Facing the sun with closed eyelids would get you a lot of red light in the generally correct spectrum https://www.spiedigitallibrary.org/journals/journal-of-bi

Facing the sun with closed eyelids would get you a lot of red light in the generally correct spectrum https://www.spiedigitallibrary.org/journals/journal-of-biomedical-optics/volume-16/issue-06/067011/Measuring-and-predicting-eyelid-spectral-transmittance/10.1117/1.3593151.full https://www.spiedigitallibrary.org/journals/journal-of-biome... Probably wouldn’t do it for more than 10 mins