Mummy sleeping bags are the warmest!
As their name suggests, these bags are shaped like an Egyptian mummy: tapered slightly at the head, and tapered even more at the foot.
They have an attached hood that tightens snugly around the wearer's head, leaving just the face exposed.
My first close encounter with mummy sleeping bags was in the Arctic. I was living and teaching in a small Inuit community, and a friend suggested that we go camping - in the winter!! Once I'd allowed myself to be persuaded, I invested in the warmest, most expensive sleeping bag I could find. Of course, it was a mummy bag.
A mummy bag design is the most efficient design for retaining heat.
A sleeping bag itself doesn't create heat. A warm human body does that! The sleeping bag just holds in the heat created by your metabolism.
The smaller the air space in a bag, the quicker a human body can heat it. That's why mummy sleeping bags are the best cold weather sleeping bags.
If you are planning to camp in the winter, you will want a mummy bag.
No matter what type of bag you have, there are steps you can take to stay warm. Visit this page to learn how to stay warm in a sleeping bag.
Since mummy bags are constructed with as little fabric as possible, they weigh less than comparable barrel bags or rectangular bags. This makes them great to carry - especially if you are backpacking.
Many people find a mummy bag too confining. One sleeping bag reviewer described the sensation as "that horrible, helpless feeling of being confined in a straightjacket". If you have a tendency to be claustrophobic, a regular mummy bag is probably not for you!
You might prefer to check out barrel sleeping bags - or try the Sierra Designs Mobile Mummy bag.
The ingenious design of this sleeping bag solves the problem.
The hood fits snugly, like the hood of a jacket.
Reviews report that they do not feel claustrophobic in this bag as in traditional mummy bags.
There are even ports for your arms and legs so that you can walk around wearing your bag like a parka!
When you move inside a mummy bag, the bag moves with you. If you move a lot in your sleep, this can be a problem.
It is possible to roll over onto your side - but chances are that you will roll right off of your sleeping pad in the process! (And if it's cold enough that you need a mummy bag, you definitely don't want to roll onto the bare ground!)
If this sounds like it will be a problem for you, consider buying a Big Agnes sleeping bag.
Most have an attached sleeping pad sleeve.
You slip your sleeping pad right into the sleeve. When you move, your sleeping bag and sleeping pad move with you!
You can't zip mummy bags together as easily as you can rectangular bags. If you like cuddling with your sleeping partner, mummy bags won't be your first choice.
(Mummy bags will zip together, but they won't be very comfortable! Click here for a photo, and to learn more about all types of sleeping bags that zip together.)
Not all mummy sleeping bags are alike! Here are some of the features to consider.
A mummy bag for use in extreme cold weather should have a neck yoke (or "draft collar"): an attached fabric panel that fits snugly over the shoulders and around the neck. This keeps cold air out of the bag.
If you are going to do any winter camping, you will want a yoke. If not, it's not necessary.
Some mummy bags have no zipper. This reduces the amount of heat lost through the zipper, but makes it difficult to get in and out - and may compound the claustrophobic effect.
Others have a short zipper, and some have a full zipper. I prefer a full zipper for ease of use.
A draft tube is a flap of fabric covering the zipper.
This, too, is a necessity for winter camping. Be sure that the draft tube is as long as the zipper.
Your choice of material will depend on how and where you are going to use the bag. In very cold, dry conditions, a down bag is appropriate. (My Arctic mummy bag was down filled.) Click here to learn about down filled sleeping bags.
If you are camping in a damper area, you might want to consider a synthetic bag. Read about synthetic sleeping bags here.
This is a circular panel (like the end of a tin can) at the end of the bag.
It gives your toes some wiggling room when you are lying on your back.
I was surprised to learn that there is such a thing as a double mummy sleeping bag.
I don't think that you'd be able to tighten this up as snugly as a single mummy bag. If you and a partner are doing extreme cold weather camping, you'll each want your own bag.
This bag gets great reviews for moderate weather camping, though!
If you are planning to camp in conditions of extreme cold, then a mummy bag is what you need.
Although I am not particularly comfortable in a mummy bag, I know from experience that in extremely cold weather, warmth is more important than comfort!
If you'll be camping in moderate temperatures, and are considering a mummy bag because of its relatively light weight, try it out in the store before you buy. You may find that you like it - or you may feel so confined that you opt to buy a barrel bag or rectangular bag in spite of the extra weight.