Makeshift ways to drop temp at night?

I'm trying to get my Bodhi Dream Lotus to show its true colors, I'm 4 weeks into flowering now and wanna get on it now. I don't want to drill anymore but was hoping there are some random makeshift ways to get the temps to drop down to around 60 F at night? I thought I read something once about dry ice? idk... input/suggestions please, Trying to get my room to drop 7 or 8 degrees. I do live in a state right now where it is very cold out right now, annnnd the room I flower in is a sauna room so temp is easy to keep at a consistent temp.


Much appreciated
Turm

I have heard of people freezing 1 gallon water containers & putting those in their grow room. Maybe point a fan towards the jug.