Sleeping Bag Clothes Explained: What To Wear In A Sleeping Bag

What To Wear in a sleeping bag

Camping in the cold can be downright miserable if you’re not prepared. Nothing ruins a camping trip faster than failing to prepare for cold weather. Obviously you need the usual cold weather sleeping gear: sleeping bag, sleeping pad, and sleeping bag liner, but what about clothes? Do you need to wear lots of layers to stay warm at night or can you strip down. What should you wear in a sleeping bag?

It’s always warmer to wear clean comfortable clothing in your sleeping bag. Every layer of clothing you wear adds insulation between your body and the cold outside air! In warmer weather you can get by with gym shorts (or underwear) and a T-Shirt in your sleeping bag, but you’ll need additional insulation layers on chilly nights. I recommend wearing pajamas or sweatpants, merino wool socks, winter hat, and a light sweater in cold weather.

Campers can’t seem to make up their minds on whether or not they should wear layers in their sleeping bag. Some people like to sleep naked in their sleeping bag or wear underwear and there’s another extreme that throws on jackets, base layers and pants in a hope to boost warmth.

I fall into the buy a bag with the right temperature rating camp and wear a light base layer in your sleeping bag camp. Wearing a warm base layer will make you warmer, but choosing the right sleeping bag and pad for the nighttime temperatures is 99% of the battle. At that point you can further regulate your sleeping bag’s temperature by unzipping the bag a little bit. You shouldn’t be relying solely on clothing to keep you warm at night.

In the rest of this post I’ll explain what you should wear in your sleeping bag, go over clothing layering systems, and give a few tips for increasing your sleeping bags temperature rating. You shouldn’t have any trouble deciding what to wear in a sleeping bag by the end of this post.

Should You Wear Clothes In A Sleeping Bag?

Let’s start off with a simple question with a not so simple answer. Should you wear clothes in a sleeping bag? A lot of people think you don’t need to wear clothes in a sleeping bag if you’ve picked the right sleep system.

They actually believe that sleeping naked in a sleeping bag will increase warmth, but that’s an old wives tale. There are a few cases where that may be true, like if your clothes are wet, they cut off circulation, or you’re compressing the sleeping bag’s filling, but 99% of the time it will be warmer to wear clothes to bed.

Wearing clothes to bed adds another layer of insulation to trap body heat. Layering clothing will increase the temperature rating of your sleeping bag making an underrated bag perform below its temperature rating.

Plus wearing clothes will reduce the dirt and sweat that gets into your sleeping bag delaying wash cycles. Every time you wash your sleeping bag the down/synthetic fill contracts making it less effective. Using a sleeping bag liner is another way to protect your bag and increase the amount of time between wash cycles.

What Should You Wear In a Sleeping Bag?

There’s no overall consensus when it comes to figuring out what you should wear in a sleeping bag. It’s one of those controversial topics that people have been arguing over for decades. The main disagreement is over how much you should wear in your sleeping bag.

Like everything in life the camps are split into two extremes. One side thinks that you should always layer up with base layers, jackets, pants, and socks to increase insulation. The other side argues that you’ll be warmer if you sleep in as little clothing as possible. They think it’s ridiculous to wear lots of layers if you choose a quality sleep system designed for the expected nighttime temperatures.

Both sides have a strong case, but it really depends on what time of year you’re camping and how much gear you own. If you can afford to buy a thick high R-Value sleeping pad and multiple sleeping bags to match the weather conditions go ahead and strip down. The rest of us will layer up to get the most out of our sleeping bags.

You will always be warmer if you wear clothing in your sleeping bag. It’s simple physics! Your body works like a low energy furnace and you need to find a way to keep the heat from escaping the bag. That either means buying a sleeping bag with lots of insulation rated 15°F lower than expected nighttime temperatures or wearing additional layers to make up for an inadequate sleeping bag.

I don’t have the money to buy multiple sleeping bags rated for the heat of summer, cool spring/fall nights, and extreme winter temps. So I find other ways to pad my sleeping bags temperature rating. That means dressing in base layers and using a sleeping bag liner to extend my sleeping bags temperature rating.

That means wearing some type of base layer in warmer weather and multiple layers in the cold. Here’s what you should wear in a sleeping bag to stay warm.

