TBH 77 as a coolside temp i dont belive is bad, during winter, mine dropes to bout 75-76, and i keep himdity down so no RI's 2 years not 1 issue yet, and at night i do notice them hugging cool side (right now at 77-79 give or take depending on how hot day is) and again never had 1 issue with snakes becoming ill "knock on wood" There huge debates on snakes actually liking it a little bit cooler then 90, a breeder i know keeps his hot spot at 86 with cool side 75-78 and hes never had a issue(and thats not a temp drop hes keeps them steady 24/7)