Crawling into a sleeping bag that you know is going to be warm and comfortable is one of the singular pleasures of any camping adventure. Just as a good sleeping bag can make for a good night's sleep, an ill-suited one can spell discomfort or worse.
Decide where and when you're likely to use a bag. This will help determine if you need a winter, 3-season, or summer bag. Compare each bag's individual temperature rating. Ratings give a general idea of insulating performance and are a useful point of comparison. We believe our temperature ratings are realistic for most people in most conditions. Choose a warmer bag if you tend to sleep cold.
DOWN FILL vs. SYNTHETIC FILL
Synthetic insulations (like Primaloft, Climashield, and the plethora of proprietary insulations) are a safer choice if you often find yourself in wet conditions, such as backpacking Washington’s Olympic coast with a tarp for shelter, like I did a few years back. I was very grateful for my synthetic bag on that trip because synthetics don’t completely crap out on you when they get wet. Although they won’t exactly keep you toasty, wet synthetic bags are not totally useless. Wet feathers are. Until you get them dry, of course.
Many people prefer down sleeping bags. And it’s not just the weight, a high quality down bag can be over a pound lighter than a synthetic with the same temperature rating–it’s the cozy factor. I always sleep warmer, and warm up quicker, in a down bag. And now that you can get awesome waterproof stuffsacks–such as Sea to Summit’s eVent Compression Dry Sacks (Editors’ Choice Award winner in 2007) you at least won’t have to worry about your down bag getting wet in transit.
DOWN FILL SLEEPING BAGS
Down is one of nature's finest insulators. Nothing matches its warmth for weight, compressible allowance, and resilience. Its ability to absorb perspiration and cozily drape along the contours of your body are unparalleled by synthetic materials.
Down consists of thousands of plumules, fluffy filaments that line the underside of waterfowl feathers. All down fills also contain some feathers and feather fibres.
Many manufacturers use both duck and goose down in the construction of down sleeping bags. The quality of down doesn't depend on the bird species it comes from, but on the bird's environment and maturity. Birds respond to colder, wetter conditions by growing fluffier, warmer down. White or grey down has the same performance. For purely cosmetic reasons white is more expensive than grey. It can be used in light weave or translucent fabrics without showing through.
Fill-power (or loft power) is a measure of fluffiness. It is expressed as the number of cubic inches an ounce of down displaces. Fill-power of 500 to 550 is mediocre, 600 to 700 good, and 750 to 850 excellent. Higher fill-power articles provide more warmth for the same weight.
Down is more expensive than other insulating materials. However, when you divide its cost by the number of cozy nights it provides, down is a bargain. A down bag costs approximately 50 percent more than a synthetic bag of the same temperature rating, but down insulation lasts about three to five times longer.
When it gets wet, down insulation is compromised. In damp conditions, a waterproof-breathable shell fabric can protect sleeping bags or jackets from external wetness. In cold climates, a vapour barrier sleeping bag liner keeps internal moisture out of the down fill. In consistently wet conditions, it can be very difficult to keep down dry, in these circumstances, a synthetic fill may be the best option.
Down sleeping bags and outerwear require maintenance to perform at an optimum level. For tips on airing, cleaning, and storing down items, consult the care instructions that were provided by the manufacturer of your particular down filled item.
SYNTHETIC FILL SLEEPING BAGS
Synthetic fill sleeping bags are a viable, sometimes preferable, alternative to down bags. They are non-allergenic, have a lower initial cost, and unlike down, they provide some warmth when wet. Synthetic fills vary in weight and how much the fibres can be compressed during packing. Generally, the more durable a synthetic insulation is, the heavier and bulkier it will be.
Synthetic insulation is made up of plastic threads that are either continuous long filaments or short staples (pieces about five centimeters long). Short staples may be a mixture of thin and thick pieces. Thinner, lighter threads fill voids and trap warm air effectively, while thicker strands provide loft and durability.
Various methods are used to keep synthetic fibres from clumping or settling. The least expensive (the only method used with continuous filaments) is to bond fibres in place with a sprayed-on resin. The resulting blankets, or “batts,” are durable, but rather unyielding. Hence, resin-bonded fibres are less soft to the touch.
A more expensive method (used only with short staples) is to mix special fibres among thin and thick staples. The blend is heated, causing the surfaces of the special fibres to partially melt, and fusing all the fibres into a three-dimensional matrix. This yields a softer, more down-like feel. Premium short staple synthetics are stabilized with both heat bonding and resin, providing a good balance of form-fitting softness and durability.
FEATURES AND CONSTRUCTION
HOOD & NECK YOKE
You lose 30 to 50 percent of your heat through your head and neck. A well-patterned hood is roomy yet contoured, and significantly increases a bag's warmth without adding much weight. The neck yoke is an insulated collar that covers your throat and shoulders. It reduces heat loss whether the bag is snugged down or loosely zipped. Some bags have a neck and muff combination that completely encircles the neck for additional warmth.
FOOT-BOX & FOOT OVAL
Feet and toes crush insulation. To compensate, mummy bags have square-shaped foot-boxes that allow for natural foot positions. The less-tailored equivalent in a barrel bag is called a foot oval. Extra insulation at the peak of the foot-box or foot oval helps warm your toes.
ZIPPER & DRAFT TUBE
Lefties generally prefer right-hand opening bags and vice versa. If you are planning to zip two bags together, ensure one has a right zip and one has a left zip. An insulated tube that runs behind the zipper to prevent heat loss is called a draft tube. Ideally, it is sewn only to the lining material, since sewing through the bag creates a cold spot.
THE SHAPE OF YOUR SLEEPING BAG MATTERS
A sleeping bag's shape can dramatically affect its performance. It will also impact how comfortable it is to sleep in and how small its packed size will be.
Mummy bags are designed to save weight and maximize heat retention. They narrow at the feet, flare out at the shoulders, then taper to a fitted hood. With less space for your body to heat, a close-fitting bag has superior warmth to weight than a roomier bag. However, some people find them too constricting.
Barrel bags trade thermal efficiency for extra room. They have no hood, are slightly tapered, and incorporate a patterned oval foot section. They are slightly heavier and bulkier than mummy bags.
Rectangular bags are suitable for warm weather, and are not the best choice for most back-country travelers. Although inexpensive and roomy, they let a lot of body heat escape and are heavy and bulky for the insulation they provide.