  • Base Layer Shirt: I normally go shirtless in the summer, T-Shirt in the spring/fall, and wear a merino wool thermal shirt on colder nights. Merino Tech Merino Wool Baselayers are affordable thermal shirts and they’re extremely comfortable. Smartwool shirts are a little bit warmer, but almost twice the price!
  • Comfortable Pants or Shorts: Wear lightweight gym shorts in warm weather and long johns, pajama pants, or sweatpants in cold weather. I like to wear my merino wool long johns under a pair of sweat pants on chilly nights. You may even want to wear lightweight snow pants over your base layer in the winter.
  • Merino Wool Socks: Sleeping bags provide consistent insulation throughout the bag, but most of your body heat is released through your torso. That means the center of your bag will be warm and it will get colder as you go farther down the bag. Wearing a pair of merino wool socks to bed will keep your feet warm evening out the temperature extremes in your bag.
  • Light Jacket or Sweater (Cold Weather): You may want to put on a light jacket or sweater to keep your chest warm in cold weather. This isn’t necessary with a sleeping bag that’s rated for extreme temps, but it will really help if nighttime temps are nearing your bags rating. I carry a lightweight fleece jacket to wear at night, but a down puffer jacket (like this one) will keep you warmer at a similar trail weight. Feel free to layer up multiple jackets, but try not to contract the outside baffles on your sleeping bag.
  • Winter Hat (Cold Weather): Your head won’t be protected in a sleeping bag so it’s important to wear a winter stocking cap on cold winter nights. Sleeping bag hoods provide some warmth while blocking the wind, but you should really consider wearing winter hat to bed in the cold.
  • Mittens Optional (Cold Weather): There’s less blood circulating through your hands and feet so they’ll get colder than the rest of your body. I have a hard time sleeping in mittens, but a lot of cold weather campers wear them to bed. They’ll definitely help keep your hands warm so it’s worth considering.

It’s hard to give you a set recommendation on clothing to wear without knowing the night time temperatures and the sleep system you’re using. Buying a high R-Value sleeping pad and Sleeping bag with the right temperature rating for the conditions will keep you warm in 99% of situations.

If that doesn’t work you can always pad your sleeping bags temperature rating with a sleeping bag liner. Sleeping bag liners also help protect your bag from sweat/dirt and increase the time between wash cycles so I always use one. I use the Sea To Summit Reactor Liner, but it’s pretty expensive. It adds 25°F to your bags temperature rating and I use it without a bag in the summer down to 50°F nights.

The Coleman Sleeping Bag Liner is a much cheaper option that adds 12°F to your bags temperature rating. It’s rated down to 50°F, but you’ll be chilly if the temperature dips below 60°F without a sleeping bag. You really can’t beat it for the price though!

Before I explain how to layer clothes in a sleeping bag let’s quickly go over sleeping pad R-Values and sleeping bag temperature ratings. You’ll be miserable regardless of what you wear without the right sleep system for the weather.

Should You Wear Socks In A Sleeping Bag?

Sleeping Pad R-Values and Sleeping Bag Temperature Ratings Explained

The clothing you wear in your sleeping bag will help keep you warm, but you won’t be comfortable with a poorly chosen sleeping bag/pad. When it comes to warmth, there are two main factors you need to consider when choosing a sleep system. You have to consider the sleeping bags temperature rating and sleeping pads R-Value.

It doesn’t matter what type of bag/pad you choose! If you figure out those two things you should be comfortable sleeping at night. Here’s a brief overview of temperature ratings and R-Values.

  • Sleeping Bag Temperature Rating: Sleeping bag temperature ratings don’t tell you the temperature rating that you’ll be comfortable at! It’s actually the temperature rating where you may start to experience safety issues. So you’ll be freezing if the temperature dips close to the bags advertised temperature rating. I recommend buying a sleeping bag that’s at least 15°F colder than expected nighttime temperatures. You can further pad the rating with a sleeping bag liner and lots of layers.
  • Sleeping Pad R-Value: Sleeping pads protect your body from heat loss through the cold ground. As you go into higher R-Values the pad will be warmer. It doesn’t matter what type of sleeping pad you use as long as the R-Values suitable for the weather conditions. You can stack foam and inflatable/self-inflating pads to increase R-Value in cold weather. Look at the R-Value chart above to figure out a bag for your needs.

Sleeping Bag Liners Will Increase Your Bags Temperature Rating

Once you have a sleeping bag and pad picked out you should seriously consider picking up a sleeping bag liner. A sleeping bag liners main job is to protect your bag from sweat, dirt, body oils, salt, and anything else that’s on your body, but it will also pad the temperature rating.

How much the liner adds to the temperature rating will depend on the liner you choose. Sea to Summit is the king of sleeping bag liners, but they can be expensive. I highly recommend their liners, but go with a cheap Coleman liner if you’re on a tight budget. It’s affordable, extremely durable, and adds 12°F. The only downside is that it’s heavy at 1lb 10oz.

