Sleep studies reveal that most of us shift positions throughout the night, ultimately spending more time on our side than in any other position. But even if you're not one of those people, the Disco 30's side-sleeping-friendly design just so happens to make it way lighter than it should be for how roomy it feels.

The bag's spoon shape adds room near the elbows and knees for comfortable shifting while keeping the bag super-packable, and it's a big reason why it nabs our best overall spot. An REI backpacking specialist in Plano, Texas, who also works as one of the co-op's virtual outfitters, is a big fan: "This bag is light and accommodating of all types of sleep positions. I'm a side sleeper and I'm obsessed with this bag." One customer reviewer agrees: "I LOVE the cut of this bag... and its softness and warmth make me look forward to getting into it each night."

The big difference between the NEMO Disco 30 and its side-sleeper cousin below (the Forte 20) lies in the insulation. The Forte has a synthetic fill, while the Disco uses 650 fill-power down to keep weight low in a bag that's so generously cut. A PFC-free water-repellent treatment on the down helps it maintain insulating efficiency in wet conditions.

If you occasionally slide down to the foot of your tent at night, or your shelter is simply a snug fit, you may appreciate another NEMO touch. They made the footbox of the shell fully waterproof to prevent interior condensation from sneaking into your bag. If, on the other hand, balmy conditions threaten to make things too toasty, there's a solution for that, too: A pair of slits called Thermo Gills™ can be zipped open to cool things down. Buy here.

Versions: Women's regular and long, men's regular and long

The most affordable bag in our test, the REI Co-op Trailbreak 20 is suited well for chilly nights with a lower limit of 18°F and 5°F (for the men's and women's, respectively) and a narrow mummy cut. (The smaller the space, the easier it is for your body to warm up the bag. Read more below.) It also has a three-panel hood with double drawcords to create a snug fit and boost warmth, plus a plush draft tube, or insulation that runs along the zipper to help prevent cold from sneaking in—both features more typical of backpacking and mountaineering bags. We didn't notice any cold spots, even on evenings below 35°F. "I actually had to use the Trailbreak 20 as a quilt one evening because I was too warm," our Washington tester said after a night that dipped into the 40s.

Synthetic insulation and polyester shell that's treated with a durable water repellent make this sleeping bag a decidedly good choice for damp conditions. "Condensation was dripping inside the tent and onto the sleeping bag, but I stayed dry and cozy," our tester said after a rainy night in Washington's Colville National Forest.

Bulk is a consideration, though: "If you piled six Nalgene bottles together, this bag would still be larger," noted one tester. Our crew also struggled with a snagging zipper, reporting that users must pull the bag taut in order for the zipper to properly slide. But still, at this price point, the Trailbreak 20 is an awesome deal. Buy here.

The updated Cat's Meow 20 Eco hasn't been out long, so consider this a sort of preseason pick. That said, The North Face Cat's Meow has been an outstanding synthetic bag for more than 40 years. And our backpacking expert is confident this latest version will uphold the family tradition.

"Cat's Meow was my first-ever backpacking sleeping bag. They've updated it multiple times over the years and it's still a solid bag," says our expert, who is both an REI virtual outfitter and Portland, Oregon, store sales specialist. "I love it. It's always been at the lighter end of the synthetic bag spectrum, and that's still true today."

Past performance is not always a guarantee of future results, but one might reasonably expect good things from the 2022 edition, especially because The North Face isn't making any radical changes with the proven design.

Nice touches abound, including shockcords on the underside for attaching the bag to a sleeping pad so you stay in place. There are also more recycled materials in both the synthetic insulation and the nylon shell.

The bag's size range (regular, long and extra long) also makes it a good fit for more people—the men's extra-long can accommodate up to a 7-foot backpacker. The only scrunching down extra-tall folks need to do with this bag is when they stash it inside the included compression stuff sack. Buy here.

Versions: Women's regular and long; men's regular, long and X-long

The REI Co-op Magma lineup (these 15° bags and the 30° Magmas below) might be the most beloved sleep sacks we've ever made. You'd be hard-pressed to find a gear expert at the co-op who doesn't get just a little misty-eyed over a Magma bag.

As our experts contemplated the best down bag, their criteria became self-evident: It's all about the quality of the down, and few bags can top the Magma's 850-fill-power rating. The result is lofty warmth in a bag that weighs relatively little considering its 17° comfort rating. A water-resistant treatment on the down helps keep you toasty even in damp conditions.

Our gear editor's take: "I use my women's Magma 15 when winter camping or generally heat-hogging year-round. It makes it into my pack every trip."

Other nice touches on the Magma include a roomy footbox, a cozy draft collar at the top of the bag, an antisnag zipper and differentiated drawcords that let you discern the neck from the hood drawcord by feel. Buy here.

Versions: Women's regular and long, men's regular and long

Side sleeping in a mummy bag always presents a dilemma. Do you attempt to roll both body and bag simultaneously? Or, do you pull arms and legs into a tight fetal position as you attempt to pivot sideways inside of it? Both methods work OK, but NEMO came up with a third and, in our opinion, better option. Thanks to added room at the elbows and knees, the Forte lets you casually rotate those joints sideways without bringing the whole bag with you. Simple.

The spoon shape might look a little odd at first, but it works beautifully. "Once someone is in this bag, they're buying it," says our Farmington, Utah, REI camping specialist. It's also worth noting that the Forte's hood articulation and oblong opening are conducive to side sleeping because they help preserve breathing space after you roll.

