There are three factors to consider when choosing a sleeping bag: warmth, sleep style, and activity. We recommend choosing a bag that is warm enough to handle the most extreme colds you expect to encounter, as it is always a safer bet to unzip a bag than to pile on extra clothing. Next is sleep style. Back sleepers may appreciate the profile of a mummy bag, while side sleepers would fare better with a quilt. Finally, if you are planning a backpacking trip, carefully consider the tradeoffs of weight and packed size before purchasing a sleeping bag.