Debunking Sleeping Bag Jargon

Sleeping bags are probably one of the best investments you can make if you are an avid camper or explorer, and if you’re not then it may be best to hire one in-country*.  

Ultimately, if you are looking to purchase your own sleeping bag, it can all get quite confusing so this blog is designed to defeat the jargon used in many shops. It’s important to note, that a certain element of sleeping bag shopping is down to personal choice- how hot you get when you sleep, how much you toss and turn or whether you want to share a bag with a partner or friend.

It’s important to note, that a certain element of sleeping bag shopping is down to personal choice- how hot you get when you sleep, how much you toss and turn or whether you want to share a bag with a partner or friend.


So first things first, let’s talk numbers, what do they all mean? When you’re walking into any well-known mountaineering shop, they’ll probably have different words or phrases, so I’ve popped some definitions below to help you out.

Comfort Rating: This one is entirely down to personal choice, and refers to the temperature you believe you’ll be feeling ok to sleep in. When using your sleeping bag at temperatures below your “comfort” temperature, you’re likely to feel the cold.

Extreme Rating: This rating refers to the bag’s “survival temperature”. To be frank, this is the minimum temperature the bag will keep you alive in (without frostbite). Therefore, this is not the lowest temperature you’ll feel comfortable in, and therefore you should not expect to use your sleeping bag regularly at this temperature.

Sleeping Bag Season: 

Some sleeping bags are designed to be much thinner, and therefore only suitable at particular times of year/temperatures. The Season rating, refers to exactly this. In other words, the higher the season rating, the lower the temperature the bag can be used in.

So, overall:

Season 1: sleeping bags are only suitable for during summer temperatures, so those of you headed out to Brazil should be ok with a Season 1-2 bag (as even at night, temperatures shouldn’t fall below 17 degrees C).

Season 2: Suitable during Summer/Spring

Season 3: Suitable for Spring/Summer/Autumn: Those of you headed out to Iceland this Summer should be ok with this temperature grading as temperatures should not drop below 10 degrees at night in Iceland.

Season 4/5: If you’re going to be taking on a high altitude trek this Summer in Peru, Tanzania, or Nepal you’re going to need a good quality sleeping bag (an all season or 4 season sleeping bag). This style bag will be suitable for all seasons- and so at higher altitude and lower temperatures, it should still keep you nice and comfortable to sleep in. It’s important to note that you should still pay attention to the extreme & comfort ratings on the bag- as these can still vary between bags of the same season grading.

Next up, the shape.

Mummy sleeping bags have a tapered shape, they can be quite a snug-fit and come with a warm hood too. This ultimately is one of the warmest and (in my opinion comfiest shapes). However, if you move about a lot in your sleep you may be better suited to something roomier.

“Sleeping Pod”
Sleeping pods are designed to offer those who toss and turn in their sleep, plenty of room to do so. However, the sleeping pod design may not be the warmest, as all of the extra space around your body could lead you to get colder easier. Definitely worth substituting roomy-ness for warmth, particularly on the colder treks.

Alternatively, you could take things back to basics and opt for a square bag. Square bags offer more space to move your feet than a mummy bag – so for those who struggle to sleep whilst feeling constricted- this style bag will probably be the one for you. Square bags can be doubled up too- so if you fancy sharing a bag with a partner then a square bag may be the one for you (you’ll need to check with the shop/supplier to ensure the exact bag can be doubled). 



Sleeping Pod 

Sleeping Pod 



Materials. Synthetic vs Down:

Synthetic is the most common type of sleeping bag filling. It is a lot cheaper/easier to clean than down sleeping bags. They also perform better when wet, but you shoudn’t need to worry about this unless you have an accident with a water bottle in your tent!


Down sleeping bags, although a little more expensive and a little less hard-wearing when wet/damp, are noted as much better when it comes to holding heat. The fluffy-nature of the material creates lots of tiny air pockets in the filling, meaning it can easily store warm air to keep you nice and toasty. It’s also a lot lighter, so when it comes to making sure you’re under your weight limit for your kit bag.

If you want to get even more fancy, or specific, here’s a couple of other last things to look out for when buying your sleeping bag..

A pocket on the inside: On the cold nights of your trek, it’s important to keep your batteries, cameras, and electronic devices as warm as possible so as to prevent them draining the battery. A handy pocket inside your sleeping bag means they stay warm, and you won’t lose any valuables whilst you sleep.

A sleeping bag liner: To liner or not to liner, that’s a very good question. Ultimately, there’s several reasons as to why you should opt for one of these. However, from personal use I don’t quite see the benefit so much myself. Again this one is entirely down to personal opinion. One of the main reasons liners are so popular with trekkers is their hygiene benefits, to quote an article on webtogs “you wouldn’t sleep in a bed without sheets on”, sleeping in a bag without a liner is believed to be the same thing. A liner provides a removable, easily washable sheet to keep things clean from trek to trek. A good quality sleeping bag can also provide up to 2 degrees of extra warmth- which may not seem like a lot, but can make all the difference in the colder temperatures higher up a mountain. So with all the benefits, why wouldn’t I personally rate it? Well unfortunately I opted for a silk liner on my Kilimanjaro trek, and found that although it was lovely and warm whilst it was in place, as a certified “wriggler”, I found that roughly 1 hour into sleeping the liner was around my ankles. Annoying, yes, but at least it kept my feet nice and toasty. Overall, I’d probably recommend a liner, but i’d also recommend finding a way to tie it to the top of your sleeping bag to ensure it doesn’t slip like mine did.

A final peice of advice from me would be, when it comes to sleeping bags- don’t scrimp. Your sleeping bag will be the difference between you getting no sleep on the mountain, and you getting a good rest. Overall, the more well-rested you are, the more likely it is that you’re going to reach the summit/end of your trek feeling fresh & ready for that all important Facebook photo. Invest in a bag that’s going to do the job well, and if you don’t think you’re likely to use the bag again? Rent one in country for the duration of the trip!*

*Subject to country you will be travelling to, check briefing pack or get in touch.

Lucy Dalglishtrekking, kitComment