No Extra Blanket? No Problem! Tips to Increase the Warmth of Your Sleeping Bag

Published on 06/02/2023 · 10 min readCamping Expert Jessica LaPolla runs through some easy tips for keeping your sleeping bag in tip-top shape and for keeping you extra warm on your next trip.
Jessica LaPolla, Camping Expert
By Camping Expert Jessica LaPolla

Photo by Stefan Schlumpf, courtesy of Deuter

Nobody wants to wake up in the middle of a cold night in a tent in the backcountry with chattering teeth. If you’ve been there, don’t worry, there are many different ways to enhance the warmth of your sleeping bag, both before and during your overnight adventures. In this article, I’m going to run through some easy at-home maintenance tips that every frequent camper should know for keeping your sleeping bag in tip-top shape, as well as a few tips and tricks to do while you're out camping to keep you extra warm on your next trip.

Sleeping Bag Maintenance

A well-kept sleeping bag is a warmer sleeping bag! Just like with any outdoor gear, the life of your sleeping bag, and its functions increases when it is properly cared for. At home, it is important to regularly assess the condition of your bag. Is it fluffed up? Insulation, such as down, only works if the loft is intact and fluffy. Luckily, sleeping bags are machine washable. If your bag seems to be flattened or you notice dirt or sand on it, just put it in a pillowcase to protect it and send it through the wash on a gentle cycle. If you have a down-fill bag, make sure to use a special down shampoo or wash and tumble dry it on low with tennis balls.

Does your sleeping bag have any wear and tear? Patch up any holes where stuffing could escape. When putting your sleeping bag away in storage between uses, take it out of its stuff sack and leave it open and fluffed up, so that it isn’t constantly being compressed and flattened.

What to Wear in your Sleeping Bag

Now, let’s discuss a few practices to use while you are camping or backpacking. To understand how to increase the warmth of your bag, you must also understand the function of a sleeping bag. Sleeping bags keep you warm by trapping and radiating your body heat. This is why wearing dry base layers, long johns, or long underwear inside your bag is most effective. Opt for Merino wool over synthetic fabric; it will keep you warmer and it doesn't hold onto odor, so you'll stay smelling fresh for way longer.

Wearing extra layers and clothes is also not recommended because it could compress parts of your bag, reducing the insulation qualities. It could also make you sweat if you get too warm, and you may not notice that you are sweating until after it's too late. Wearing damp clothes can trap moisture and compromise the insulation of your bag. Make sure your base layers are well fitted, but not too constricting. Clothes that are too tight may restrict blood flow, making you colder. Keep your extremities warmer by wearing good socks and if needed, gloves.

Maximizing the Efficiency of your Bag

When you set up camp and you pull your sleeping bag out of its compression sack, let it fluff up completely before crawling inside. If your bag has a continuous baffle, you should shake it out to distribute the stuffing evenly. If you’re really in a cold pinch, shake the bag so that more of the insulation distributes around your core. This will help keep you warmer at night. You might think it’s a good idea to add a camping blanket or camping quilt over the top of your sleeping bag, but this should be avoided. Putting any blankets or jackets over your sleeping bag will compress it and it will lose some of its ability to insulate and keep you warm.

More Tips to Maximize the Warmth of your Bag

Photo by Stefan Schlumpf, courtesy of Deuter

Avoid Heat Escape

Standard sleeping bags come with a temperature rating, which gives you an idea of what the lowest temperatures you can comfortably sleep in are. While there is some variation based on women versus men, cold sleepers versus warm sleepers, and plenty of other factors, the temperature rating can at least give you an idea of the warmth the bag will provide.

In addition to the insulation you expect in a sleeping bag, some sleeping bags have special features to enhance warmth, such as a hood, a drawstring, or a draft collar. If your sleeping bag has a hood, which many mummy sleeping bags do, close it around your head and face as much as possible to minimize any cold air seeping in (use the drawstring for this, if there is one!). If your bag doesn’t have a hood that you can draw closed, wear a beanie or a balaclava to keep the heat from escaping from your head. Make sure that the zipper on your bag is all the way closed to minimize any draft.

Create Warmth

Another useful trick to make sure you stay as toasty as possible is to use a hot water bottle. You can fill your water bottles with boiling water before bed and put them in your sleeping bag. While you may be tempted to put your hot water bottle at the bottom of your sleeping bag to keep your feet warm, the best place to put it is near your core! Even more specifically, placing the hot water bottle between your legs near your femoral artery will circulate warmth throughout your body. Put the water bottles inside a dry sack or bag in case they leak. This will also ensure that you have plenty of unfrozen water for the next day! But if you’ll be camping in freezing temperatures, make sure you bring wide-mouthed bottles; these are less likely to freeze over.

