Is your sleeping bag failing to keep you warm during the winter months?
Do you remember it being…warmer? Does it seem to have lost its warmth over the years?
Maybe you have a sleeping bag that’s better suited to the summer months, you’re about to head out in winter, and don’t want to buy another sleeping bag?
If this sounds like you, this blog lists 5 toasty tips for a warmer sleep – but first, let’s bivvy down and learn a little more about the humble sleeping bag…
Brrrr, winter camping can get positively arctic if your sleeping bag isn’t warm enough! Credit: Sea to Summit
The Sleeping Bag
Sleeping bags are one of the only products on the market that have a temperature rating. Think about it, it’s not common to buy a jacket or even a quilt for your bed at home with a temperature rating.
As a general rule, if we feel cold we put an extra jumper on or another blanket on the bed. Despite this, we expect that a sleeping bag with a ‘temperature rating’ of 0 degrees will keep us toasty warm in the snow, no matter what type of person we are.
The reality is that this temperature rating is only a guide. We all feel the cold differently, so we simply cannot expect a sleeping bag to reflect such science – or that one temperature rating fits all.
So, what does temperature rating mean? How can we use this roughly equated number to help us choose an appropriate bag for the job?
We all feel the cold differently. Credit: Sea to Summit
Sleeping Bag Temperatures
Before delving in – ask yourself:
- Do you usually go camping during cold weather, when it’s warm, or both?
- If the weather is forecast to be cold – how cold? Is there a chance of frost or snow?
- Are you sleeping outside, or in a tent? How large is the tent? Is it just for sleepovers?
With those considerations in mind, let’s talk sleeping bag ratings:
+5 to +10-Degree Bags
A +5 to +10 is considered a ‘summer’ bag. It is roughly as warm as sleeping with a sheet or light blanket on your bed at home.
0-Degree Bags
A 0 degree bag is a great all-rounder, but won’t keep you warm in the snow or frost – it’s about the same as having a regular doona on your bed at home.
-5 to -10-Degree Bags
A -5 to -10 degree bag is considered a ‘winter’ bag for typical Australian climates – it should be similar to having flannelette sheets and an extra blanket or two on your bed at home.
Choosing Your Sleeping Bag
The temperature rating is the point at which you will likely wake up to. You will feel cooler as the external temperature approaches this rated temperature, so it’s important to allow yourself a temperature buffer. The below factors are worth considering to help select the right bag for you.
- First, determine the lowest temperature you will be using the sleeping bag in most of the time.
- From here, we recommend adding a buffer to ensure you sleep warm. This is dependent on how you sleep:
- Warm sleepers: refer to the EN/ISO tested ‘Comfort’ rating as a starting point, and choose a bag with a rating at 5 degrees below the lowest temperatures you plan to use your sleeping bag in.
- Cold sleepers: refer to the EN/ISO tested ‘Lower Limit’ rating as a starting point, and choose a bag with a rating at 5-10 degrees below the lowest temperatures you plan to use your sleeping bag in.
- Keep in mind that you can expand the comfort range of a sleeping bag by adding liners for extra warmth, or use the sleeping bag unzipped as a doona to cater for temperature extremes you may occasionally encounter.
- Finally: this is not an exact science. We are all different, with varying metabolisms. You’ll need to use some of your own judgement in your selection.
You will feel cooler as the external temperature approaches the sleeping bag’s rated temperature. Credit: Sea to Summit
EN/ISO Temperature Rating
Sleeping bags must be independently tested by the manufacturer to obtain this rating. The rating is often based on an R-value, which is a measurement of insulation – just like the insulation in the walls of your house.
Some manufacturers will do real world testing on one sample of their insulation, and apply a formula to the different sleeping bags. On the other hand, sleeping bags tested to an EN (European) Standard (or an ISO or international standard as of 2016), are the most accurately tested bags.
That said, keep in mind that this testing is done in a controlled and static environment where a dummy is placed inside the sleeping bag with temperature sensors. So, unless you’re a motionless dummy sleeping in an environment void of variables, you’ll need to allow for your own physiological makeup and the equipment you are using.
What is the EN or ISO Standard?
