biology 2022). Researchers such as Satchin Panda have shown that our ocular receptors are stimulated by natural blue light to promote wakefulness and regulate our rhythm. However, the claim that windows block the necessary "wavelengths" is scientifically inaccurate: standard glass allows the essential blue light to pass through. In reality, windows drastically reduce light intensity (lux), making it up to 50 times less effective than being outdoors. Finally, the precise durations of 5 to 30 minutes depending on the weather are a very practical rule of thumb (e.g., expert opinion), even if they are not based on strict randomized controlled trials. This logical graduation remains an excellent guideline for adapting one's exposure to the weather.

the sources

1. 1NIH Office of Dietary Supplements 2026
2. 2Manson JE et al. 2019
3. 3Bhatt DL et al. 2019
4. 4Khan SU, Lone AN, Khan MS, et al. 2021
5. 5Liao Y, Xie B, Zhang H, et al. 2019
6. 6hubermanprotocols.com (fan reference guide)