Personally I don't think gliders benefit from sun in the sense of vitamins, as they are nocturnal. So even though mine are in a naturally well lit room suring the day, they are still hidden away in a pouch, so they won't come into contact with the sun in that sense.
BUT, I think it is important for them to have access to 'natural' light in the room as it does regulate their sleeping patterns. I'm not sure a lightbulb would substitute x