The warming and cooling systems in this bag are also unique. Insulated with PrimaLoft® RISE—an incredibly lightweight and efficient synthetic fill that's made from 80 percent postconsumer content—the women's bag is rated for warmth down to 20°F, yet weighs just a little over 3 pounds. The "cooling" comes from Thermo Gills™ vents on top, which dump excess heat efficiently when temps start to rise. Cherry on top: The Forte includes a pillow pocket that lets you stuff clothing inside to create a dreamy perch for your noggin. Buy here.

Versions: Women's regular and long, men's regular and long

The entire Magma lineup is featured in our picks primarily because we couldn't figure out which one not to include. Our camping specialist at the REI store in Colorado Springs, Colorado, puts it this way: "When I'm talking to customers, I tell them that the Magma is the best sleeping bag REI sells. Period. That's based both on the bag's specs and my personal experience."

With a total bag weight of under 1-½ pounds, the men's Magma 30 is the logical ultralight sleeping bag pick. It features the same ultrawarm, water-resistant 850-fill-power that you'll find in all REI Magma bags. The gossamer Pertex® nylon shell, tightly woven to keep down plumules from slipping through, also helps reduce weight.

We'd be remiss not to point out that "ultralight" is one of the more contentious labels in outdoor gear. Minimalism purists adopt all sorts of strategies to shed ounces. An REI backpacking specialist in Knoxville, Tennessee, who also works as an REI virtual outfitter, offered this alternative: "If the weather is going to be perfect, my best ultralight sleeping bag is my sleeping bag liner (Sea to Summit Thermolite Reactor), which weighs just 8 ounces." That said, any ultralight fan will appreciate that the Magma 30 packs down to the size of a loaf of bread. Buy here.

Versions: Women's regular and long, men's regular and long

Our virtual outfitter in the Plano, Texas, REI store explains her cold-weather pick this way: "This bag is right around 3 pounds—and other cold-weather bags are simply a lot heavier." Our Knoxville virtual outfitter agrees: "A lightweight bag that takes you down to zero degrees? That's a great option." (The EN lower limit of the men's bag is exactly 0°.)

The Ascent's 750 fill-power down insulation is key to delivering that degree of warmth at such a low weight. Sea to Summit further added its UltraDry water-repellent polymer treatment to the fill because risking dampness in your down insulation isn't something to be trifled with when conditions are bitterly cold. "Down water-treatment tech has come a long way, too," reports our virtual outfitter, so you can be confident using this bag in moist conditions.

Customers also love the bag's dual zips (one on each side), plus another zip in the footbox. As one customer reviewer put it, "Multiple zippers prevent mummy-bag claustrophobia and provide enough ventilation options to make this suitable for all four seasons." It's perhaps more accurate to call the bag a "relaxed mummy," so it's also roomier than a typical cold weather bag to begin with. Buy here.

Versions: Regular, long

In general, you're either a quilt person or you aren't. There aren't many fence-sitters on this issue. Quilt proponents tend to be ultralight hikers or hammock campers who like its simplicity—no hood, zippers or insulated bottoms often found in mummy bags—while quilt detractors worry that they won't be able to stay warm without having a full sleeping bag.

The Magma Trail Quilt's design may convince members of both camps, cleverly helping retain more warmth and a slightly more secure feel. Instead of having four distinct corners like a comforter, it has an enclosed, sleeping-bag-like footbox. The two top corners can then be unfurled like a standard quilt or cinched around you on colder nights. You can also attach the quilt to your sleeping pad with cords that keep you centered while still allowing some ventilation adjustments.

If you compare the Magma Quilt to sleeping bags in this temperature range, it's worth noting that the 30°F estimate was determined solely by the REI Co-op Testing and Concept Lab because there's no industry standard test for quilts, as there is with sleeping bags. The 850-fill-power water-resistant down insulation, though, is the exact same ultra-efficient stuff that's in all of REI Co-op's Magma sleeping bags. Buy here.

Versions: Short, regular and long

Buying a single bag for both camping and backpacking makes perfect sense when it's a kids' sleeping bag. A child's preference for camping over backpacking—or vice versa—isn't fully formed yet. They're also going to outgrow any gear you buy in a few years. REI Co-op's venerated Kindercone backpacking bag is the perfect answer—it comes with built-in growth-spurt insurance. The included stuff sack, which is attached to the bottom of the bag so you won't lose it, can be cinched to make the bag shorter when your child is younger; as your child grows, simply move the cinch point down to lengthen the bag.

Kindercone, which in various iterations has been in the REI Co-op bag line for more than two decades, has just the right mix of toughness and tech required in a kid's bag. The sturdy shell and two-way anti-snag coil zipper resist rough use, while its polyester materials offer resistance to spills and drizzle. The Kindercone is estimated to provide warmth down to 25°F, which should help kids stay comfortable, even on a cool-weather trip. Sarah Miller, a sales manager at the REI store in Marina, California, points out that the bag's mummy-bag shape—one of it obvious backpacking features— is key here: "The slim shape isn't merely a backpacking advantage, it's also a warmth advantage because a kids' small body doesn't have to work so hard to heat the bag up."

Because the sleekly built Kindercone tips the scales at just a hair over 3 pounds, budding backpackers should also be able to carry their bag—just like their adult trip leaders.

Even the material choices in the Kindercone consider your child's future. Both the shell and lining are recycled polyester that's certified to meet bluesign® criteria. Buy here.