Gone are the days when I sleep in a cold tent and feel refreshed in the morning. If you are like me, you want to stay warm at night. So, I set off to investigate a better way to stay warm in my tent.
My suggestions are simple but there is some science behind it. If you are new to backpacking, learning these 15 ways before your first backpacking trip makes you more comfortable when evening arrives. Here is what I found. Scroll to read my reasoning.
15 ways to heat your tent without electricity:
- Use a mylar blanket
- Use a foam mat below your sleeping pad
- Do light exercises before bed
- Use a sleeping bag cover
- The old fashioned hot water bottle
- Eat a high-calorie meal
- Use a balaclava
- Heat rocks
- Use hand and feet warmers
- Use a candle (but be careful)
- Cuddle up buttercup
- Low-temperature sleeping bag
- Use a moisture absorber/ dehumidifier
- Bring the dog along
- Use a tent-safe heater (well, kind of cheating!)
While these are super simple, let’s take a closer look. Pretend for a minute that you are Bill Nye, the Science Guy, and want to learn more about body heat.
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What principles are in effect?
To understand heat, you must learn what it is and what it is not. Heat is a form of energy and not a physical substance. Meaning, it has no mass and can move around freely. Heat is the exchange of thermal energy (heat) between physical systems.
There are three ways heat is transferred; 1. Conduction, 2. Convection, and 3. Radiation.
When heat is heat is transferred from one solid surface to another it is known as conduction. Think about when you grabbed a chocolate bar and it melted in your hand, or when you turned on your camp stove and put a pot on to heat it. The heat energy is transferred from one surface to another (hand to chocolate and stove to the pot).
Convection is when the heat from a liquid is transferred through the liquid speeding up the water molecules. As the water molecules speed up they move apart and eventually become water vapor (water in gas form).
For example, when the sun beats down and heats the ocean water it speeds up the water molecules causing them to move apart. The heat in the water is transferred within the liquid causing the water to turn into gas. This is convection.
Radiation occurs when the heat is transferred via electromagnetic waves. What this means is that heat travels in waves away from the heat source. Like for example a candle. The flame heats the air around it and ‘radiates’ through the air to heat nearby objects.
How these principles are at work with our examples
To better understand our situation, let’s take a look at each item on our list and see what form of heat energy is taking place. This will help us know how to choose the best way to heat us when sleeping in our tent.
1. Mylar blanket – radiation
Our body radiates heat away as a way to cool us during hot days. However, our bodies start losing heat when the outside temperature drops below 68 degrees Fahrenheit.
A mylar blanket helps to reduce this heat loss by reflecting the radiated heat towards our bodies. Therefore, less heat is lost away from the body and out of the proverbial window.
A word of caution: Mylar blankets are effective when you keep them somewhat loose by wrapping them around your body. By creating an air pocket between the blanket and your body, the heat gets reflected into the air space. However, if you lay on the blanket and lose this air pocket, then the blanket becomes a conductor of heat and pulls heat away from your body.
2. Foam mat – conduction
While the mylar reflects heat, the foam mat retains heat. The heat held in the foam mat is transferred to our bodies by way of conduction. For example, it is well known that ‘memory’ foam mattresses get very warm. Again, your body radiates heat and the foam collects this heat. By lying against the foam we benefit from conduction back to our bodies.
3. Do light exercises – conduction/ convection/ radiation
Wow, we hit the trifecta! But how does our body transfer heat in three different ways? Well, to be honest, most heat is transferred in a couple of different ways most of the time.
But here is how we transfer heat in all three ways when we exercise. First, when we contract our muscles (arms, legs, and heart muscles) they produce heat and transfer that heat to the surrounding tissues. Our heart pumps the warmed up blood throughout our body supplying the tissues with warm fluid. This is by way of conduction.
Next, our body sweats, and liquid is turned into a gas to escape into the surrounding air. Ta da, convection! The newly warmed air stays in the tent thereby increasing its temperature.
Finally, our skin radiates warmth electromagnetically into the air. This warms the surrounding air. Radiation.
As you can see, this requires energy from our own body and therefore isn’t something you can do all night long. Unless of course, you are shivering.
4. Sleeping bag cover – traps heat
A sleeping bag cover helps to store heat between you and the cover. So, after you do a few pushups and crunches the heat is collected and remains close to you. So, in reality, it doesn’t transfer energy.
5. Hot water bottle – conduction/ radiation
For all the Millenials out there a hot water bottle is a rubber or plastic bottle with an inner pouch that holds hot water. The water remains hot for a very long time, like overnight. So, if you sleep with a bottle next to you the heat conducts from the bottle to your skin (clothes/skin). When the bottle is a few inches from your skin then the heat from the bottle radiates to you.
These bottles were used more extensively years ago to help people stay warm and sleep in their homes. The homes weren’t as insulated from the cold temperatures as they are now.
6. Eat a high-calorie meal – conduction/ radiation
Similar to exercising, eating a high-calorie meal increases overall body temperature. This is conduction at work. Also, the extra heat makes its way to the skin and radiates from the body.
A word of caution, I have always had difficulty sleeping after a big meal at night. So, if that is you, maybe use a different means of heating yourself.
If you don’t want to cook after hiking, Greenbelly makes super tasty meals with loads of calories. The meals are great for the weekend and weeklong trips and heat you at the end of a long day.
