10 Pro Tips For Staying Warm in a Sleeping Bag

By Michael Lanza

Head into the mountains in summer, or almost anywhere in fall or spring, and you can encounter nighttime and morning temperatures anywhere from the 40s Fahrenheit to well below freezing. That’s more than cold enough to pose a real risk of hypothermia or, at the least, result in a miserable night for you or a partner or child you’ve taken backpacking or camping—and would like to take more. Here’s the good news: The very simple techniques outlined in this article can turn a potentially unpleasant night into a comfortable one.

Countless frosty nights sleeping outside over the past three-plus decade—including many years as a past field editor for Backpacker magazine and running this blog—have taught me a few things about how to stay warm. (My coldest night was -30° F, in winter in New Hampshire’s White Mountains. I don’t recommend it.)

No matter how easily you get cold when sleeping outside, or whether you’re camping in the backcountry or at a campground, these 10 tips will keep you warmer on cool and chilly nights in your sleeping bag.

Tell me what you think of my tips, ask any questions, or share your own tips in the comments section at the bottom of this story. I try to respond to all comments.


Hi, I’m Michael Lanza, creator of The Big Outside, which has made several top outdoors blog lists. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here to learn how I can help you plan your next trip. Please follow my adventures on Facebook, Twitter, Instagram, and Youtube.


 

#1 Clean Up

At the end of each hiking day, wash the dirt and dried sweat from your body; the latter can act like a heat conductor, chilling you, and getting a bit cleaner will just make you feel better. Swim in a lake, wade into creek and splash water all over yourself, or at least wet a bandanna or other cloth (or use wet wipes or other such products) and wipe yourself off.

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The Nemo Kyan 20 synthetic sleeping bag.
The Nemo Kyan 20 synthetic sleeping bag. Click photo to read my review.

#2 Change Into Dry Clothes

Damp clothes promote conductive heat loss from the body. Change into dry clothing to sleep, as opposed to the clothes you sweated in while hiking.

#3 Dress Smartly

Inside your bag, wear a hat, socks, and extra layers on your body, but avoid putting on so many layers that you isolate your core, which is your body’s furnace, from your extremities, which get cold more easily. It’s often more effective to wear just one or two light to midweight base layersthat are highly breathable, so as to allow your core’s heat to disperse throughout the bag. If you need more warmth, lay an insulation piece over your torso and hips inside the bag, essentially boosting the bag’s insulation, and stuff other extra clothing around you or at the foot of your bag to provide added insulation for your entire body.

Feathered Friends Hummingbird UL 30.
The ultralight but very warm Feathered Friends Hummingbird UL 30. Click on the photo to read my review.

#4 Use a Hot-Water Bottle

Stick a water bottle (like a plastic Nalgene bottle, not an insulated or vacuum bottle, which would not release any heat) filled with hot water in the foot of your bag. If that’s not enough, put a second bottle filled with hot water in the middle of your bag. (Make sure they’re sealed tightly.)

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#5 Sleep on Insulation

Use an insulated pad or air mattress rated for the lowest temperatures you expect to encounter. Mats and pads with an R-value of between 3 and 4 are intended for three-season temperatures—generally, above freezing—while those with an R-value of over 5 are intended for use on frozen ground in below-freezing temperatures. If needed, add a second foam pad under your primary air mat if you’re sleeping atop frozen ground or snow.

Therm-a-Rest Hyperion 32F/0C sleeping bag.
The one-pound Therm-a-Rest Hyperion 32F/0C sleeping bag. Click on photo to read my review.

#6 Augment Your Sleeping Pad

If you’re using a short air mattress or foam pad (to save weight in milder temperatures), lay your empty pack beneath your feet to insulate them from the ground, which can drain heat from your body even in summer. Or bring a short foam pad to provide more padding and insulation under a full-length air mat.

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A backpacker at a campsite on the Teton Crest Trail in Grand Teton National Park.
Todd Arndt at a campsite on the Teton Crest Trail in Grand Teton National Park. Click on the photo to see more images from that classic trip.

#7 Pile Extra Clothing Underfoot

Your feet get cold more easily than other body parts because they lie the farthest from your heart and, inside a sleeping bag, are not close to your furnace: your body’s core. They can also get cold because the ground under your sleeping pad is cold. Pile extra clothing under the foot end of your bag to give your feet more insulation against the cold ground.

#8 Use a Bag Liner

Use a sleeping bag liner, which can add the equivalent of several degrees of warmth rating to a bag.

Never get cold again (well, almost never). See my “5 Tips For Staying Warm and Dry While Hiking.”

 
The Sierra Designs Nitro 800 20-Degree sleeping bag.
Testing the Sierra Designs Nitro 800 20-Degree in the Wind River Range. Click on photo to read my review.

#9 Eat Some Fat and Sugar (The Fun Tip)

Eat a snack high in fat right before bed, like a candy bar, and have a hot drink with sugar in it, like hot cocoa. Both will fuel your body’s furnace through the night.

