not likely to be the death of the plant but the cold did spot the leafs last week. new growth is looking green and enjoying being in the main room.
2 plants under a 400 W MH . i hope now growth will take off! The Alaskan Purple i assume is more cold resistant because it has stayed green and outgrown the wedding cake.
Might be worth sticking them on a 24/0 light schedule if your budget can’t stretch for a heater during lights out mate, 60f is really going to slow growth... I usually do 18/6, but if I had heat issues, I’d do as above 👍