From what I've learned from people that I respect, it is the night cooling that can lead to RI's. Because of the bounce from warm to cold every day, it puts stress on the snakes and can result in respiratory infections. If you lower the temps and leave them there, it doesn't pose the same problem. I do not night drop, but lower the ambient temps a few degrees and the warm spot a few degrees. They go down and stay down until I'm ready to warm them back up.