Forget about down sleeping bags on the Arctic Ocean. They are very light and comfortable but are unsuitable because the formation of ice particles will make the down stick together and lose its insulation ability. Fabrics made from synthetic fibers are the only option.

Synthetic fibers can handle the formation of ice inside the bag much better, but you must try to prevent that from happening. Especially on extremely cold days it is dangerous to allow sweat and moisture from the body into your sleeping bag. Insulation rates can drop dramatically.

A good solution, albeit quite uncomfortable, is to sleep inside a plastic bag or so-called vapor barrier liner. It is a very damp yet effective solution to reducing the formation of ice inside a sleeping bag.

The expedition will use a three layer system consisting of a liner that transports moisture away from the body and a liner that prevents moisture from getting in the last and most important layer, a heavily filled sleeping bag rated to -40° C. The expedition is using The North Face's "Dark Star" as its third layer.