Ball python heat at night

Hi guys so i got the right temps set for the day but at night my house gets really cold. In the tank abmbient gets a little under 80 and his spot under the lamp goes from 85-80. Are these temps safe at night or will he get sick? I am using 75 watt infared at night.

The min the hot can be is around 84, anything lower will affect digestion. Temporary drops to the mid seventies are no big deal but on a continuing basis you may be courting a respiratory infection and regurgitation.

The ideal temp ranges are on the BP care sheet. Hot spot should be around 90.