Ultraviolet light - your lizard needs it for communicating..... don't keep it in the dark

RobinSings. https://en.wikipedia.org/wiki/Puerto_Rican_crested_anole

Lizards can see colours that we see and they can see colours we don't see - the colours in ultraviolet light. And colours matter to them, because they communicate with each other using colour signals. If they couldn't see ultra violet colour, it would like being colour blind for a human. And worse, because where we use words, they use colour to "speak."
Anoline lizards, arboreal American lizards, use their dewlaps to communicate.  They open and close them, making a sort of colour flash, rather like (but not very like) light signals used in morse code from ships. The brightness of the colours and how they stand out from the background makes them effective signals. Male lizards sit up on a high perch or branch, and flash their dewlaps to attract females and deter male rivals from a distance. Dewlaps are coloured differently in different species, probably to make sure that they show up in different habitats.
The females and rival males "capture" the signals with their eyes which have special cones. One type of cone is specialised for ultraviolet light. (Humans don't have this kind of cone.) Scientists tested Puerto Rican crested anoles to see what happened if there was no ultraviolet light visible. The lack of ultraviolet meant that the signal looked less bright to the lizard. The signal (which simulated a dewlap flash) just looked dark against the background.
Moreover, ultraviolet light helped the lizard detect motion. A dewlap flash is only a flash if it stops and starts, so detecting motion is important. Detecting motion in all animals, including humans, seems to depend on the contrast between signal and background which is more noticeable for a lizard sees the ultraviolet light.
So if we are keeping lizards in vivariums with no ultraviolet light - or where the UV lighting has failed - we are keeping them in the dark. Not only are they not getting the UV light they need for vitamin D (which means low immune system and poor bones), but they are living in a dull dark world where they cannot communicate properly.

For more read:  Fleishman, L. JJ. & Persons, M., (2001), 'The influence of stimulus and background colour on visisbility in the lizard, Anolis cristatellus, The Journal of Experimental Biology, 204l 1559-1575