#10 Use Your Partner

If you’re sharing a tent with a partner who doesn’t get cold as easily as you, ask that person to sleep on the tent’s windward side. If you have two warm-sleeping partners, sleep between them, or at least position your bags and pads close together to benefit from one another’s body heat.

Tell me what you think.

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See my “Pro Tips For Buying Sleeping Bags” and all of my reviews of sleeping bags, air mats, and backpacking gear that I like.

Whether you’re a beginner or seasoned backpacker, you’ll learn new tricks for making all of your trips go better in my “12 Expert Tips for Planning a Wilderness Backpacking Trip” and “A Practical Guide to Lightweight and Ultralight Backpacking.” If you don’t have a paid subscription to The Big Outside, you can read part of both stories for free, or download the e-guide versions of “12 Expert Tips for Planning a Wilderness Backpacking Trip” and the lightweight backpacking guide without having a paid membership.

 

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21 thoughts on “10 Pro Tips For Staying Warm in a Sleeping Bag”

  1. +40 years recreating and rescuing others in Wyoming winter mountains. I thankfully still have my fingers and toes using lighter fluid type pocket heaters (zippo). They last for up to 10 hours and are bombproof. Mother Nature WILL spank you if you are stupid in the cold.

    Reply
    • Thanks for the good suggestion, Rak. In my experience, people often make mistakes in the backcountry not because they’re stupid but because they’re inexperienced or uninformed in some skill or environment, and sharing information is, hopefully, the way to avoid bad outcomes.

      Reply
  2. Great article and all good comments. My additional go to: Load your coffee pot up the night before with water and coffee in case your water you may have left at less than 32 degrees freezes. And yes, that has happened to me and it is not a happy morning sight.

    Reply
    • Tip #9, eating before going to bed… while the rare occurrence likely will have no observable effect, please Google and reference articles discussing the effect of sugar and digestion time lapse upon the brain as relates to Alzheimer’s and dementia.

      As always, thank you for your articles and insights, helps me get through the day while waiting for the next opportunity to visit The mountains.

      Reply
      • Thanks, Edward, I’m honestly not familiar with any research or data behind sugar, Alzheimer’s, and dementia. I’m simply suggesting that consuming fat before bed when camping in sub-freezing temps has always given me a long-lasting boost in warmth, much as consuming fat boosts warmth and energy when I’m active during the day in sub-freezing temps.

        Reply
  3. Michael,

    Great tips. A few that work for me. I carry wet ones for clean up, especially when it is cool/cold or at elevation. I carry down booties for those same conditions. They are light but great warmth.

    When buying a bag make sure it is not too tight fitting because it is more difficult to use a liner or add layers. Or too large as there is too much space to warm.

    Head wear can vary from light, medium or heavy. Same with liners.

    For cold trips take a pee bottle. Make sure it is marked or an unique shape. Close it tight.

    If you can, shift your down (if you have a down bag) to the top and sides. When you lay on the down it compresses loosing most of its insulation value. Better yo use that second pad, clothing, your empty pack, etc that you recommend underneath.

    Avoid or minimize the amount of condensation. Similarly avoid/minimize perspiring. Moist down does not insulate as well. Also, dry your bag whenever you can. Even in cool/cold weather keep your tent ventilated.

    Cheers

    Reply
  4. So I have a crazy-pants tip to add to the list I swear had worked for me: No matter how cold and uncomfortable it is outside, make sure to completely empty your bladder before going to sleep. If you need to go in the middle of the night, do it. Don’t hold off until morning.

    My pseudo-science theory as to why this seems to work: instead of your body working hard to keep all that pee at a toasty 98 degrees, it can use that energy to keep the rest of your bits warm.

    Take it or leave it . But I’ve decided a few seconds of cold booty is worth hours of greater warmth in my bag.

    Reply
    • Thanks, Jes. I first heard that tip years ago. I’ve debated it with friends who have science backgrounds and insist that the body would not burn any more energy heating urine that’s inside the body that’s at body temperature, anyway. My take is that staying well hydrated certainly helps keep you warm, and I relieve myself right before bed in hopes of not having to get up during the night; but if I have to, I do get up, because it’s hard to sleep otherwise. Keep a warm puffy jacket handy to slip on if you have to get up.

      Reply
  5. I use Coleman Trinidad warm weather sleeping bag (http://campingandcamping.com/coleman-trinidad-sunridge-warm-weather-sleeping-bag-review/) for my summer camping trips.

    For colder weather I have two more sleeping bags. One is a 3-season sleeping bag, another one is a 4-season sleeping bag.

    There is definitely no need to spend 300 or 500 USD for a summer sleeping bag. Don’t get fooled by the “amazing features”. A warm weather sleeping bag can be as simple as it can be…

    Reply
  6. I usually don’t have much of a problem staying warm since I use a nice down bag, but our kids, 4 months and 2.5 years get cold. We usually try to have them sleep near mom and haven’t stepped out to get them their own little bags yet.

    Reply

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