There are no testing guidelines here in Australia, so look out for bags that have been tested according to EN Standards. The EN Standard for sleeping bags is marked EN13537, which was superseded by the ISO 23537-1 international standard in 2016.
The standard measures three temperature ratings:
Comfort
The temperature at which a standard woman can expect to sleep comfortably, without feeling cold and in a relaxed position.
Lower Limit
The temperature at which a standard man inside the bag sleeping in a curled position is starting to feel cold, but not shivering. This is the limit of performance for the sleeping bag.
Extreme
At this temperature, anyone can expect to feel particularly cold with a risk of hypothermia. You should only use the sleeping bag in this range for an emergency.
Look out for bags that have been tested according to EN Standards. Credit: Sea to Summit
Not all manufacturers will list all three ratings – ensure you’re considering the correct one. Ultimately, no amount of laboratory testing is going to be 100% accurate to your body. Less expensive sleeping bags will advertise a more generous rating that may not be accurate. Bags that list the EN/ISO Standards will be more accurate and provide a good point for comparison between bags. As that process is expensive though, it will affect the price tag.
You can always shed a layer or unzip your bag if you’re hot – but if you wake up freezing cold in the middle of the night, there won’t be much you can do to get warm!
On that note, below are five ways to improve the warmth and therefore quality of your sleep on those colder camping trips:
1. Wash Your Sleeping Bag
If your sleeping bag is on the ‘well-used’ side and doesn’t seem to be as warm as it once was, you may need to simply give it a good wash. Over time, the oils from your skin together with moisture caught in the filling can cause the stuffing to clump together. This prevents it from ‘fluffing up’, which keeps you insulated and warm.
The filling in the sleeping bag needs to ‘puff up’ and expand with air, which then traps the body heat of the person sleeping inside. Washing your old sleeping bag will clean the filling and enable it to do this more effectively, thus trapping more warm air and increasing the insulation between the person inside and the cold air outside.
Wash your sleeping bag to restore its warmth.
How to Wash Your Sleeping Bag:
- Put your sleeping bag in a pillowcase to protect the thin outer material from tearing.
- Using a front loader, wash your sleeping bag on a warm, gentle cycle (if you have a down sleeping bag, use Down Wash).
- Dry your sleeping bag in a large tumble dryer on the lowest setting. Place a few tennis balls inside the dryer too; these will smash into the sleeping bag, breaking up the filling and fluffing it up again.
- If you don’t have access to a dryer, simply dry the sleeping bag on the clothesline in the sun. Every half an hour or so, beat it with a tennis racket to break up the filling.
In an ideal world, you would have a sleeping bag for every season. But in reality, you can make one sleeping bag a lot more versatile with a few of these hacks. Credit: Sea to Summit
2. Thermal Liners and Hot Water Bottles
Thermal Liners
If your sleeping bag isn’t rated low enough for the conditions you’re using it in, or if you’ve discovered you’re a cooler sleeper – rather than purchasing another sleeping bag, consider adding a silk, cotton, or fleece liner.
A thermal liner is made of the same material as thermal underwear, specifically designed and rated to boost the warmth of your sleeping bag. While there are many on the market, the cotton and silk liners by Sea to Summit are a personal favourite.
By adding a liner to your bag, you not only have a sufficient winter sleep system but can still use the sleeping bag on its own in average conditions. The liner can then be used on its own in warmer weather! A removable liner also keeps your sleeping bag cleaner, and thus your filling in better condition.
On the contrary, avoid adding extra blankets on top of your bedding. The weight will crush the filling, rendering it ineffective for trapping the air. Use them beneath you, or under your mat instead.
Hot Water Bottles
If you’re heading away for a particularly cold weekend, it may be worth packing a good ol’ fashioned hot water bottle too. You can also use a regular water bottle – just ensure it has a quality seal so it won’t leak, and the water inside isn’t too hot. Sports-style bottles aren’t usually a good idea, but the Nalgene, 360 Degrees Stainless Steel drink bottles and those alike work well.
Heat the billy before bed and pour the hot (not boiling) water into your bottle. Tuck it into your sleeping bag with you – and enjoy some seriously snug comfort! Better yet, if you prepare it ahead of time, you’re pre-heating your bed so it’s warm by the time you officially hit the sack!
