Question about lights

[Caitlin]

I started keeping snakes decades ago, and red and blue lights were the norm. Part of the fun of keeping snakes, though, is keeping up with the changes in husbandry that come about as our understanding of our snakes grows.

In addition to a group devoted to supporting new keepers, I am in a couple of reptile husbandry groups elsewhere that are fairly number-crunchy, science-based, and generally nerdy - which is just pretty much the way I am, lol. One group is focused almost entirely on lighting and reptiles and includes a wonderful veterinarian who has dedicated her entire professional life to studying reptiles' lighting needs. Without going into a big drawn out description, I will just say that I no longer use any colored lights at all, and I don't use any light-emitting heat source at night for my snakes. I use heating elements that emit heat but no light (radiant heat panels or deep heat projectors).

Why? Because for our snakes, a 60W red bulb is over 3,000 times brighter than a full moon and over 3,000,000 (yes, that is 3 million) times brighter than a cloudy night. Even a 50W "moonlight" bulb is over 800 times brighter than a full moon and almost a million times brighter than a cloudy night. Exposing snakes to light 24/7 is pretty stressful for an animal that has no eyelids. There's evidence that exposure to constant light can disrupt their natural night/day cycles, and at least preliminary evidence that lights in the blue/purple color spectrum can contribute to macular degeneration. Many thanks for the graphic below to one of my colleagues in the "New Ball Python Keepers" Facebook group.

Editing to add: I just found a great quote from Dr. Frances Baines, the veterinarian I mentioned above. I hope this information is helpful.

"Red light will NOT cause eye damage and is NOT going to make any animal blind. That is nonsense. (Red LASERS - any laser colour in fact - can blind any animal or human by burning the retina but this is a very different thing from a red lamp or LED.)HOWEVER... yes, animals CAN see red light, and yes, if it is bright enough for a human to see it as a red colour at night, it is FAR brighter than moonlight (which is less than 1 lux) because humans can't see colour under light as dim as moonlight. All nocturnal animals can see any light that is a bright, or brighter, than moonlight - and some lizards can see different colours in very dim moonlight, too. So using red lights at night is going to spoil their colour vision (everything will just be red). But perhaps more important is the effect on behaviour, of "light at night". Even dim moonlight (which is very dim white light, NOT blue!) alters the behaviour of many nocturnal animals. At least one study demonstrated this in snakes.
Having said this, it is also true that blue light is far worse than red light, if for some reason a reptile keeper wants to light his/her animals at night. The blue wavelengths around 480nm (those typically emitted by blue LEDs!) are by far the most effective for disrupting circadian rhythms (sleep-wake cycles and all other daily bodily rhythms). Just a brief exposure will re-set body clocks. These wavelengths are predominent in dawn light (that blue-purple light before sunrise) and signal the start of day; and get stronger and stronger as the sun rises, to reach maximum by mid-day. Using blue light at night is a very bad idea, physiologically. In addition, bright blue light (such as from an LED at close range) can indeed damage the retina, as those wavelengths are the worst for "bleaching" the retinal pigments. It is believed that it is blue light which, over many years, can cause blindness from macular degeneration in elderly humans, and some nasty animal experiments have proven retinal damage in small mammals from strong blue light shone into the eyes.
We worked on using extremely strongly dimmed, warm white LEDs for simulating moonlight in one zoo, with excellent results."