A dimmer?

If the temps you are reading are not correct, that could be a big reason for stress. I know all of my snakes burrow under their substrate and lay directly on the glass/plastic. Without my thermostats, the bottoms were reading well over 130*. I use a temp gun because I personally don't trust the cheap digital thermometers. From what I've read they can vary as much as 10 degrees. Also, when I was using a dimmer, I had to change the setting up to 8 times a day because it fluctuated as the day went on, so I'd be careful with that as well.