Layer thermals under your clothes while you sleep. Credit: Sea to Summit
3. Thermal Clothing
Thermal underwear are the warmest pyjamas you will ever need when camping in cold conditions! Known as a ‘base layer’, they will trap warmth directly against your skin and make a huge difference to your comfort in cold conditions. Layering clothes on top of your thermal base will trap air between the fabric, keeping you warmer than simply adding a single thick layer of clothing.
Ensure you add your layers and warm up by the campfire well before lights out too, so the heat has time to build. This will also have it easier to maintain, as it will be trapped with you when you slide into your sleeping bag.
Keep your extremities warm on a cold winter’s day. Credit: Sea to Summit
4. Beanie and Socks
Humans lose about 30% of their body heat through their heads! By wearing a beanie to bed or tightening the hood of your sleeping bag, you’re trapping more warmth. Simply keep your mouth and nose free so you’re not breathing into your bag – this creates moisture throughout the night.
When your body becomes cold, it takes blood from the extremities such as your feet and hands to instead keep it surrounding your vital organs. By heading to bed with warm socks and gloves, you’re keeping your feet and hands warm, which maintains the blood flowing to them. This makes for a better night’s sleep!
Tuck into a large dinner before bed. Credit: Coleman
5. Eat a Big Dinner!
Your body uses a lot of energy to digest big meals. In the case of a large dinner, all this energy will produce heat and keep you warm come bedtime. By eating a decent sized dinner packed with low GI carbohydrates, your body will continue to burn fuel all through the night!
Two-minute noodles give you enough energy for… well, two minutes. On the other hand, a big bowl of spaghetti Bolognese will ensure a good night’s sleep! Just don’t eat too much…and go easy on the garlic, or you’ll be awake with indigestion! Contrary to popular belief too, if nature calls during the night you are better off surrendering to it; holding on will override your kidney’s signal to your brain. Through a chain of technical temperature regulation measures, our bodies feel colder when our bladder is in need of relief!
Hopefully, this advice will help keep you snug while you sleep. Credit: Sea to Summit
Keep Warm on Your Next Adventure!
No matter the age or quality of your sleeping bag, these tips will help you achieve the best from it.
It’s worth noting too that your sleeping bag is part of a whole sleep-system. This means that your choice of sleeping mat will also influence how cold or warm you will be throughout the night.
An airbed is not one to keep you warm, as the air within the mattress will remain cold. Instead, choose a closed-cell foam or filled mat, which traps air and helps insulate. Sleeping inside a smaller tent that is double-walled (ie. using a fly) and having decent ventilation to reduce moisture build-up are also tips worth bearing in mind.
Here’s hoping you can get a good night’s sleep, even on those freezing cold winter nights! With the above tips, you’re less likely to resort to the dangerous (and not recommended) tactic of using a heater inside your tent… or to the ancient Native American method of creating a hot rock bed!
Your sleeping bag is part of a whole sleep-system. Credit: Sea to Summit
Do you practice any of these tricks? Got any more to add? Comment below.
![David Leslie](https://cdn.snowys.com.au/blog/wp-content/uploads/ultimatemember/4/profile_photo.jpg?1724547895)
G’day! My name is Dave and there is nothing I enjoy more than getting out in the bush and enjoying the challenge and serenity of travelling around this beautiful country of ours.
After 6 years working as an Outdoor Ed Instructor, I’ve joined the team down at Snowys to help others get geared up and head to the outback!
As an enthusiastic photographer and freelance writer for 4WD Action magazine, I love to get out and capture God’s stunning creation and share it with the world.
After getting married at the end of 2010 and having our first child January 2012, I’m looking forward to seeing more of this beautiful country with my family.
Pingback: How to Sleep Warm When Camping – VentureCamping.com
I had a freezing night on the Overland Track and heeded some advice from the ranger on the second night. He suggested vigorous activity just before bed, then jumping inside with only a thinnish layer, and trapping your body heat in. The second night was much better.
