How to Choose the Right Three-Season Sleeping Bag

If you’re cold at night, life is rough. Your sleep suffers, your mood blackens, and the fun factor of camping plummets. The good news? It’s easy to avoid this dark and chilly fate. All you need is the right sleeping bag.

THE IDEAL WARMTH 
People vary significantly in their midnight metabolisms. Do you sometimes wake up cold? Or are you more likely to wake up boiling? To help you match your personal thermometer to the right sleeping bag, most bags are rated according to the European Norm (EN) system.

This independent testing standard, which has been adopted by most major sleeping bag manufacturers, identifies two key benchmarks. A “comfort” number indicates the coldest outside temperature in which an average woman can sleep comfortably; the “lower limit” indicates the same for an average man. (Studies have shown that women, on average, run colder at night than men.) EN ratings assume you are wearing a long-underwear layer and hat while sleeping.

The EN rating is a useful guideline for choosing a sleeping bag, but keep in mind your personal assessment of how warm or cold you sleep at night. If you fall on the colder end of the spectrum, you should add anywhere from 5 to 15 degrees to your EN rating.

DOWN VERSUS SYNTHETIC 
Down weighs less than synthetic insulation, compresses to teeny-tiny proportions, and lasts for many years without losing any significant warmth. Synthetic-fill bags are more affordable and manage moisture well but are heavier, bulkier to stuff, and lose some of their loft (and warmth) after a season or two of regular use.

Down is pricier than synthetic alternatives and has gotten markedly more so in recent years as demand has soared. Down also rapidly loses its insulating value as it gets wet, although new water-resistant down has become increasingly common. Some bags even feature a water-resistant shell fabric, which offers additional protection. High-fill-power down, a measure of how puffy and warm the down is per ounce, saves a minor amount of weight for a major increase in price—primarily an option for big-spending ounce-counters.

HOW TO FIT A SLEEPING BAG
A properly fitting sleeping bag will wrap around you as snugly as possible—but not so tightly it’s uncomfortable to sleep in. For an optimal fit, most sleeping bags feature a tapered “mummy” design. There are two important size dimensions to consider with this style: length and shoulder girth. When it comes to length, opt for the shortest possible, minimizing unneeded space and weight, and maximizing warmth. The key test is this: When you get inside the sleeping bag and pull the hood snug around your head, do your feet push against the end of the bag and compress the insulation? If so, the bag is too short.

Next in importance is shoulder girth: the circumference of the sleeping bag around the shoulders. Most men’s sleeping bags feature a shoulder girth between 60 and 64 inches, though some ultralight bags run narrower. Women’s sleeping bags are usually slightly slimmer around the shoulders, generally ranging from 56 to 60 inches. The easiest way to determine your preferred shoulder girth is to get inside several sleeping bags of different dimensions.

Finally, consider the hood. A properly fitting hood will wrap comfortably and naturally around your noggin. Once cinched up, the hood should move with your head as you roll from side to side.
 
Sleep tight!
This column originally appeared in the May/June issue of AMC Outdoors
Photograph by Jens Ottoson/Shutterstock.

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