Choosing a Sleeping Bag

If you are taking clients into the bush overnight one of the types of equipment you will need is sleeping bags. Choosing a sleeping bag is a surprisingly complex process because of the number of factors involved, as you will see in the article below. (Note too that recent exams asked a question about sleeping bags.)

“Choosing a “Camping” Versus “Hiking” Sleeping Bag

In general you choose a sleeping bag on the basis of the type of event you are likely to be using it for – for camping at a fixed base versus hiking or canoeing and then using it at a night-time camp. Since weight is critical when a person is carrying everything on they need on their back, a hiking sleeping bag differs from a camping bag in that it is:

• More lightweight;
• Capable of being packed down into a smaller space;
• More efficient, providing more warmth for the weight.

A camping sleeping bag tends to be more roomy and geared towards comfort and can afford to be heavier.

Choosing a Sleeping Bag’s Temperature Rating

A sleeping bag’s temperature rating tells you the lowest temperature that the bag is intended to keep the average person warm. For example, a 35° bag will keep you warm down to around 35° but below that temperature you will start to feel uncomfortably cold.

It is important to understand that these ratings assume that you are using a sleeping pad for insulation and are wearing long underwear and some sort of head covering.

Since 2009 many sleeping-bag manufacturers have adopted the European Norm (EN) testing methodology. There are four general categories.

Note: Testing reveals that women are colder when they sleep than men – and this should affect the temperature rating they should look for in a sleeping bag.

Give thought to the climate where you might have to bug out and choose a bag that would accommodate the lower temperatures you might encounter in that area. If it gets very cold you can, of course, wear more clothes inside the sleeping bag, but then you do not want a snug-fit bag (see the Shape section below). If you get too hot you can open the sleeping bag zip for ventilation.

Choosing a Shape

Sleeping bags come in four main shapes – though there are some recent variations you could look into.

Sleeping bag shape affects both weight and warmth. A close-fitting sleeping bag is lighter and holds your radiated body warmth closer to the body so is effectively warmer.

• Rectangular – this is the traditional camping sleeping bag which maximizes space for the spreading of your limbs. Often it can be completely unzipped so that it becomes a comforter or quilt. It can come in a double size or two singles can be spread out and zipped together to become a double.
• Mummy– has a slim cut for reduced weight with maximized warmth. Because of the snug fit you roll over with the bag, not inside the bag. Depending on your body shape, these narrow bags may be restrictive and uncomfortable, especially if you are wearing several layers of clothing for cold conditions.
• Barrel or semi-rectangular – the compromise shape between the above two and for warmth, lightness and roominess.

Choosing the Filling – Down or Synthetic

Sleeping bags use an insulation material to trap the warmth your body generates inside the bag as you sleep. This insulation material is either down or synthetic. Down sleeping bags are stuffed with the fine under-feathers from ducks or geese. Synthetic sleeping bags are filled with man-made insulation, mostly poly-fibers.

These materials each have advantages and disadvantages – see below for a comparison table.

A note about ethical down: Most down is a by-product of the meat industry, so bag makers have taken steps to ensure humane treatment of the ducks and geese that provide down: RDS (Responsible Down Standard) and TDS ( Traceable Down Standard) are two designations to look for.

Water-resistant down insulation

To combat down’s loss of insulating efficiency when wet, most sleeping bags are filled with down that has a water-repellent treatment.

Choosing Bag Weight (Already Determined by Other Choices)

Returning to the choice between a hiking sleeping bag or a camping sleeping bag, if you have decided that minimum weight and volume is what you need in a emergency sleeping bag then you will have chosen a down-filled sleeping bag in a mummy shape because it will be carried on your back but you still want the necessary warmth and comfort. Because a bag requires more insulation to get a warmer (lower) temperature rating, you should always compare bags of similar temperature ratings when comparing bag weights.

Choosing Construction

1. Baffles

A sleeping bag’s baffles are the chambers that contain the bag’s insulation and stop it from moving around and leaving you with cold spots of little filling between you and the outside world.  A great deal of design ingenuity goes into the distribution of the insulation between the bag’s liner and outer shell. Synthetic-filled bags typically use quilted, offset quilted and/or shingled constructions. Baffles, however, are particularly important with down bags. There are many different configurations but the two most common types are vertical and horizontal baffles.

• Vertical Baffles

Vertical baffles are great for sleeping bags that have more sculpted shapes and are generally more comfortable than those from horizontally-baffled sleeping bags, particularly for people who sleep on their backs. The disadvantage of vertical baffles is that they need mesh walls sewn along their length to prevent their down filling from migrating, so they are heavier than a horizontally-baffled sleeping bag of the same temperature rating and quality. Their advantage, on the other hand, is that they allow you to shake the down to the foot of the bag if the temperatures are higher.

• Horizontal Baffles

Sleeping bags with horizontal baffles are warmer by weight than vertically-baffled sleeping bags. If you want a truly versatile sleeping bag, look for one with continuous horizontal baffles wrapping around the entire circumference of the sleeping bag. This means that you can move your down insulation around as you see fit. Too cold? Shake all the down out from the bottom of the bag so there’s twice as much on top. Too warm? Shake it out from the top so all the down is beneath you.

