I know it’s spring, and I was a little behind in getting the snow shelter posts out, but after all those posts on snow shelters, I thought it a good idea to write about sleeping warm before I start in on warmer weather shelters. Sleeping warm is a key any time of the year, and just because it’s springtime doesn’t mean it can’t get cold out there.
Sleeping warm is one of the key factors that can make or break an adventure. Remember the body cools down during sleep, and the blood is drawn from the extremities (feet and hands) to the center or core of the body, so proper insulation must be provided to prevent heat loss. For a good night’s sleep on your next adventure, you may choose to use some or all of the tips below.
1. Keep Hydrated
Hydration is key to proper thermal regulation for the body, so keep hydrated during the day (dehydration is more common in the cold than in hot weather). But, avoid drinking lots of fluids at night so you won’t have to keep getting out of your sleeping bag and dropping your temperature to go to the bathroom.
2. Use a Pee Bottle
If you must go, use a pee bottle. It’s better than exposing yourself to the elements by climbing out of your shelter and dropping your temperature even more. Besides, holding it in requires your body to waste energy (i.e., calories) trying to heat the water in your bladder to 98.6 degrees.
3. Eat a Big Dinner
Eat a big dinner with lots of calories, preferably fats and proteins. During the day, carbohydrates are good for quick energy, but they burn up to fast to last throughout the night. Remember, calories are a unit of heat; without them, the furnace won’t burn hot.
4. Keep Snacks
Keep a snack with you so you can replenish those lost calories if you wake up cold in the middle of the night.
5. Go to Bed Warm
Warm-up by taking a brief hike around camp or doing some jumping jacks. If you wrap a frozen salmon in a sleeping bag, it will stay frozen because your sleeping bag is an insulator for cold or heat, just like a thermos. So go to be warm, and it will insulate the warmth.
6. Select a Protected Site
Suppose you can select a protected site out of the wind and off the valley floor and other low areas where cold air settles. A good rule is to try and be 75 feet above the valley floor.
7. Fluff Up Your Sleeping Bag
Suppose you have one fluff up your sleeping bag with vigor to gain maximum loft before climbing in for bed. Loft creates dead air space, which is where the heat is captured.
8. Insulate Yourself from the ground
Use a good insulating pad between you and the ground. Research shows that what you have under you is more important than what you have over you for warmth.
9. Wear a Stocking Cap
Where a stocking cap to bed, you lose most of your heat through your head.
10. Don’t Breath Inside Your Sleeping Bag
Keep your nose and mouth outside your sleeping bag. Your breath contains a lot of moisture, reducing your sleeping bag’s insulating value.
11. Cover Your Mouth at Night
One of the ways we lose heat is through respiration, along with moisture loss in cold, dry air. That’s why you see steam coming from your mouth when you breathe in cold weather, and we’ve already pointed out how hydration is important. So, wear a balaclava or wrap a scarf around your face, and you will not only prevent some dehydration but also conserve heat.
12. Roll the Moisture Out of Your Sleeping Bag
Roll moisture out of your sleeping bag each morning (roll from foot to head). Then leave it open until it cools to air temperature, and if weather permits, set it out to dry in the sun.
13. Use a Layered Sleeping System
Use a layered sleeping system (i.e., sleeping bag, liner, half bag, and bivy sack). A layered system helps remove the frost build-up that naturally occurs when your body heat meets the cold air outside the bag.
14. Avoid Overheating
Avoid overheating at night, and make sure you go to bed dry. Overheating produces perspiration, so vent your bag if needed or take off your stocking cap.
15. Make Sure Your Feet Are Dry
Make sure your feet are as dry as possible before going to bed. This can be done by having a pair of dry sleeping socks or polar guard booties in your bag for sleeping only.
16. Use a Sleeping Suit
Use a sleeping suit and a clean and dry pair of long underwear stored in your sleeping bag for sleeping only.
17. Wear Loose Fitting Clothing
Please wear loose-fitting clothing to bed, so it doesn’t restrict circulation.
18. Stay Clean
Keep your sleeping gear clean. Dirt clogs air spaces in material and reduces insulation value.
19. Use a Hot Water Bottle
Fill a water bottle with boiling before you go to bed, and then strategically place it in any cold spots. Just make sure it has a screw-on lid like the Nalgene bottles (one bonus is that you have some water ready to go in the morning, instead of having to melt snow first thing). A variation is to use disposable heater packs or hand warmers if you have them (I like to put them in my boots, so they’re warm in the morning when I first put them on and use the water bottle for my bag). In the old days, they would take a rock from around the fire and place it in an old sock. You can still do this, but with the modern synthetic fabrics, you need to be careful not to melt everything.
20. Use a Half Bag
If you have cold feet, sleep with your feet together in a half bag or a bag that pulls up over your feet and legs (you could also use a fleece jacket or sweater) inside the sleeping bag. A half bag uses the principle of the buddy system, where the feet share heat instead of being isolated, much like mittens are warmer than gloves because the fingers are together.
21. Use the Buddy System
Speaking of the buddy system in the last one, you can use the buddy system. Two people spooning (i.e., lying together side by side like spoons in a drawer) are far warmer than one by themselves. It’s probably the oldest method of warm sleeping, and shyness loses its power in a true survival situation.