7. Use a balaclava – traps heat
Clothing for the most part is used to trap and store heat. Unless you are using electric socks, our clothing does not provide heat energy to us. It just uses what we provide and keeps it up against us. A balaclava when up against our skin helps with conduction, and when loosely fit, helps radiation do its thing.
8. Hot rocks – radiation
Be careful with this one. Some rocks when heated will fracture and this could cause injury.
With that said, rocks when heated by the fire hold their heat very well and for a lengthy period of time. The heat radiates into the air and provides warmth. Hot rocks provide warmth on a cold night. Just be sure to use a t-shirt or towel between you and the rocks.
9. Use a candle – radiation
Let’s get controversial for a moment. Candles emit radiated heat and when placed in a small area like a tent raise the temperature inside the tent. Studies have shown that candles in tents have the ability to raise the temperatures as much as 15 degrees on super cold days.
But, let’s be real for a minute. Only try this if you are staying awake while the candle is burning…and only when you are in a super cold situation.
10. Hand and foot warmers – conduction/ radiation
Buckle up. From Wikipedia: “Air-activated hand warmers contain cellulose, iron, activated carbon, vermiculite (which holds water) and salt. Hand warmers produce heat from the exothermic oxidation of iron when exposed to air. They typically emit heat for 1 to 10 hours, it usually takes 15 to 30 minutes to start to heat up.”
Not so bad, right? Basically, a chemical reaction happens where the iron meets the oxygen and reacts to form rust. The salt is used to help speed up the process. Like most chemical reactions, heat is released during the process.
You use the warmers up against your hands and feet to provide conduction of heat from the pouch to your hands or feet. Also, the pouches provide a small amount of radiated heat helping keep your hands and feet warm.
11. Cuddle up buttercup – conduction
Depending on the social situation, cuddling up is an appropriate way of keeping warm. My wife and I have tents that zip together. This way, we just cuddle up and provide warmth for each other. Cuddling up next to someone uses conduction heating with a skosh of radiant heating.
12. Low-temperature sleeping bag – traps heat
A sleeping bag is simply a way to trap the heat created by your body, hot rocks, etc. Sometimes in colder conditions, I use a tent that is rated below what we expect for the night. The reason I do this is to retain as much of my body heat as possible early in the night. As the temperature drops, my body heat drops with it.
As long as I start warm enough then I can maintain warmth throughout the night. I find that if I don’t do this I am super chilled in the morning.
13. Moisture absorber/ dehumidifier – dries the air
Portable moisture absorbers are fairly inexpensive and they reduce the humidity within the tent.
So, why am I colder when it is more humid. Well, when the temperature is cold out and the humidity is up, the body conducts heat more quickly and easily away from the body and we get colder as a result.
14. Bring along a pet – conduction
Fido is more than just a companion, he is a small stove on a cold night. Just like cuddling up, your dog provides conductive heating as well as a small amount of radiant heat.
As an aside. Pets make for an early warning system. However, make sure that Fido doesn’t startle easily or you could be in for a long night of barking.
15. Tent-safe heater – radiation
A tent-safe heater does a great job radiating heat from the body of the heater into the air. We benefit from this transfer of heat only when close to the heater. Because our tents are not very large in the grand scheme of things, the heat stays in the tent to provide long-lasting warmth.
Unfortunately, the very tents that keep us warm lose heat through the tent walls. So, the heater needs to run throughout the night.
Putting it all together
When it comes down to it, we use several heat sources to sleep. Also, we rely on good backpacking gear to hold our heat close to our bodies. Understanding how heat is created, maintained, and utilized goes a long way to keeping us safe when out in the wilderness.
How to prepare for bedtime
If you want to stay warm when sleeping in a tent it starts with preparation. Here are some suggestions. When preparing for bed, change completely out of your hiking clothes, especially your socks. Then change into clean, dry clothes, socks, and a beanie hat. If it is super cold then maybe add some gloves. Now you are ready to hit the hay.
How do you keep a tent from getting too hot?
While staying warm appears to be more important, keeping cool at night is also important. Think about a time that you tossed and turned on a warm summer night. Sweat rates are up and you start the day in a somewhat dehydrated state.
A few tips to keep you cool when sleeping in your tent. First, wear light, breathable materials against your skin. This helps to wick perspiration from your skin and cool you off.
Second, keep your sleeping bag open. Meaning, don’t zip it up but use it as you would a blanket. You won’t hold in the heat and humidity escapes from the bag.
Third, open your tent windows. This might sound like a common sense tip, however, it is generally cooler at night so, I have forgotten to open the vents. This leads to a very warm tent when the sun comes up in the morning.
Finally, remove the fly from the tent. This is risky though. If you are sure there is no rain on the way then this is an option. The breeze helps dissipate heat.
Bonus: dehumidifiers and moisture absorbers help remove humidity and make it easier for perspiration to evaporate. Evaporative cooling happens when perspiration evaporates and heat floats away from the body with the water vapor. A humid atmosphere prevents sweat from evaporating.
A word about winter backpacking
Recently, we wrote an article about winter tents. Using the tips in this article coupled with the information about winter tents is a win-win situation. Check out our winter tent post.
Stay warm and enjoy the outdoors!