High 60's at night is actually fine for a corn snake, as long as you have a good UTH on one end of the cage with hides on warm & cool sides. Corn mostly
prefer temps about 70-73* & use UTH as needed for digestion. What are the day time temps in your room? Be careful you don't over-heat a corn snake,
they aren't like BPs at all. (I currently have 5, & have raised quite a few in previous years.) The nice thing about many colubrids is that you don't have to
be so worried about the whole cage being so warm. During the day, & only IF you need a little more warmth, use a low wattage incandescent light with a
dimmer (rheostat) control switch in an over-head dome-light fixture, but this is best for when your corn snake gets bigger since hatchlings aren't always brave
enough for branches, but as corn & many rat snakes grow, they love branches. Again, just don't over-do the heat, the area in the cage over the UTH should
not exceed 85*, & unless you live in an igloo
you want the UTH to be roughly one sixth of the cage floor.