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Circadian rhythms are fascinating, really they are, I could go on all day.
For instance you know how in your retina you have rods and cones that sense light and relay it to your brain through other cells? Well there is a variation on one of these ‘midway’ cells where that cell itself is photosensitive. (intrinsically photosensitive retinal ganglion cells) and these cells while not sensing light for vision do mediate your master circadian rhythm. They work strongly with light in the blue>near infrared range of light. Fun fact, before NASA knew about this they just had the lights on the ISS turned up *really* high (like 20000 lumes) to try to keep people entrained to a 24 hour day when they had a 90 minute day in terms of light, now it’s just high in that part of the spectrum and regular in the rest.