hi simon!
I don't heat any herp at night, no matter what time of year. IMO it may cause a variety of problems... I'm in Sydney btw, and the room is usually on the warm side, doesn't get below about 12 degrees on the coldest winter night and warms up well during the day. I blast my pythons during the day and freeze them at night, feed only for 5 - 6 months of the year.