Winter Indoor Grow Concrete floor temps

Winter has been colder this year and room temps are a lot cooler in flower room. I keep a little heater in there so I know the room itself doesn't get below 66 or 65 degrees during night periods but my girls are sitting on concrete floors. That floor has to be a lot colder than what the room temp is at night...The girls are growing like crazy so I know nothing is stunted or any issues but is cold roots something to worry about?? Let me know what you guys know or what signs having a cold growing medium "roots" does.

I use the pink 1 1/2" foamboard to set my pots on my concrete floors. too cold of roots will definitely slow your growth and concrete will suck the heat out of your pots if sat strait on it.

I don't and wouldn't put pots directly on the concrete inside. Summer or winter. I just use a scrap piece of 1/2" plywood under mine. They also sit on a low wire rack, but that's more for my benefit than theirs.
The bare floor is cooler than ambient but not by much.And it's probably fairly stable. It's just that it's a heat sink, as jarv said. Also, moisture.