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How to keep warm at night in a bivouac ?

Being cold at night at home is not very annoying. You wake up, get up, and go get an extra blanket. But when it happens while camping, it becomes more troublesome. At best, you just have a terrible night without closing your eyes for a second, and at worst, it can lead to hypothermia. To avoid this kind of situation, here are 10 tips to keep warm at night during your hiking camps:


1. Eat well before going to sleep

Skipping a meal is never a good idea, especially during physical activity. The body needs fuel, and eating well is essential, even at night while resting. This will allow your body to continue functioning normally and, in particular, produce heat.

But beware, eating well does not mean overeating! The digestive system would consume about 10% of the energy over a whole day. Eating too much is too demanding for the body, which would focus on this task instead of warming you up.

Finally, if possible, try to eat hot meals. The most common choice during hiking is freeze-dried meals. It's comforting and nutritious after a day of effort. Besides, the warmth of the food can help warm your body.


2. Drink tea and pee!

Hydration goes hand in hand with nutrition. It is just as important. We won't talk about staying well-hydrated during the day; you know the drill. But before sleeping, it is also important. A dehydrated body does not function properly. Once again, your body has to compensate and only partially fulfills the function of warming you up.

After your meal, it can also be beneficial to drink a hot beverage. It can be coffee or tea if caffeine and theine do not prevent you from sleeping. Otherwise, an herbal tea will do just fine. The cup will warm your hands, and the drink will warm your body.

Like with food, be careful not to drink too much. The risk is needing to urinate at night. You then need to, at a minimum, get out of your sleeping bag if you have the right accessories to do your business in the tent or otherwise leave the tent. In both cases, your body will cool down. So, it's a bad idea.

Speaking of needs, it is important not to wait until you need to urinate. This is a well-known tip among hikers: go pee before sleeping. Otherwise, the body will consume a lot of energy. Energy that it will not use to warm you up.

3. Shelter well from the wind

This is especially true if you sleep in a hammock or under the stars. It seems logical, but avoid exposing yourself to the wind. To do this, either opt for a natural shelter with a windbreak like Robinson Crusoe with branches and leaves. Otherwise, trees or a wall will also do the trick. In the case of camping on snowy peaks, the most experienced among you will build an igloo.

Otherwise, there is the tarp. It is a paid solution but brings a lot of comfort. A tarp is a sheet that protects from both rain and wind. If none of these options suit you, the tent is obviously suitable. It is waterproof and blocks the wind. But you will have to carry it on your back during the day.


4. Have an insulating mattress

The mattress is not only intended to provide comfort. It also aims to insulate you from the cold. It is not the mattress that will warm you up, let's be clear. However, it will prevent you from getting cold. Contrary to popular belief, the cold mainly comes from the ground and not the air. An inflatable or self-inflating mattress that does not insulate is a guarantee of getting cold.

To know if a mattress has good thermal resistance, look at the R-Value. This standard is common to all mattresses. The higher this number, the more insulating the mattress is. For summer camping, an R-Value of 1 to 2 is generally sufficient (as long as you don't go too high in altitude). But in winter, a mattress with an R-Value greater than 4 becomes mandatory if you don't want to be cold while sleeping. If you plan to sleep in winter at high altitude, an R-Value greater than 6 is required. Note that it is possible to stack two mattresses to add up their R-Values. Thus, if you have a foam mattress and an inflatable mattress, that can work.

Read more : What does the R-Value of a mattress mean?

5. The sleeping bag is imperative

Just as food goes hand in hand with hydration, the mattress goes hand in hand with the sleeping bag. A sleeping bag works as follows: it traps the heat your body gives off. Thus, instead of spreading into the air, the heat stays contained in your sleeping bag.

First, choose a sleeping bag that fits your size. If it's too small, you won't fit entirely and won't be able to close it. If it's too large, the empty space will be useless, and it will take more air to warm you up. To choose the right size sleeping bag, it is recommended to take a bag 25 to 30 cm longer than you. When you put on the hood, it should reach your nose.

