All sleeping bag makers have great specification sheets. What these don’t tell you is the sleepability of the bag. Does the product enhance or reduce the quality of sleep? That’s sleepability. Many sleeping bags have a standardized EN rating (or European Norm warmth rating), which is something we love to see, yet the EN rating is not always true to real-world use. After all, most sleepers tend to move around in our sleep and let drafts in–or not–depending on whether the bag is well designed.
We recently set out to test 7 sleeping bags for their sleepablility and warmth in the field. Here are a few general points to keep in mind.
Insulation: Sleeping bag insulation traps warm air created by the human body. It is classically divided into two groups: down and synthetic.
Down is insulation from the under feathers of select birds, typically geese. It’s been used as insulation since 1600 and has many benefits. Down is highly compressible, allowing sleeping bags to pack smaller. It does not break down when compressed, and as a result, a down bag can last a lifetime. Ounce for ounce, high-quality down offers more insulation than synthetics. As it gets wet from rain, condensation, or humidity, however, down begins losing its loft and its ability to keep you warm. In just 80 percent relative humidity a 15-degree bag turns into a 30-degree bag. Fully saturated, it can take days to dry. Down is rated by fill power, the number represents how many cubic inches one ounce of down can fill. As the fill power goes up, so does the cost; and warm down bags can get expensive.
Synthetic insulation has two advantages over down. It still insulates while wet, some up to 80 percent of the original value. Once wet, synthetic insulation is considerably faster to dry, often just a few hours in the sun. It’s also considerably cheaper than down. On the other hand it is heavier and bulkier than all but the cheapest grades of down. Synthetic insulation breaks down each time it’s compressed into a stuff sack, but for the typical user a synthetic bag can last several years.
A recent breakthrough in insulation is various types of “drydown” which is down coated with a hydrophobic finish. It retains everything we love about traditional down but handles humidity much better. Although it stays dry longer than traditional down, it still takes much longer than synthetics to dry if saturated.
Both synthetic and down insulation do not work while compressed. Several designs take advantage of this by putting little or no insulation on the bottom of the sleeping bag, relying on the insulation of the sleeping pad for warmth. In some designs it works great; in others it makes for long nights.
Durable Water Repellent (DWR) is a coating added to fabrics at the factory to make them water-resistant. It wears off over time and reapplication at home on items with down can ruin the insulation.
EN Rating: The European Norm rating is an independent third-party temperature rating system for warmth. It measures three temperature ratings for a bag: comfort, limit, and extreme. Manufacturer’s commonly list the limit in the bag name, but if you want a good night’s sleep, pay more attention to the comfort rating.
A do-it-all bag for car camping and the occasional overnight trip, or canoe trips without portages
For those on a tight budget
Best for expeditions with lots of hiking or portaging
Not sure where your paddling will take you? This one can do it all.
Best for tall people with active legs
Best for wet conditions
Best for immobile sleepers who need the smallest-packing bag