Hi there, and welcome to the exciting, confusing, and at times down right frustrating world of keeping leopard geckos.
These are the facts to the best of my knowledge, and I hope they help you. If anyone has knowledge to the contrary, please feel free to correct me.
1) For the vast majority of the time leopard geckos have been kept in captivity, it has been thought they don't really need the UV lights because they are nocturnal (actually, crepuscular if you want to get nit-picky)
2) Relatively recently, some people have started using UV lights based on the theory that leopard geckos would be exposed to low levels of UV radiation in the evenings and mornings in the wild.
3) There is limited research out there on the subject, and many people who do use UV lights disagree on how to use them.
4) Because this is a relatively recent trend, and because the technology behind the UV bulbs is evolving, to the best of my knowledge there has not been any comparisons of the health of UV-exposed leopard geckos vs. non-UV-exposed leopard geckos over the course of their lifetime.
5) Of my three leopard geckos, each has their own tolerance for light in general. With that in mind, if I used a UV light, all three would be exposed to it for different amounts of time. How do I know which ones are getting enough and which are getting too much?
6) For many years now, leopard geckos have been successfully kept without UV lights into their late teens and even older.
Conclusion: I prefer to use a good calcium powder with D3 and forgo the UV lights until there is more sound research and methodology behind the use of UV bulbs for leopard geckos. I prefer to have something a little more substantial than a handful of hobbyist's opinions, even though they could be right.
I hope that helps, and I hope others share their thoughts. Good luck.