Eat

Make sure to eat a calorie and fat-rich dinner an hour or so before bedtime. This will give your body the energy it needs to stay warm. Eating right before you go to bed though could actually make you colder, as your body will be using energy to digest food at first, not keep you warm.

Sleeping Pad

Sleeping pads are one of the primary providers of warmth when camping in the cold, and are a key component of your sleep system! While many people think a sleeping pad's purpose is to provide comfort by way of cushioning from the hard ground, it's also to provide warmth by way of insulation from the cold ground. And even on a warm night, the ground can still be cold!

Look for a sleeping pad with a higher R-value, which is the measurement used to tell you how much insulation the pad will provide. Or, use two sleeping pads! If you use a basic air pad or air mattress with a low R-value, it will not provide you with enough insulation to keep you warm. Even in warm weather and air, it can cause your temperature to drop. Good sleeping pads will not only make you more comfortable but can keep you warmer.

Tent Selection

Make sure your tent is appropriate for the season in which you are camping. A three-season tent is not meant to withstand harsh cold, high winds, or the weight of snow falling, and in extreme situations, could actually suffer damage or be destroyed by weather conditions. If you have a tent that is not made with mesh or breathable materials, then don’t zip your tent completely, even when it’s cold. That’s right, it may sound counterintuitive, but unzipping a small portion of your tent will allow for ventilation, decreasing moisture and condensation build-up inside the tent and allowing you to stay much warmer!

Pee (Before Getting in Your Sleeping Bag)

Empty your bladder right before you go to bed. This will ensure that your body is not wasting energy holding the urine within your bladder at a certain temperature, and it also prevents you from having to leave your bag or tent in the middle of the night. If you do wake up in the night and have to pee, go do it! Or if you regularly wake up in the night to pee and you know that going outside in the cold is not going to happen, keep a pee bottle in your tent so that you don’t have to go outside. Just empty it away from camp the next morning!

Exercise

This tip is not going to sound like fun, but another way to make sure you sleep warmly and soundly is to do some light exercise before you climb into your sleeping bag at night. Some jumping jacks or push-ups will get your blood pumping and your body temperature up, so when you get into your bag, excess heat will radiate off of your body, allowing your sleeping bag to do it's job and trap heat, and keep you warm right from the start. Just don't do too much exercise that you start sweating!

What if the Temperature Is Way Colder than I Expected?

Photo by Cast of Thousands

You set out on an overnight trip with your sleeping bag that is rated to 20°F. However, it becomes much colder than you anticipated, dropping down to about 15°F that night. Now, you’re not going to get frostbite, but you’re probably going to be chilly. There are a couple of things you can do here:

  • Use a Thermal Sleeping Bag Liner, such as the Sea to Summit Thermolite Reactor Fleece Liner. There are silk liners, cotton liners, and fleece liners, and they each can increase the warmth of your sleeping bag by a few degrees, giving you a colder lower limit. They are typically lightweight and compact, and some even fall into the "ultralight" category weighing just a few ounces! So if you think there’s a chance that the temperature will decline, throw it in your pack and bring one along for peace of mind. When purchasing a sleeping bag liner, just make sure it is the same shape as your sleeping bag—a mummy liner won't fit on a rectangle bag very well!
  • Use a Vapor Barrier Liner. If you know you’ll be camping in extreme weather and it becomes much colder than you are prepared for, utilize a vapor barrier liner. A step up from a regular thermal liner, these are not very comfortable and will make you feel clammy, but they can increase the warmth of your bag by quite a bit and will keep you from freezing.

Final Thoughts

If you are looking to buy a new sleeping bag that will be durable for cold weather camping and will maximize warmth, look for a high-fill down insulation (800+) bag that is a mummy shape with a hood and draft collar. A sleeping bag made of synthetic material is not a bad option, but synthetic insulation is typically heavier and bulkier than down-fill. And while synthetic bags do have advantages over down in wet or damp climates, on a night with temperatures below freezing, you will want the extra warmth that down-fill provides. Ideally, make sure it has a box or continuous-baffling system and, to really go all out, select one with an overstuffed foot box to keep your toes toasty.

Whether you’ll be camping in the summer in the mild, warm air, or in sub-zero Arctic temperatures, be as prepared as possible by taking care of your sleeping bag. Regardless of if you are using an ultralight sleeping bag that you plan to hike for miles with on your back or if you are using a bulkier bag that's ready for your next car camping adventure, keep in mind the key features that will help with warmth and the tips and tricks mentioned above to stay cozy! Make sure you take a sleeping bag that is rated appropriately for the expected temperatures, and bring a liner to increase the sleeping bag's warmth if you expect it could be colder. And if you have any questions about finding the right sleeping bag for your next adventure, reach out to me or one of my fellow Camping and Hiking Experts here on Curated for free, personalized advice. Happy camping!

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