temperature control during light off period (noobie question lol)

so i started a mother room for the first time lol, iv got everything set up my plants about 8 inch"S from light (400 HPS) my day temp is around 72-76 degrees F. Now during the light off period my temp goes down to 65-69 is this bad for my plants? is two cold during the light off peroid?

P.s. the reason for the temperature fluctuation is because i have a wood stove heating my house

72 to 76 is good for day temp. Don't let it fall anymore than about 7 degrees at lights off. Good luck