Much like your bed at home, your sleeping bag is a place where you will be spending about one-third of your time in a 24-hour period. Making sure that your sleeping bag is comfortable, warm, and appropriate for the conditions is essential for getting a quality night’s rest so you can wake up the next day ready to crank out some miles, summit a peak, or simply soak up the natural scenery without dozing off. The good news is that there are plenty of options for high-quality sleeping bags, so finding one that works for the conditions you most often backpack in is an accomplishable task. The not-so-good news is that finding the right bag can require a significant amount of research and a sleeping bag will likely be one of the more expensive single items you buy for backpacking.

Quilts provide the same function as a sleeping bag – keeping you warm while you sleep – and many in the ultralight backpacking community favor them over sleeping bags for the weight savings. Since sleeping bags are still the most common choice for backpackers, this article will focus on them and leave an overview of quilts for another day (or night, more appropriately). Before going any further, it must be noted that a sleeping bag is only as good as the sleeping pad it is used with and the shelter or tent it is used in. Detailed discussion of sleeping pads and shelters surpasses the scope of this article by a country mile, but guides to each of those can be found at the previous two links.

Temperature Ratings

One additional caveat worth noting before delving into the topic is that, depending on where you do most of your backpacking and if you backpack year-round or not, you’ll probably end up needing at least two sleeping bags to meet the different conditions you’ll face. If you engage in subzero winter camping or mountaineering, that number is likely to grow. But, for most of us, a bag for summer conditions (30-40 degrees F, although in the Southeast a 50 degree back would be adequate) and a bag for shoulder-season and/or mild winter conditions (0-15 degrees F) are sufficient.

Figuring out which temperature rating to get a bag for can be a bit challenging. No one wants to sleep cold, so novice backpackers often get a bag warmer than they need to and end up carrying around the extra weight in their pack for no real benefit. They often end up uncomfortably warm at night, with the bag unzipped and laying over them like a blanket. When buying a sleeping bag, don’t purchase with the idea that you might get into subzero camping at some point in the future, even though you don’t own any of the other appropriate gear (four-season tent, winter down jacket, etc.). Instead, purchase for what will be the most common conditions you expect to experience. The majority of sleeping bags sold today have a standardized system (called EN or ISO, based on when the bag was tested, but they are virtually identical) for determining what temperatures they perform in. This allows you to compare apples-to-apples when looking at bags. This information should be on the tag of the sleeping bag or listed online in the specifications.

So, if you do most of your backpacking between March and November in Great Smoky Mountains National Park or other areas of the southeast, a 20-30 degree bag would be most appropriate, although near record-breaking cold snaps or camping at high elevations might skew the functionality a bit for the months on either end of that range. And even then, a 20-30 degree bag might be a bit warm in the summer but is about the closest you would get to a single-bag-that-does-it-all given the parameters. A bag in that range would also be appropriate for backpacking in the cruelly short summer backpacking season in Western mountain ranges such as the Sierras, Rockies, and Cascades.

Down vs. Synthetic Sleeping Bags

Choosing between a down sleeping bag or a synthetic insulated bag is another bridge to cross. Down has a better warmth-to-weight ratio, compresses better, and lasts longer. Its kryptonite, however, is moisture. Down loses its ability to insulate when wet, so if you backpack in particularly humid environments for days on end with no opportunity to dry out your gear, you might consider synthetics. That said, it is fairly easy to keep a down bag from getting wet and advances in shell fabrics and hydrophobic treatments for down over the years have helped mitigate this issue. Sleeping bags using synthetic insulation are usually less expensive, slightly heavier (although innovations in synthetic fabrics have narrowed the gap considerably), and not as compressible. They maintain some of their insulating ability when wet, but you’ll of course be uncomfortable in a wet sleeping bag, and if you sleeping bag is wet, chances are high that mistakes were made along the way.

Construction

Most sleeping bags for backpacking are mummy bags, which increase thermal efficiency by covering the head and shoulders and allowing for the bag to be zipped up and cinched down with your face exposed to breathe (do not burrow down and breathe into a sleeping bag, as the moisture you release will be trapped in the bag) but otherwise completely enclosing you in the bag. This can feel a bit claustrophobic at first, but comforting once you’re used to it. If you can’t get used to it, then a quilt is an option to look into. Some mummy bags are cut very slim to minimize weight and maximize efficiency and others are roomier. It will take getting inside the bag and tossing and turning a bit to figure out which is best for you. Sleeping bags are also designed slightly differently for men and women, owing to differences in body shape.

Other features that you will want to be aware of are a draft tube that runs the length of the zipper to block out cold air from coming in through the zipper and a draft collar that, much like it sounds, goes around your shoulders when you're in the bag to block out cold drafts and prevent heat from escaping. I've found that having a quality zipper can make or break a sleeping bag. There are few things more frustrating than having to go to the bathroom in the middle of the night and fighting with a finicky zipper that snags on the fabric and gets stuck. Sleeping bags will have the zipper either on the left or right hand side of your bag, sometimes you have a choice in this and sometimes you don't. If you do have a choice, most people choose so that their dominant hand will be the one doing the zipping (so a right-handed person would choose a bag with the zipper on the left side when you're lying down). Another consideration, if you often backpack with a significant other, is getting bags that can zip together. I've found that there is a fairly wide range of cross-compatibility with this. I've had a Feathered Friends left-zip bag zipped together to a right-hand zip Mountain Hardwear bag, creating one big sleeping bag to get cozy in.

Most of the sleeping bags marketed towards backpackers use a lightweight shell fabric treated with DWR to provide some moisture resistance. Pertex is one of the most common brands used. Some bags, like the Apache from Western Mountaineering, are available using GORE Windstopper which provides more weather resistance than most bags. For most people using their bags in tents and in three-season conditions, the lightweight shell fabrics are sufficient.

Packing

It goes without saying that the actual performance of the sleeping bag is the most important part in choosing a bag, but the transportation and storage of a sleeping bag deserves consideration as well. I haven't found a better option than the Sea to Summit eVent Compression Dry Sack. Although the weight of this compression sack is not negligible, even for the smaller volume models, it is exceedingly durable, drastically decreases the volume in your pack the sleeping bag takes up, and is completely waterproof when properly closed. For those using a down bag, this provides a peace of mind when hiking in rainy conditions or on trips with multiple river fords that is worth every ounce. Other options include storing your bag in a waterproof roll-top dry bag and / or a trash compactor bag. Most sleeping bags come with stuff sacks, but these typically don't allow the bag to be compressed to its minimum volume. The stuff sacks provided by the manufacturers are more useful for socks and other pieces of clothing, in my experience. Many sleeping bags also come with large mesh storage sacks to store your sleeping bag when not in use. These are very useful, as your sleeping bag should not be stored in any state of compression when not in use. This can damage the insulating material, reducing loft and ultimately the warmth of the bag.

Generally speaking, you can expect to spend anywhere from $150 to $500 on a quality sleeping bag, and this can definitely be a situation where you generally get what you pay for: investing in a good bag will get the most important job done – keeping you warm at night – while saving the most weight and taking up less space in your pack during the day. Considering that a sleeping bag is one of the heaviest things we normally carry (offering a great opportunity to save the most weight), and combined with the longevity (especially with down bags) that we can expect from a properly taken care of bag, this is one gear category where an upfront investment can pay off over time.

For a list of sleeping bags that you can sort and filter by all the points discussed in this article, take a look at this page at REI.