The majority of tree frogs in captivity are nocturnal. They don't get exposed to sunlight anyhow. This includes White's Tree Frogs. If you think just because your tree frog sleeps on a branch that receives light during the day that they do that in the wild, all the tree frogs would be dead from dessication. Anyone who has done any field work with nocturnal tree frogs can tell you that they are extremely difficult to find during the day and one place you don't look is branches exposed to sunlight.