When you decide to spend the night in an Art suite, or another cold room, there is an orientation with good-to-know information.
The guide showed us how to get into the sheet-bag, and then the sleeping bag. Told us to dress in thin thermals, warm socks, mittens and a wool hat. They also showed the light switch and the night entrance.
At check in they gave us a small booth where we could keep all our stuff locked up.