Next, once the size is correct, make sure you have a comfort temperature similar to what you will have while camping. This information is indicated on the labels of sleeping bags from major manufacturers (Therm-a-Rest, NEMO, Cumulus...). Don't confuse it with the limit comfort temperature and the extreme temperature, which are less relevant since, for the first, you will still be cold, and for the second, you risk hypothermia and death.

Finally, if you have a down sleeping bag (not synthetic), make sure to unfold it early enough so that it can regain its loft. If it is compressed in your bag all day and you take it out two minutes before sleeping, it will not have time to regain all its properties, and you risk being cold in the first minutes.


6. Use a sleeping bag liner

If after all these tips to sleep without being cold while camping, you are still cold, then you are one of the chilly ones! But that doesn't mean that winter camping is out of reach for you. There are still a few tips, starting with the sleeping bag liner. It is a light sheet that fits inside the sleeping bag. Also known as a sleeping bag liner, it is a compact, lightweight accessory that can add a few precious degrees.

If you want to get one, know that the temperature gain given by the manufacturers is generally a bit exaggerated. For example, the Sea to Summit Thermolite Reactor Compact Plus sleeping bag liner claims an 11°C temperature gain. In reality, you will gain more like 7 to 8°C, which is still very useful in many situations.

7. Don't wear too many layers of clothing

It's a bad reflex that we would all have: piling on clothes. Besides being uncomfortable for sleeping, the risk is sweating. And sweat is the enemy of the camper. It is the best way to create the opposite effect and get cold afterward.

Therefore, it is advisable to sleep with as few layers as possible. Thermal underwear and a merino wool t-shirt will do the trick. Merino is a soft material that limits sweating and regulates temperature. Perfect for sleeping in the trek without getting cold!

Besides, while it is not recommended to pile on clothes, make sure to cover your extremities (head, hands, feet). These are the main entry points for the cold. The hat is therefore mandatory in cold temperatures. The buff can serve as a hat. The sleeping bag hood is also a good option. However, leave your nose and mouth exposed. Otherwise, it can create condensation in your sleeping bag, which will lose its properties.

8. The hot water bottle, a classic

There are several ways to create natural hot water bottles. To do this, you only need to heat water. Then, put it in a water bottle or reuse an empty freeze-dried food bag. You just have to slip it into your sleeping bag, either at your feet or hands. Once the water has cooled down, don't forget to take it out of your sleeping bag.

Otherwise, there are hand warmers. They are easy to use: you light the stick with a lighter. The combustion is slow, allowing you to warm up for many minutes, even several hours for the most elaborate models. We especially think of the CAO Outdoor hand warmer.

9. Exercise before sleeping

Finally, exercising before sleeping is a good way to warm up. We know it's not always easy to motivate yourself after a day of hiking. But it's not about running a marathon. A few push-ups or sit-ups will suffice. The goal is simply to warm up the body.

Doing too much exercise will produce the opposite effect. You risk sweating and making your clothes damp. That is a sure way to get cold!

10. Warm up with a fire

Lighting a campfire warms your hands and, more generally, your body. It can be useful before sleeping while cooking. However, it is not recommended to keep it lit while you sleep, unless you are under the stars and there is no risk of starting a fire (in a snowy area, for example).

For a small side note, prefer a fire in a wood stove rather than a campfire. It helps to preserve the environment. Indeed, a ground fire kills the flora and fauna present underneath. And that's not to mention the ashes once the fire is out or the risk of fire when it is still burning.


This aligns with the Leave No Trace mindset. This educational program teaches people how to reduce their environmental impacts during outdoor activities.

Learn more about the Leave No Trace program, its definition, and its 7 principles

As you can see, there are many ways to stay warm at night while hiking. These tips are well known to outdoor enthusiasts. Remember one thing: it's all about balance. You need to eat well without overeating, exercise a bit without overdoing it, and cover yourself without over-covering to avoid sweating. With time and practice, you will know your body and how to have good nights while camping.