my experience has been that as long as you provide a warm side - very many opinions as to what it should regulate at - i prefer 88-90 - - that the dum will be fine - i have found dums spending much time on the cool side as well - study their natural habitat - bill love travels there and you'll find that in the wild it is common for yhem to be xposed to low 70s at night even during the summer months - they will figure it out