I have an echeveria plant. Even though it thrives on neglect, I try to ensure my plant has its needs met. Anyone who views my Instagram will see progress photos of my plant from when the echeveria was gimmicky luminous paint to today. While it may not look like a typical echeveria, akin to a blooming onion, the plant is healthy. As far as I know my plant is an Echeveria agavoides which needs a lot of light, much more than the amount of light from living in New Jersey.
Not wanting my plant to go without, I bought a grow light because it is etoiliating thanks to a lack of light. The light can be set on a timer for 4 hours, eight hours, or twelve hours. I think it's set to twelve hours but the timer seems to drift from the on-time and off-times. I'll wake up randomly in the middle of the night and spy the pinkish glow from behind my sun-blocking drapes. I've come to the conclusion that, despite my eyes being covered to minimize disturbances, my skin can tell when the light activates in the middle of the night thereby waking me up.

What I'm talking about here isn't the horseshit of dermo-optical perception, where Russian liars make kids pretend they can 'see' with their fingers, but actually detecting the presence of light. There's a paper concerning the presence of rhodopsin in the skin, a photosensitive receptor in skin cells, which detects light and precipitates the production of melanin. A more recent study 'rhymes' with the original 2011 article by its focus on opsins which the authors dub "the eyes of the skin". A similar mechanic may be at work with cryptochromes, proteins that are sensitive to blue light, but there's reason for skepticism.

Charalambos Kyriacou, an expert in biological clocks at the University of Leicester in the UK, remains cautious about ascribing a light-sensing role to cryptochromes in non-visual cells in humans. ’In humans we know that blind people do not have a body clock at all, and that all the evidence so far says that we can only sense light through our eyes,’ Kyriacou says, pointing out that in the fruit fly cryptochrome molecules in nerve cells act as light receptors while identical molecules in other tissues do not. It is possible that the light-sensing properties of the molecule are repressed depending on the cellular environment of the cryptochrome, Kyriacou suggests.

Also there's a decent article at The Conversation about the phenomenon and the biology behind the unexpected world of non-visual photoreception.

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