2. Shell

The “shell” of a sleeping bag is the outer layer of fabric which is made of either a durable rip-stop polyester or nylon. Some are treated with a durable water repellent (DWR) coating to prevent moisture from soaking through and dampening the fill, which is usually enough to deal with light condensation.

The more expensive your sleeping bag is, the lighter and thinner this nylon fabric will be. The specification you will want to look for to quantify this is “denier”. The weight difference per square yard between a 10D and a 40D nylon fabric (the ‘D’ standing for denier) is significant, and ultra-light sleeping bags are often so thin that you can actually see right through the fabric to the down inside.

3. Inner Lining

Fine nylon or polyester are the most common materials used for lining sleeping bags and often have a brushed texture for added softness. Sleeping bags for recreational camping will sometimes use more “old-fashioned” fabrics (such as flannel or cotton), and this can be particularly cozy in lower temperatures. Cotton traps moisture, however, and for camping in warm or damp weather, nylon will remain cooler and dry faster.

Choosing a Sleeping Bag Size or Fit

Sleeping bags are sized by their length.  The correct length for your bag should correlate directly with your height. If your sleeping bag is too short, your feet and head will press against the ends of your bag, compressing the insulation there and making it less effective. If your sleeping bag is too long, there will be too much dead space in it and it will take more energy (and longer) to heat it up. Pick the size closest to your measured height. For example, if you’re 6 feet tall, you should be looking for what is described as a 6-foot sleeping bag (though it will actually measure roughly 6-foot 8-inches long, giving a 6-foot tall person the extra room needed for comfort. Most adult bags come in two sizes, regular and long. (Some also come in a short size.)

• Men’s Regular: 78 inches long (fits someone up to 6′)
• Men’s Long: 84 inches (fits someone up to 6’6″)
• Women’s Regular: 72 inches (fits someone up to 5’6″)
• Women’s Long: 78 inches long (fits someone up to 6′)

(Note: Women’s sleeping bags are engineered to fit an “average woman’s” contours. They are typically shorter, narrower at the shoulders and wider at the hips than a men’s or unisex bag. Sometimes they also have extra insulation in the torso and footbox – areas where women tend to feel the cold most.)

If your height is close to the upper end of a size’s “fits up to” spec, try both that bag and the next size up to see which you prefer. Generally, though, you are going to be warmer (and save a little weight) by choosing the smaller of the two sizes.

Additional Features for Your Sleeping Bag

Above are all the major aspects of a sleeping bag that you need to consider when you are choosing a sleeping bag. There are, however, many smaller features of a sleeping bag that you might want to think about because they add that extra bit of comfort or convenience.

Hood

You are more likely to find hoods on bags with lower temperature ratings. Much of your body heat is lost through your head so a snug-fitting hood can make a bag much warmer. A draw cord closure allows you to pull the hood tight against your face for added warmth.

Draft Collar (or neck/shoulder baffle or yoke or face muffle)

Again on cold weather bags, an insulated collar at the base of the hood helps to stop body heat escaping and keeps out the cold around neck and shoulders. Most draft collars will have an adjustable draw-cord to tighten if necessary.

Draft tube

A chamber filled with insulation running the length of the bag along the zipper to help keep warm air from escaping. (Without one, the zipper is basically a weak point for cold drafts).

Inner or Stash Pockets

Normally found near the top of the bag. Handy for keeping valuables such as glasses, wallets and phones safely tucked away.

Stuff sack

Down sleeping bags will come with a stuff sack with a draw string closure (sometimes sold separately) to compress your bag down as small as possible for easy packing. Compression straps help reduce the size of the packed bag. (A down sleeping bag needs to be stored at home in a big mesh or cotton home storage sack so the insulation does not get compressed.)

Pillow pocket

Some bags include a sewn-in pouch to hold a small camping pillow or that allows you to stuff clothes inside to create a pillow.

Anti-Snag Zippers

The smaller the bag’s zipper, the more likely it is to snag, so look for larger, sturdier teeth that will zip more smoothly. Also, look for a stiff backing the length of the zipper, as that will prevent the fabric from bunching and getting caught in the zipper.

Left or Right Zip?: If you’re right-handed, get a sleeping bag with the zipper on the left. If you’re left-handed, get one with the zipper on the right. (If you are lying on your back you want to reach your dominant hand over your body to use the zipper.)

Ancillary Equipment

• Sleeping pad/mat

On a regular, family camping trip you drive up to the camp site in your vehicle and unpack your camping gear including some form of  padding that goes under your sleeping bag – camp bed, hammock, inflatable mattress, etc. If you are hiking and weight is a major consideration you content yourself with a sleeping mat or pad to go under your sleeping bag and provide a little cushioning and, very important, insulation from the ground to keep you warm when sleeping outdoors.(All sleeping bag temperature ratings assume you will be using a sleeping pad.) Some sleeping bags have a sleeve on the bottom to slide your sleeping pad into.

• Sleeping Bag Liner

A separate fabric sleeping bag liner has several functions:

• Adds a few degrees of warmth in the cold weather
• Minimizes sleeping bag wear and keeps your bag clean (and is easy to wash in itself)
• If it is hot you can sleep in just the liner.
• Camping pillow

 Camping pillows are smaller and lighter than standard pillows. Look into lightweight air pillows, cushy foam or plush down-filled ones.”