Great experience, once in a lifetime!
Try to get there by at least 4pm, where you will have a guided tour of the ice hotel. The last tours are 3pm, 4pm and 5pm, so you'll have to get in for one of those.
There is then an information session for 1/2 hr to tell you the rules of how to sleep at the hotel comfortably, this is after the tour and before you sleep for the night. You must attend this as they go over how to use the sleeping bag, etc.
Really beautiful rooms and hotel. The carvings were outstanding. Really magical place! Daytime was beautiful, and when the sun went down and the coloured lights went on it was truley magical! I took hundreds of pictures!
I'm usually cold, so I chose to sleep in in a wool turtleneck top and wool long johns (light merano wool) and a second layer of thick fuzzy acrylic top and bottoms. I also slept in thick wool socks. I was comfy and warm all the night (after sitting in a hot tub first, to increase body temp, as is recommeded).
Once in sleeping bag, it was hard to get comfy. You're in a "mummy sleeping bag", so you can't move around too much. I finally settled on my back.
First thing I noticed that although my body was toasty, my face and nose got very very cold. Your face is completely exposed to the cold air. I eventually put a glove over my nose/mouth to keep it warm. You're not supposed to breath into your sleeping bag (it'll get humid inside, which will make you become cold), so have something to be able to lightly put over your nose as I heard many people complain of freezing cold noses. If I had known, I would have brought a scarf or a face mask of some kind because it was really uncomfortable. My throat began to hurt as well, from the cold. Now, a few days later, my throat still hurts and is feeling infected. So bring something for your face and mouth, to shield you from the cold.
I had a fireplace in my suite, but it was a waste of money. The fire is only on for a short time, and you're really not spending time in your room until it's bedtime (there are activities from 9-10:30pm in the bar). So after the activities, most people would take a hot tub and then go to their rooms by about 11 or 11:30. Well, by that time the fire is out anyway, as it burns really quick.
Just before I went into the hot tub, I discovered my fire had gone out and I hadn't really enjoyed it yet, so I went to the desk to ask for more firewood and they said they'd set it up for me. Once I was in my pjs, I found my fire hadn't been re-lit. So I saw my fireplace lit for a total of about 5 mins (was beautiful when lit however!). So don't bother with the fireplace, everyone gets candles which are lovely too. They charge quite a bit more for the fireplace, and you don't get anything for the extra money you've spent.
I had a hard time falling asleep, but remained warm (my body, anyway). When I woke up at about 6:30 and went to the Celcius lounge, I discovered 2 people sleeping on chairs - they didn't make it through the night. I'm not sure of how many end up leaving during the night.
Great experience! Would I do it again, no - but I am glad I did it once!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.