I know people who swear by this method as well, Maggie! Extra layers don’t equal extra warmth, and with the right gear, less is more. Cheers mate
Thank you for your excellent, unique and original article. I’ve tried to locate clear information on this topic many times. You have helped make this interesting as well as clear.
Cheers David!
Great article, but just to clarify something, humans do not lose 30% of their body heat through their head (or feet , as many people believe). It is an urban myth, the rate of heat lose is roughly the same for all parts of the body. The head represents 10% of your body, therefore it loses 10% of your body heat
We certainly feel warmer with something on head, which I guess is half the battle of keeping toasty!
That’s really interesting Chris! Cheers mate
How do I wash my sleeping bag in a pillowcase? ??♂️
G’day Chris, if your sleeping bag is too large to fit inside a pillowcase, you could turn it inside out (zipped up) and wash on the delicates cycle in your machine. Alternatively, if your bag is filled with down, you might be keen to have a read of this blog for a few extra tips…
https://www.snowys.com.au/blog/wash-down-sleeping-bags/
Cheers
Put it in a duvet cover if it’s to big for a pillow case
Bought my goose down sleeping bag before heading off for a year’s backpacking around Europe in 1991. I cost me a fortune at the time but was bought for its minimal weight and size, as well as warmth.
It’s proved one of the best investments I have ever made in bedding or camping gear. It’s accompanied me across 5 continents and kept me warm in some truly remote locations.
It has been well used as a sleeping bag but just as regularly, unzipped, as a “travel” doona. I find the latter works if I do not need the full extent of its -4 mummy style insulation.
I’ve always used it in conjunction with a liner. Sometimes it wears a doona cover, when it gets used as such and gets stored, as per the origiinal instructions, unpacked on a coat hanger, so it is able to loft, rather than remain utterly compressed.
If using it as a doona, I do have to make allowances for its mummy shape, but, I’ve always made it work.
Stuffing it into its compression bag remains hard work; however compression bags have come a long way since the 1990s and I should probably investigate shouting it an updated compression bag, that is a bit more user friendly!
It is about to receive its first wash, before it moves into my camper van, to continue to serve me.
Guess my trusty sleeping bag is living proof that investing in quality gear and looking after it accordingly, is really worthwhile!
I have one I bought to take to Nepal in 1988 – I still get excited every time I use it and it is still in fabulous condition. Heavy, I suppose by today’s standards, but I love it and it was worth every cent. We use it as a doona in the camper as well. Mine is a Salewa I think.
I made the freezing mistake in getting too cold on my motorcycle and not taking off the waterproof liner and pants before getting into my -20c down sleeping bag in combination with a Exped winter 9cm down mat, as a result the bike gear prevented any warmth I could generate from warming the loft in the bag. It got down to only -3 and I was so cold all night thinking that my 25 year old down bag has lost it’s warmth.
The trick after some research is not to insulate the body from the bag but to allow body heat to warm the bag loft which traps the heat, and give your down bag a good shake when getting it out of the compression sack.
It’s a shame you had find that out from a freezing cold long night, but at least you know how to stay warm for the future, Rob – cheers!
Boil the kettle and fill up a hot water bottle, perfect for camping
Can’t go wrong with a tried and tested hot water bottle, Linda! Cheers.
A good sleeping bag will be EN rated but many people do forget that the EN testing is done with the use of and assumption that the mannequin/people are already wearing medium weight or winter weight thermals plus gloves and socks and a beanie.
So while adding warm clothing will boost a cheap bag doing so only allows a tested bag to achieve it’s rated minimum temperature. Also as we get older we do tend to need more sleeping insulation, it’s about 5C extra needed for every decade after 30 [ the EN testing assumes a fit and healthy young adult too] so my almost 70YO body will need a bag rated at -25C if I am camping in the Outback in winter where night time temperatures can drop as low as -12C These bags are very expensive An ultra lite synthetic blanket over the top or an overquilt is a great way to extend the temperature downwards, a synthetic quilt using 100GSM insulation can boost a bags rating by up to 10 degrees
Thanks for sharing your expertise Ted, especially about how you need extra insulation as you get older as that’s something a lot of people might not know – cheers.
