I spoke with electrical people about turning these down at night and they all said absolutely not. Just set it and then leave it alone. it costs more to heat the unit back up on a cold morning then if you just let it run through the night. Added benefit....no cold rooms to wake up to ever again!
Even at around zero F they keep my house warm enough during the day, but the interior temp does drift down a bit when it’s colder at night. And it’s not a state of the art energy efficient house, either. Built in 1968.