There are two Sea to Summit liners that 99% of people choose between. The Sea To Summit Reactor Liner adds 25°F to your bags temperature rating, and the Reactor Fleece Insulated Liner adds 32°F to the bags rating. The reactor liners is a little bit lighter and comes in different lengths so go with that one if you use an oversized sleeping bag.

How to Layer Clothes in a Sleeping Bag

Layering clothes in a sleeping bag will really help increase the insulation in your bag. Every additional layer between your body and the outside air adds insulation to your bag improving the comfortable temperature rating. I recommend always wearing something in your sleeping bag. You can always strip off clothing or unzip the bag to let in a breeze if you get hot.

Unfortunately, most of us can’t afford to buy gear designed for only one season. A bag that’s comfortable in the summer, will be chilly in spring/fall, and freezing in the winter. I don’t recommend using a summer bag in the winter, but you can increase your bags temperature rating with a high quality liner and layering clothing.

A 40°F sleeping bag seems to be the sweet spot for most people. It’s comfortable in the summer and provides enough insulation for chilly spring/fall nights. When you pair it with a reactor sleeping bag liner and warm clothes it can be used in 25°F weather. You would want a warmer sleeping bag for winter use, but a 40°F bag is perfect for 3-season use.

So lets get into layering clothing to increase warmth. Layering allows you to use 3-Season gear for a wide variety of applications. Most experts break down clothing into 3 distinct layers: base layer(underwear layer), middle layer (insulating layer), and outer layer (shell layer).

  • Base Layer: In the summer, your base layer will usually be underwear, gym shorts, and a t-shirt. Your sleeping bag provides plenty of insulation so you don’t need to wear a middle insulating layer or outer layer. On cold nights you’ll want to wear long johns, pajama pants, or sweatpants and long sleeve shirt like a merino wool base layer. I usually merino wool long johns (these ones), sweatpants, merino wool socks (Smartwool Socks), and a long sleeve merino wool shirt (my favorite).
  • Middle Layer(insulation): The middle layer is used as the insulating layer. Most people wear either a fleece jacket or light down/synthetic jacket and a winter hat. I like to wear a hood, but that’s uncomfortable for some people. If you’re insulating layer is comfortable to wear on its own during the daytime temperatures it should be perfect at night. You can also wear snow pants if your legs get cold easily.
  • Outer Layer (Shell Layer): I highly doubt you’ll need to wear an outdoor shell layer in a sleeping bag. It won’t hurt on extremely cold nights, but the outer layer is mostly for wind/water protection. Your tent and sleeping bag provide enough protection from the outside weather so you should be fine without a shell layer.

Spring and Fall Weather is Unpredictable

Remember that spring and fall weather can be unpredictable. It can be 60°F on your first night and drop into the 30s the rest of the trip. You may even run into 40°F temperature swing between day and night temperatures. Try to look at the weather forecast, but plan on extreme temperature swings.

Bring extra clothes and a sleeping bag liner to add versatility to your sleep system. Wear extra layers on cold nights, use your sleeping bag liner, and bags zipper to adjust the temperature of your gear. You should be able to handle anything with lots insulation of layers to choose from.

It’s Always Easier to Remove Layers

Every additional layer adds more insulation between you and the cold outside air. Try to keep heat close to your body and regulate temperature by zipping and unzipping your bag. Start off the night with lots of layers and slowly ditch them as you overheat during the night.

Throughout the night the temperature will probably swing 10-20 degrees. If zipping and unzipping your bag isn’t enough you can always take off and put on additional layers in the middle of the night. I usually keep a light jacket stuffed in my sleeping bag so I can quickly toss it on if I get cold. Keeping it in your bag will keep the jacket warm so you won’t get a temperature shock like you’d get from a jacket stored in your pack.

Can I Sleep Naked In Sleeping Bag?

There are lots of campers that choose to sleep in the nude, but I’m not a fan. I feel exposed when I’ve tried sleeping naked in the past. Thin fabric tent walls don’t offer much protection from the outside and you can’t get up to pee during the night and scare off animals that are going after your food.

I can see the draw of sleeping naked when you’re camping in remote areas. Sleeping bags are designed to keep you warm so why wear extra layers? This line of thinking works really well in the summer, but it gets complicated in cold weather. If you decide to go this route, your best bet is to pair your bag with a liner so you have more flexibility.

You might want to check out my post about sleeping naked in a sleeping bag for more info.