New to Frogs- question about terrarium temperatures

[sbaugz]

So I am new here and I am also new to frogs. Location is SE Wisconsin. I have two terrariums- one is a mini exo terra (12x12x18) that houses a single Green north american Tree Frog. The other is a small exo terra (18x18x24) that houses two juvenile Dumpy White's tree frogs.

During the daytime, I use a single heat lamp in the mini tank and two heat lamps for the small tank. The daytime temps have been around 78-85 degrees.

My question pertains to night temps. All summer long it has not been a problem. Night temps would get down to around 70-75 degrees. Now that winter is coming, my house temps are starting to drop at night. In my daughter's room, where the frogs are kept, it tends to get pretty cool at night. Its the farthest room from the furnace. This morning, I noticed the temps got down to 68 degrees. In the middle of the winter, I would not be surprised if it got to 62 degrees. I have already noticed that my green tree frog is not as active as he used to be. He tends to sleep much more and doesn't eat as much.

So, should I provide supplemental night heat? If so, how should I provide this for each of the terrariums?