You can pack you’re clothes that you are wearing the next day down near your feet as well. Also you can put your feet into a bag of some kind, if allowed you can make a heat shield with some green logs & direct fire back towards your shelter I’ve done this whilst it was the middle of winter & snowing on the Barrington tops national park in a swag for three week’s.
Do not eat a big meal. Your body will divert blood from your extremities to your GI tract to digest the food leaving your feet and hands cold. Drink a decent amount of hot water/broth/tea.
Put a hot water bottle in the sleeping bag an hour before you go to sleep. Nice and toastie!
The hot water bottle trick is a classic, and it’s the next best thing when you’re away from your electric blanket Vaughan.
Putting a decent layer between you and the ground makes such a difference. Having a ground mat or anything to line the tent floor under you helps. This goes for Under blowup mattresses too. It can get SO COLD otherwise.
Insulation is everything especially in those cold winter months, Rosie. 🙂
Foam mats are great under a blowup mattress, really insulation from the cold ground.
Agree, insulate your base to prevent heat loss.
if you are using a stretcher then placing a beach towel or even spreading news paper on the strecher can make a big difference.
And don’t forget to unpack your sleeping bag as early as possible to give it time to fully loft.
You’re on the money there Chippy, especially if it’s a down sleeping bag. Cheers!
Shake it out first too!
Make sure your store your down sleeping bag outside of its stuffsack. An intellectual friend of mine has failed to heed my advice on this and keeps it in the stuffsack. Perhaps he is not so intellectual. Keeping it stored loosely or fully stretched out under a bed means the down is more likely to retain its memory of being able to expand fully enabling it to loft more therefore providing greater warmth. If kept in a stuff sack the down and feathers can get crushed to the extent this memory is lost with minimal lofting and decreased thermal efficiency of the bag.
Well done to Snowys for providing these helpful articles and handy hints.
A down bag? Kept in its stuff sack? Definitely not the best way to do it that’s for sure!
Thanks for the compliment, we’re so glad you’ve enjoyed the tips in the article.
My sleeping bag is a good quality high performance one which packs down light and small for kayaking trips but in the freezing cold of the outback it was found wanting – so I bought an el cheapo $40 bag from Target – (packing small not a problem for the Prado roof rack), and I put my good bag inside the cheap one – that extra layer of trapped air between them working wonders – and I can open up the out side bag as needed when the nights are warmer. Predawn ice on the outside of my little tent but snug as a bug inside.
There is nothing better than feeling snug and warm when it’s icy cold outside, thanks for sharing your hack for making your sleeping bag warmer Trev.
These are all good tips. It is important to put new socks on at bed time, so wear tomorrow’s socks. This is because socks take up moisture from the feet and when that moisture evaporates, your feet will feel cold.
That’s an important distinction Meredith, we hadn’t thought of that but you’re right – clean socks are the way to go!
The dog is a great foot warmer if you have it with you! Haha!
A cute companion is almost better than a hot water bottle on a cold winter night 🙂
Foot warmer, sure mine tend to snuggle next to me. I was up in the Rockies in Colorado early spring, snow still on the ground. My two Samoyeds/with packs were more than content to be in the tent with me. They would typically sleep on both sides of me and I was as warm as sleeping at home.
I did leave the tent unzipped a bit cause of all the breathing.
Something I am surprised that no one mentioned, that I saw, was a bivy sack. I got one long ago so I did not have to set up the tent so often. The bivy sack will help a bit on the temperature if your not in a tent.
Best tip: share your sleeping bag with a furry friend!
Touché Sam – nothing like a friendly (and cuddly) portable heater to share your sleeping bag with. 🙂
Dogs actually have a higher body temperature than humans and whippets and greyhounds, higher again than other dogs. My whippet beats a hot water bottle and keeping him warm is as vital as keeping myself warm!
With that big meal, drink plenty of Port to stave off the cold, along with whatever other preferred tipple you may prefer.
As a bonus you may get to miss the early morning frost as well.
Assuming you made it to your sleeping bag.
The next day will be horrendous but you will sleep undisturbed.
Too right Glenn – a cheeky glass or two always helps send you off to sleep on a cold night!
Number 1 tip to keep warm is take your partner to bed with you. ????
Agreed! 😀