Ok I suffered the same problem as you and it's pretty much solved. My room gets to around 65 at night and warms up kind of during the day. What I ended up doing was wrapping the sides and back with a blanket as a quick solution. It kept my temperatures much more stable. I suspend my lamp a little closer to the cool side and it is on 24/7. I have a 20 gallon long and the lamp is a black light 75 watt. It came with a dimmer so I adjust accordingly but most of the time it's at full power all the time. You might want to get a more accurate thermostat? That might be a "problem". I keep my hotside 87 degrees and in conjunction of the heat lamp it pretty much stays that way, but I see my thermostat really working at it to keep it like that. ALSO I would get a temperature gun. I got mine on wednesday and I have no idea what I would do without it. And cover the screen top (at least 65% of the top as hot air rises and the screen doesn't really stop the heat from escaping.

If you're handy take a look at this: http://ball-pythons.net/forums/showt...nsulating+tank

As a long term solution (which is what I am doing) Get some foam boards (or actual insulation which is what I'm doing), glue on some aquarium background and glue that onto the sides of the tank. pretty insulation! DIY: http://ball-pythons.net/forums/showt...ium+background

TL;DR: Wrap your tank in a blankie to keep the temperatures more stable. Cover at least 65% of the screen top. Keep the humidity at 50%+, as water in the air helps keep temperatures more stable as well. And take a look at both links. Hope you have as much success as I do!