A good sleeping bag is most likely to be one of your more expensive pieces of outdoor gear...
Back in my university days, I took a holiday with friends to southern France and Andorra. We were hiking in the mountains in Andorra and decided to spend a night in one of the many free mountain huts across the country. More than twenty years later, I still remember this night as being one of the coldest and most uncomfortable nights of my life. It probably didn’t actually get that cold that night, perhaps only -5C.
However, there were five of us and we had two light-weight, super cheap sleeping bags between us all. Here we were, four early 20-something guys and one girl, all huddling, shivering and clattering on the wooden bunk-bench of the hut, with two sleeping bags thrown across us all.
Sleeping cold sucks. Being unprepared in a cold climate is not only very uncomfortable, but in some circumstances, can be quite dangerous. Owning a cold weather sleeping bag and being able to stay warm will be a foundational piece of kit for any cold weather overnight activity.
A good sleeping bag is most likely to be one of your more expensive pieces of outdoor gear. Below, we’ve provided a comprehensive guide of all things to consider when buying a cold-weather sleeping bag.
Perhaps the most important consideration when choosing any sleeping bag is the temperature rating of the bag. Too warm and you’ll be sweating it out during the night. Too cold and you’ll be awake all night. In extreme cases, too cold, and the risk of hypothermia or worse.
Since 2005, most European countries and increasingly many other countries have adopted a new standardised way to measure the thermal properties of a sleeping bag. This standard moves away from the above “Season” rating and recommended retailer temperature guides and instead moves to an independent standardised way of testing a bag. The European EN13537 (like an ISO standard) measure provides a standard temperature result for normal sleepers.
I’m a woman, not a man!
Men will generally sleep a few degrees warmer than women. So when the temperature drops, women will be more likely to feel the cold sooner. Also, few of us are “standard”. Our height and body fat will also impact how easily we feel the cold.
NOTE: Just because a bag does not use the EN13537, does not mean the recommended temperature ratings are not valid or that the bag is any less effective. It does however mean that the ratings provided are from the manufacturer themselves. You may want to understand what in-house testing they have completed.
So what do I pick?
The recommended temperature rating of a bag is the temperature rating at which a normal person is likely to stay asleep. For many people, the you get closer to that temperature, the more likely you wake up. As it starts to get colder than the temperature rating, then you are almost certainly going to wake up and be cold. Generally speaking you should look to purchase a bag that is warmer than the expected ambient temperature. If you wake up warm you can undo the sleeping bag. If you wake up cold, there’s not much you can do.
Down or Synthetic
Choosing between down or synthetic is an age-old debate as to why to choose one of the over. While both versions have their pros and cons, generally speaking down fill will last longer than synthetic fill, pack smaller, and have a better warmth-to-weight ratio (ie lighter for the same warmth). Synthetic bags are generally cheaper and perform better when wet (down loses its thermal qualities when wet and is unlikely to remain completely impervious to moisture even with a water-repellent protection). While the weight to thermal properties of synthetic fill is continuously getting better, good quality down still offers the best weightto-warmth ratio available. If you are going to be in cold, dry conditions, down is your better option, whereas synthetic is a better choice for cold wet conditions.
Find Your Sleeping Bag
FEATURES OF A SLEEPING BAG
Shell and inner materials: What and how is the external and internal fabric of the made of? Many bags will feature a waterproof and/or breathable outer shell, including a DWR (durable water repellent) coated shell to prevent condensation, snow and rain from soaking through. Many manufacturers have developed specific fabrics, unique to their own bags and it is worth understanding what benefits these fabrics provide (strength, durability, weight, breathability, water resistance, down-proof construction).
Baffles: are compartments within the sleeping bag designed to prevent the insulation from moving around too much, causing cold spots. Some bags allow you adjust the fill for your own preferred comfort.
Hoods: Essential for cold weather. 80% of body heat is lost through your head, so a good hood that can be drawn tight is important for cold weather.
Zippers: Does the bag completely open or only partially open. Are the zippers one or two directional? Is there a left or right option? What size are the zippers? Trying to fiddle with a zipper during an icy cold night can be extremely frustrating. Do the zippers have anti-snagging protection or their own baffle to prevent heat loss?
Pockets: Can you store anything inside your bag?
Foot Box: Designed to keep hold and keep your feet warm. Consider the construction, specific thermal qualities and weather any additional durable or waterproof materials have been used.
Hang Hooks: Being able to easily hang your bag at home is always handy.
Stuff sack and storage sack: Many manufacturers will provide both. The stuff sack is all about getting the bag as small as possible, while the storage sack should be big and airy to allow plenty of circulation while in storage.
There are a lot of things to consider when buying a sleeping bag and each bag really is designed for a specific reason. You should think about the conditions in which you will most often use your bag, the likely high and low temperatures you are going to find yourself in, the importance of weight and stuff size, and of course your available budget. It is not uncommon for many outdoor enthusiasts to own a couple of different bags, each to be used under certain conditions.
WINTER SLEEPING BAG TIPS
1. Wear a beanie or neck gaiter and your entire body will feel warmer during the night
2. Wearing thermals will also keep you warmer
3. Put a change of clothes into your bag stuff sack to use as a pillow
4. Put sock, gloves and underwear in your bag and they should be dry by the morning
5. Try and lay out your sleeping bag 30 minutes before you plan to sleep, as this will allow the loft to expand to achieve its maximum efficiency
6. Keep a torch handy in case you need it during the night
7. If you wear contact lenses, keep them inside your bag to avoid them from freezing
8. The type of mat you use will make a big different in keeping you insulated from the ground and its worth considering the different options.
FIT AND SHAPE
The shape of bag is designed to provide a balance between comfort and performance. A larger bag with more room internally will give you more freedom and space internally and likely be a little more comfortable. However, this added freedom is at the expense of thermal properties with the greater movement of air reducing the bag’s thermal efficiency.
Bags will traditionally come in three shapes:
Mummy: The most thermal efficient bag. Wider at the shoulders and tapering down at the feet. These bags are generally the lightest, pack down the best and are the warmest of the bag shapes.
Tapered/Barrel: These are less fitted than a mummy bag, but still taper at the foot, reducing dead space and the air to be heated within the bag.This style of bag is a good all-round choice as they are comfortably roomy but still pack down well.
Rectangular: Roomy and comfortable, these bags give you plenty of space for moving around. These are designed for uses where warmth, packed size and weight are not critical as they are generally larger and heavier.
Storing your sleeping bag: You might be tempted to keep your bag neatly tucked away in its stuff sack. However, over an extended period of time this will reduce the lifespan of the bag. When you get home, unzip your bag and air it out ensuring it is completely dry. The best way to store your bag is loosely hanging from a hanger, otherwise in large pillowcase or cotton bag. Many bags will come with both a stuff sack and larger storage bag.
Liner, Mattress and Tents: In addition to your bag, you should also consider a sleeping bag liner and the type of mattress you use. While a liner is likely to increase the temperature efficiency of you bag by a few degrees and also make cleaning your bag easier, a mattress will not only keep you insulated from the cold of the ground but will also provide a much more comfortable sleep. Finally, the tent in which you find yourself sleeping may have a significant impact on the ambient temperature of the surrounding air. Summer tents are designed to be airy and allow good air flow. Winter/Alpine tents are not.
A sleeping bag’s role is to trap a person’s warmth and prevent it from escaping, keeping them toasty. Talk through your needs with your local Rays staff and ask for additional information and advice.