Why is red light used for night vision? Why not yellow or other colours of light?
In: Technology
Your rods rely on rhodopsin, and your cones rely on photopsin. The longer you spend in the dark, the more of these chemicals end up in your eyes, and the more sensitive your eyes become. Exposure to light photobleaches these chemicals. That’s why adjusting to a bright environment happens very fast, but adjusting to a dark one takes much longer.
Your rods are what you mostly use for night vision. Red light does not photobleach rhodopsin, so your rods remain sensitive.
How useful this is compared to just having a really dim yellowish light, I’m not sure. I have a flashlight with a “firefly” mode that I use if I wake up in the middle of the night and need to move around the house.
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