Do You Need a Pad Under a Sleeping Bag?

If you sleep in a cold environment, do not even think of sleeping without a sleeping pad or anything similar that can protect you from the cold ground.

You need a sleeping pad under your sleeping bag for two major reasons:

  • Protection from the cold.
  • Comfort.

Both reasons hold if you sleep outdoors. For indoor sleeping this is mainly about comfort.

Do You Need a Pad Under a Sleeping Bag - top picture showing a camper inflating a pad.

Protection from the cold

When you sleep in a sleeping bag, the part which is under your body is compressed. So its insulation is mostly without air, and this means it loses its insulating property. If you have seen sleeping bags without bottom insulation, now you know why this is so.

This is why you need a sleeping pad that adds this critical insulation from the ground. In fact, this ground insulation is far more important than the insulation from the surrounding air.

Here are a few facts that may surprise you:

  • In average, you can expect to lose around 40 times more body heat to the soil than to the air. This depends on the type of ground.
  • If you sleep on a rock, you will lose around 55 times more heat to the ground than to the air.

What is R-value?

For the reasons mentioned above it is important to have a sleeping pad with an appropriate R-value. This is a parameter that describes thermal resistance of the material used for the sleeping pad construction. The Therm-a-Rest NeoAir Xlite pad shown in the top picture above is ultralight but it has 4.2 R-value, so it is good for all seasons.

More about this you can see in this video from the brand that is one of the best known in this field, please have a look:

How high R-value do you really need? This will depend on a number of factors. The simplest inflatable sleeping pads are only with air inside and they normally do not have R-value indicated. My guess is this is in the range 0.5-0.8, and you can use them for summer camping only.

For cold weather, you should have R-value at least 4, the higher the better. But the higher R-value implies more weight, so if this is about trail use, you will have to find a proper balance.

Note that from 2020, some top brands have adopted ASTM F3340-18 sleeping pads rating, and it is best to go for a pad that indicates that its R-value is according to this standard. But the most important final test is when you check how the pad works for you.

Comfort

A sleeping pad provides cushion and this makes a lot of difference. Trail sleeping pads may be thin but this is enough in particular if you are a back sleeper.

Inflatable sleeping pads may be very thick but they are less comfortable than self-inflating sleeping pads or foam pads. But there are some innovative designs that include both.

So in such a pad, one part is self-inflating and one part is inflatable, this is the case in the KLYMIT KLYMALOFT Sleeping Pad shown in the picture. The reason for such a hybrid construction is that you have more support in the areas where this is more needed.

KLYMIT KLYMALOFT Sleeping Pad.
KLYMIT KLYMALOFT Sleeping Pad.

How do you keep a pad under a sleeping bag?

  • Some sleeping bags have a sleeve for a pad, and this is a really useful feature. But the fact is that this mostly with the bags that are without bottom insulation. You can see this in Big Agnes Lost Dog sleeping bags series.
Big Agnes Lost Dog sleeping bag bottom with a pad in place.
Big Agnes Lost Dog sleeping bag bottom with a pad in place.
  • Some top brands like Sea to Summit make their sleeping pads with silicone grip patches. Sometimes this is mainly to keep a pillow in place, but it may help a bit with the bag as well. But in some models they have a non-slip grip print all over the pad, you can see this in their Sea to Summit Ultralight Self-Inflating Foam Sleeping Pad.
  • A slightly deflated pad will usually be more stable, so use this if you move a lot during the sleep.
  • In general, if you have a wide, bulky, and heavy sleeping pad, it will stay firm underneath you.

How about putting a sleeping pad in a sleeping bag?

So instead under this is now about in the bag. This is not a common practice and one obvious reason is the fact that many sleeping bags are narrow so there is no space to put a pad inside.

But there may be circumstances when you would put a pad in the bag if this is physically possible. These include:

  • If you turn around a lot, you may end up sleeping without the pad under you. But as mentioned above, some bottomless sleeping bags come with a sleeve where you put the pad and it will remain in place.
  • This can be also in situations when you have a thin inflatable pad and you have to use it on a ground that has sharp objects. Placing it in the bag may reduce chances for puncture. But you may end up with a damaged sleeping bag instead.
  • I have seen some who sleep in hammock saying that it may be better to place the pad in the bag. But instead of doing this, I want to stress that there are sleeping pads designed for hammocks, this Klymit Hammock V sleeping pad is one example.
 KLYMIT Hammock V Sleeping Pad.
KLYMIT Hammock V Sleeping Pad.

What to use instead of a sleeping pad?

So this is about improvising if you do not have a pad. There are many options, just use your imagination. Whatever adds to comfort and separates you from the ground will help. I shall mention just a few options.

Use a cot

You may separate yourself from the ground if you sleep on a cot. In this case, you might need far less insulation, or you may sleep without a sleeping pad if this is about 3-season camping.

It is important to be off the ground. You can use a cot also in combination with some other options mentioned below in the text.

Can you use a yoga mat as a camping mat?

I have seen this question being asked. So the answer is yes, this can help a bit but not for a very cold environment. Besides, such mats are thin and they do not provide enough cushion for a comfortable sleep.

Using cardboard instead of a sleeping pad

If you have a few pieces if a corrugated cardboard, it will do the job nicely in particular against cold. You can add as many layers as you have, the more the better.

Moss and dry leaves

If this is what you use, make sure it is not wet or you will make the situation even worse. Dry leaves tend to move underneath you, so make sure you put a lot of it, and try to stabilize it somehow.

You can also use dry ferns or any other leafy plant or simply grass. If it is green and you have time, cut it down and let it dry during the day.

Blanket(s)

This brings some memories from the distant past. My wife and me used two blankets in a tent on our honeymoon. One was underneath us instead a pad. It worked.

Final thoughts

In summary, the answer to the question in the title of this post is yes, you need a sleeping pad when you sleep outdoors. This is both for cold and for comfort. But if this is about summer camping, you can manage without it. This may be so even in a cold climate, just use your imagination.

You might want to bookmark this site and visit it occasionally, you will always find new texts added. For more similar stuff check in the category Camping. Check also my another text where the question is answered if a sleeping pad can be too warm.

Thank you for reading. Let me know if you have questions, there is a comment box below. Have a nice day.

 
Me on Jalovec.Hi, I am Jovo, the founder of this OutdoorsFAQs site and several other outdoor sites. I have been mountaineering for almost 40 years already, and I have created this site to use as a reference for various questions that I receive in my sites. Being a theoretical physicist by profession, I tend to base my answers on facts and on my own personal experience.

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