My thermostat on my tank for my albinos recently broke...and until I get the money for a new one, I haven't been using the heat mat and I turn the lamp off at night. If it gets really cold...I leave the lamp on at night...but I wouldn't leave a heat mat on at night. Just make sure to watch your thermometer during the day and yes, I would shut the heat mat off at night. As long as temps don't drop too low in your house at night...you should be fine.