Thank you for your question. The recommended night temperature for your tortoise would be 60-65 degrees. We do recommend using a thermometer in the enclosure to monitor the temperature. You may use a night heat bulb to increase the temperature at night, if necessary. Below, we have included a link to this bulb.http://www.drsfostersmith.com/produ...
In nature, your tortoise would hibernate during the relatively mild winter months of their natural climate. During this time, the breathing and heart rate drop notably. However, it is important the ambient temperature does not fall below zero. Therefore, many domestic animals are kept in the basement in a roomy, rodent proof box with a thick layer of dry leaves. The temperature should be around 5 degrees Celcius or 41 degrees Fahrenheit.