hi
how and where are you measuring the temps hun? Ideally the thermometer and the stat probs need to be on the floor at the hot end.
I don't use lights at all in any of mine ~ statted heatmats provide all necessary warmth and as the rep-room is lit by a window and room light the geckos have a day/night cycle
hope this helps a bit ~ anything else just give me a shout
regards