Choosing a sleeping bag is an essential decision. It determines your sleep quality, your comfort, how well you recover, and offers the genuine moral benefit of truly relaxing in a cocoon. A good sleeping bag is therefore important for any hiker, whether on long multi-day trips or shorter hikes of just a few days. Let's look at 6 essential criteria for choosing a sleeping bag suited to your needs and your hikes.
Comfort temperature
The first selection criterion when choosing a sleeping bag is temperature. Among the temperatures listed, the one to focus on is the comfort temperature. This is generally the figure highlighted by the manufacturer or retailer. It indicates the temperature down to which you will be comfortable in the bag without feeling cold.
This should not be confused with the lower limit comfort temperature, which indicates the temperature at which you need to curl into a foetal position to avoid feeling cold. Then there is the extreme temperature — the point at which you will feel cold in your bag even in that position. Below this temperature, the risk of hypothermia is real, and it is strongly inadvisable to be exposed to it for an entire night.
Key criteria for choosing the comfort temperature of your sleeping bag
To choose a bag with the right comfort temperature, you need to consider the geographical area of your hikes and the altitudes at which you will be sleeping. But also think about your bivvy conditions (open air, tent, mountain hut), the season and of course the weather conditions (not just temperature, but also the risk of bad weather).
Bear in mind that even in temperate zones in summer, temperatures can drop significantly at night once you are at altitude. Humidity and wind are also important factors. Cold sensitivity varies between individuals depending on their build and fitness level. If you feel the cold easily, opt for a bag with a comfort temperature a little lower than the temperatures you expect to encounter. Also remember that you'll feel colder when tired and when you haven't eaten.
For a summer night, a sleeping bag with a comfort temperature of +5 degrees is sufficient. In mid-season, a temperature of 0 degrees is recommended. For winter and cold nights, you should opt for a comfort temperature of at least -5 degrees.
The temperatures indicated by manufacturers are reliable and comply with European standard EN13537. This standard has the advantage of making bags from different brands directly comparable on this criterion.
And if you use your sleeping bag in variable temperature conditions, you can add a silk sleeping bag liner or a fleece mummy liner to gain a few extra degrees.
Weight
For fully self-sufficient hiking, weight is an important criterion. For other types of hiking, the weight of the sleeping bag still matters, though it is slightly less critical. Down sleeping bags offer the best weight-to-temperature ratio, but there's no magic solution: you won't find an ultra-lightweight sleeping bag for low comfort temperatures. Weight is therefore an important criterion, but often a matter of compromise when choosing a sleeping bag suited to your needs.
Choosing your sleeping bag fill
A synthetic sleeping bag is often heavier than a down bag at the same temperature rating. It is also less compressible. However, it performs better in damp conditions. It is therefore particularly well suited if your bag is likely to be exposed to wet weather, or for example if you are sleeping under the stars in a humid area. And finally, a not insignificant advantage: synthetic bags are also more affordable than down bags.
A down sleeping bag is lightweight, compressible, highly insulating and breathable. However, it loses its insulating power when wet. The drawback of down feathers is that they tend to clump together with moisture, reducing insulation quality and thermal comfort. Furthermore, over time, down fill can develop the unfortunate tendency to bunch up in certain areas of the bag, compromising the consistency of comfort and insulation.
Choosing a synthetic-fill sleeping bag is therefore a solid compromise for value for money and for expeditions where weight is less of a priority.
Sleeping bag shape
Mummy sleeping bags are anatomically shaped: they follow the body's contours and thus optimise thermal protection. They are also lighter and less bulky than blanket-style bags. However, they can feel a little restrictive, and some people prefer the freedom offered by a blanket-style bag.
Blanket-style sleeping bags are more comfortable as they are roomier around the feet. However, with comparable fill, they offer less effective thermal protection as they contain more air. They are, on the other hand, easier to get in and out of and simpler to use.
The closure system
This element is important to prevent cold air from seeping into the bag and warm air from escaping. There are different types of closure, sometimes with tightening systems on the hood for mummy bags. Above all, pay close attention to the quality of the zip and the finish. You'll be operating this zip a great many times, and you certainly don't want to end up stuck inside! So carefully avoid any models where the zip feels flimsy or awkward to use.
Compressed volume
This is an important criterion if you don't want to be burdened with an overly bulky bag. Down bags compress better and are therefore generally less bulky than synthetic bags. That said, it is not the most important criterion when making your choice. But it can help you choose between two otherwise equivalent products.
The perfect sleeping bag doesn't exist. You need to choose one that suits your needs and the types of hiking you do. If you mainly go on multi-day hikes without requiring full self-sufficiency, you don't need an ultra-light, highly compressed bag. Prioritise comfort and insulation instead! Conversely, for long expeditions, packability and weight will become more important criteria. You can also own several sleeping bags suited to different conditions and types of hiking. In any case, one thing is certain: choose a quality sleeping bag — it's an essential companion on your treks and multi-day hikes.
Check out our article on: How to care for and wash your sleeping bag.
