5 Toasty Tips to Make Your Sleeping Bag Warmer


Is your sleeping bag struggling to keep you warm in the winter months? Do you remember it being warmer – does it seem to have lost its warmth over the years? Or maybe you have a sleeping bag that’s better suited to the summer months and you’re about to head out in winter and don’t want to buy another sleeping bag? If this sounds like you, then read on for our 5 toasty tips for making your sleeping bag warmer.

Sleeping a sleeping bag next to dog

Brrrr, winter camping can get positively arctic if your sleeping bag isn’t warm enough! Image: Sea to Summit 

Here are a few tips on how to get more warmth out of your sleeping bag:

1. Wash your old 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 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 which prevents it from ‘fluffing up’ to keep 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 fluff up more effectively, thus trapping more warm air and increasing the insulation between the person inside the bag and the cold air outside.

Avoid adding extra blankets on top of your bedding as the weight will crush the filling, rendering it ineffective for trapping the air. Use them beneath you or under your mat instead.

An open washing machine that contains a sleeping bag and 3 tennis balls

Wash your sleeping bag to restore its warmth. 

How to wash your sleeping bag:

  1. Put your sleeping bag in a pillowcase to protect the thin outer material from tearing.
  2. Using a front loader, wash your sleeping bag on a warm, gentle cycle. (Remember to use Down Wash if you have a down sleeping bag.)
  3. Dry your sleeping bag in a large tumble dryer on its lowest setting. Place a few tennis balls inside the dryer as these will smash into the sleeping bag which will break up the filling and fluff it up again.
  4. If you don’t have access to a dryer, you can dry the sleeping bag on the clothesline in the sun. But every half an hour or so, beat it with a tennis racket to break up the filling.

A woman lies in her tent in a thermal liner and sleeping bag, reading a book

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. Image: Sea to Summit

2. Add a thermal liner and hot water bottle

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, consider adding a silk, cotton, or fleece liner rather than purchasing another sleeping bag.

There are many different liners on the market, with our favourite being the cotton and silk versions produced by Sea to Summit. A thermal liner is made of the same material as thermal underwear and is specifically designed and rated to boost the warmth of your sleeping bag.

By adding a liner to your bag, not only will you have a great combination for winter, but you can still use the sleeping bag on its own in average conditions, and then just the liner on its own when it’s really hot! A removable liner also keeps your sleeping bag cleaner, and thus, your filling in better condition.

If you’re heading away for a particularly cold weekend, it may be worth packing a good old fashion hot water bottle as well. Or you can use a regular water bottle, just make sure it has a quality seal so it won’t leak and you don’t want the water too hot. Sports style bottles aren’t a good idea but ones like a Nalgene or 360 Degrees Stainless Steel drink bottle work well.

Just heat the billy before bed and pour the hot (not boiling) water into your hot water bottle, then tuck it into your sleeping bag with you for some seriously snug comfort. Or even better if you prepare it ahead of time so you can pre-heat your bed before hopping in!

A man wearing a beanie and thermal top sits up in his sleeping bag inside a tent

Layer thermals under your clothes while you sleep. Image: Sea to Summit

3. Wear thermals

Thermal underwear is the warmest set of 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 very big difference to your comfort in cold conditions. Layering clothes on top of your thermal base layer will trap air between the fabric and keep you warmer than adding a single thick layer of clothing.

Make sure you add your layers and warm up by the campfire well before lights out so the heat has time to build and is easier to maintain since it will be trapped inside with you inside your sleeping bag once you do hop into bed.

A man lies outside in a sleeping bag, wearing a beanie and heating a kettle on a hiking stove

Keep your extremities warm on a cold winter’s day. Image: Sea to Summit

4. Put on a 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 can trap more warmth – just keep your mouth and nose free so you are not breathing into your bag which creates moisture throughout the night.

When your body gets cold, it takes blood away from the extremities such as your feet and hands, in order to keep it around your vital organs. By heading to bed with warm socks and gloves, you can keep your feet and hands warm and your body will keep the blood flowing to them, making for a better night’s sleep.

A woman preps food on a table next to a river

Tuck into a large dinner before bed. Image: Coleman

5. Eat a big dinner!

Your body will use a lot of energy to digest your dinner. All this energy will produce heat and keep you warm. By eating a decent sized dinner, and making sure it’s full of low GI carbohydrates, your body will keep burning fuel all through the night.

Two-minute noodles give you enough energy for 2 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! And contrary to popular belief, if nature calls during the night, you are better off surrendering to it as holding on will override your kidney’s signal to your brain and through a chain of technical temperature regulation measures, our bodies feel colder when our bladder is in need of relief.

A couple in their sleeping bags inside an open tent

Hopefully, this advice will help keep you snug while you sleep. Image: Sea to Summit

Keep warm on your next adventure

No matter how old or the quality of the sleeping bag you own, these tips will help you get the best performance out it, but a couple of other points worth noting are that your sleeping bag is part of a whole sleep-system, meaning that your choice of mat will also influence how cold or warm you’ll be throughout the night.

An airbed is not one to keep you warm as the air within the mattress will stay cold. Instead, choose a closed-cell foam or filled mat to trap air and help insulate. Sleeping inside a smaller tent that’s 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 and you won’t have to resort to the ancient Native American method of creating a hot rock bed or the extremely dangerous (and not recommended) tactic of using a heater inside your tent!


Do you practice any of these tricks? Got any more to add? Comment below.

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Joined back in December, 2011

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