How

to

Choose

the

Right

Sleeping

Bag

Down vs. synthetic materials: Which is better?

Depending on the material they’re made out of, sleeping bags  come with different benefits and qualities – especially when you need to choose between down or synthetics. 

Light like a feather: Down sleeping bags

Because of their high quality, down sleeping bags  are slightly more expensive than their synthetic counterparts. Classically filled with fluffy duck or goose feathers, they are very durable and offer great heat insulation. The fill absorbs moisture very well and releases it in a fully controlled way, providing maximum comfort while sleeping. Plus, the lightweight nature of the fill makes for a small pack size. Down is generally a good choice for all types of activity and outdoor conditions. The only downside: If your sleeping bag gets really wet, the feathers start to clump and lose their insulation qualities. So it’s best to not use a down sleeping bag when there’s heavy rain or a lot of dew. If you do use it in these conditions, make sure to air it out and dry it frequently. If you don’t want to give up on your feathery goodness even when it’s wet, down fills with impregnation are a great choice as they are water repellent and  damp-proof. And if animal welfare is something you are very mindful of, keep an eye out for down from responsible animal farms , often indicated by sporting an RSD certification (Responsible Down Standard).

Synthetics – versatile & damp-proof

The vast majority of synthetic sleeping bags  are made out of hollow polyester fibers which are woven together into a multi-layered, tightly woven fleece to provide the necessary heat insulation. As they’re much cheaper to produce, they usually come in at a lower price point. However, they are also a lot less durable than down. The biggest advantage of synthetic fibers: They’re super easy to handle and to clean, and also suitable for anyone suffering from allergies. Just like performance clothing they don’t retain moisture, meaning they will still offer perfect insulation even when wet – and they dry quickly, too. So if it happens to be particularly dewy in the mornings or you’ve accidentally spilt your drink, you’re still good to go for the night. On the flipside: Less moisture absorption also means that moisture isn’t wicked away from the body as effectively compared to natural fibers, which can negatively affect your sleeping comfort. Synthetics also can’t keep up with their natural counterparts when it comes to weight and pack size as they’re heavier and more voluminous.

When to use which sleeping bag

Once you’ve settled for our preferred type of stuffing, it’s time to choose the right model – make sure to focus on size, shape and the right temperature.

What does comfort temperature mean?

The different types of sleeping bags are determined by three different levels of thermal insulation:

• comfort zone – T comf

• lower limit – T lim

• extreme zone – T ext

Before making your purchase, you need to factor in the surroundings you’ll be in throughout your tour, as well as the coldest possible temperature you may be exposed to during the night. This value should be covered by the comfort zone range of your new sleeping bag – comfort in this case referring to a temperature which allows you to just about sleep comfortably without freezing. The lower limit, as the name suggests, indicates a temperature that is just about fine to bear for the average person. The extreme zone refers to conditions where you’re exposed to extremely low temperatures, with a high risk of hypothermia.

That being said, how sensitive someone is to the cold depends entirely on the individual. So think about how well you’re generally coping with low temperatures, and choose a sleeping bag with a comfort zone that allows for a bit of wiggle room. If worse comes to worst and you feel like you’re getting too hot, you can always open your sleeping bag.

Which sleeping bag for which temperature?

Want to know which sleeping bag is the perfect choice for summer and winter? The shape and characteristics of sleeping bags are adapted to match the relevant thermal insulation level. There are five types:

1. Summer sleeping bags: A light and breezy option for warmer nights, ideal for comfort zone temperatures north of 42.8 °F.

2. 3-season-sleeping bags: These types of sleeping bags are designed for temperatures that lie somewhere between the comfort zone of winter and summer sleeping bags – usually 24.8 °F to 41 °F. They’re the perfect allrounder, and a great choice for any type of outdoor activity in the summer, spring or autumn.

3. Winter sleeping bags: These are designed to keep you warm – as such, they’re specifically made for freezing cold nights, with the comfort zone covering temperatures ranging from 23 °F to -0.4 °F.

4. Expedition sleeping bags: These types of sleeping bags do not correspond to the standardized ratings above because they’re usually used for temperatures far outside the normal values. They’re designed for conditions close to the limit, for example freezing cold nights during winter or alpine tours. Expedition sleeping bags are ideal for temperatures starting at -22 °F and lower.

5. Sleeping bag liner, ticking or inlay: This type of sleeping bag is very compact, lightweight, breathable and machine washable. It’s perfect for use in cabins, hostels or as a thin sleeping bag during the summer. For an added layer of warmth and better hygiene, you can also use the inlay as additional inner lining for your regular sleeping bag.

By the way: Another value or indicator to keep an eye on is fill power: This tells you how long it takes your sleeping bag to bounce back after compression. The value should be above 600 cuin, while anything above 800 cuin is an indicator for a high-quality product.

What size should my sleeping bag be?

To find the right sleeping bag size, it’s best to try them out in person: Your sleeping bag should never be too small or too big to ensure the perfect level of thermal insulation. If you’re squishing the fill because it’s too tight of a fit, you’ll lose a significant amount of insulation. Same goes for loose sleeping bags, as you’ll have to compensate for the empty space inside with our own body heat. So when making a choice, pick a model that’s as close to your actual body size as possible. Added bonus: You don’t need to carry around unnecessary excess weight. When trying out sleeping bags, ensure you’ve got a hand’s width of space between the sleeping bag, your feet and your head – also with the hood on. Lie inside the bag in your usual sleeping position and see if you feel fully comfortable. And speaking of comfort: If you want to treat yourself to something extra special, you can opt for a sleeping bag with a pre-formed foot box so your toes won’t come into contact with the outer layer.

Sleeping bag shapes

In addition to the right size, the shape of the sleeping bag should also complement your body shape. There are three types:

• Mummy sleeping bag: As their contour pretty much corresponds to the human form lying down, these sleeping bags usually boast a very accurate fit. This not only makes for added overall comfort while sleeping, but also helps you reduce pack weight while providing highly effective thermal insulation because all available space is filled out – perfect for when you need to stay warm and quality is key. The only downside: There’s a lot less wiggle room compared to other models.

• Rectangular sleeping bag: In this type of sleeping bag, you’ll feel like sleeping in your very own bed. Thanks to its rectangular shape and a zipper that goes all the way around, it gives you maximum freedom of movement, including the flexibility to use it just like a duvet. The extra comfort, however, comes with a couple of compromises in the way of pack size, weight and insulating properties. While not the best companion for mountain treks and long hiking tours, it’s a great choice for camping trips, summer festivals or overnight stays in cabins/hostels – and even doubles as a duvet for your guests if needed.

• Barrel-shaped sleeping bag: This type of sleeping bag provides the best of both worlds: Its barrel-shape provides extra space and more freedom of movement than a mummy bag, while also keeping you warmer than the rectangular variant. Nonetheless, you’ll have to compromise somewhat on weight and pack size. While barrel-shaped sleeping bags don’t offer the same insulating properties a mummy sleeping bag would, they are still a great choice for camping and outdoor activities in moderate temperatures.

Sleeping bag accessories for added comfort outdoors

A good night’s sleep all comes down to comfort. A camping mat will give you the necessary cushioning on hard floors, while also providing extra heat insulation to keep you warm. To reduce the frequency between washes, inlets are a great choice. Also worth investing in, particularly on long tours where there’s a high chance of your sleeping bag coming into contact with dirt or moisture, is a water-repellent compression bag.

For more handy accessories for your sleeping bag  and other high-tech gear, check out our Mammut Shop. Or discover our Mammut Stories & Guides  to find out what type of equipment and sleeping bags our top athletes  are using.