Some people love sleeping bag liners and others aren't so enthusiastic.
But do sleeping bag liners work well enough to spend your hard-earned money on one?
I think you'll be surprised by the results if you enjoy going camping in colder weather for long periods.
Do Sleeping Bag Liners Work?
Sleeping bag liners work by keeping you 5-15+ degrees warmer when you're sleeping in colder temperatures. Liners also keep your sleeping bag clean, protect you from bugs, save you money, and help make laundry day a lot easier.
It's easy to dismiss a sleeping bag liner because it seems more like a luxury than a necessity. I think they're one of the best pieces of equipment to carry with you.
Let's talk about a few reasons why you should always pack one:
- Liners keep you warmer
- Keep your sleeping bag clean
- Extend the life of the sleeping bag
- Protects you from bugs
- Stay clean in sketchy hotels
1 Liners keep you warmer
Do sleeping bag liners really add warmth? A thin liner obviously won't turn your sleeping bag into an oven in winter but they add warmth.
If you're sleeping in freezing conditions it could be the difference between being comfortable or not. Sometimes being a few degrees warmer is amazing.
How much warmth do sleeping bag liners add?
Manufacturers say sleeping bag liners add roughly 5-15 degrees of warmth depending on the material used. I love using a silk sleeping bag liner but it's not the best for heat.
Here are some types of bag liners including how much warmth they give:
Silk sleeping bag liner (5°F)
Silk bag liners are extremely lightweight and don't take up too much room in your backpack. You'll still feel comfortable lying in one when it's warmer outside.
Cotton sleeping bag liner (5°F)
Cotton is a lot stronger and more durable than silk, which also means it's a bit bulkier. It's still a good material especially when you look at the cost.
Fleece sleeping bag liner (10°F)
Fleece bag liners will wick away lots of moisture and don't take very long to dry when you get them wet. The relatively bulky material is also very soft.
Synthetic sleeping bag liner (25°F)
Stretchy CoolMax fabric is a good example of a synthetic sleeping bag liner. It's comfortable and has great moisture-wicking properties that help when it's humid.
Insulated sleeping bag liner (32°F)
Insulated bag liners provide you with lots of warmth although they're pretty expensive. The materials dry a lot faster than others like cotton.
What is the warmest sleeping bag liner?
Insulated sleeping bag liners made from materials like Thermolite are the warmest on the market, but I wouldn't expect the temperature ratings touted by companies to be 100% accurate.
I've found some seem to be a little exaggerated especially when you're camping in winter. Fortunately, they still help keep you warm.
2 Keep your sleeping bag clean
When you've been walking all day you're going to be covered in oils, sweat, dirt, and anything else you've been rolling around it during the day.
You don't want to get into your expensive sleeping bag when you're dirty. But what are you supposed to do when you can't wash before bed?
A sleeping bag liner ensures your sleeping bag stays clean. I love it because it's easy to wash your bag liner during the day.
By the time you go to bed at night, it will be dry. It's like always sleeping in clean sheets, which is wonderful when you're camping for longer than a few nights.
3 Extend the life of the sleeping bag
You can't leave a sleeping bag to stew in its own filth, so when it gets dirty you need to wash it. Even good sleeping bags will only last so many cycles.
Over time a sleeping bag that's been washed too many times will begin to deteriorate. Not good considering how much money you spent on it.
If you sleep in a bag liner you won't get your sleeping bag so dirty it needs to be washed all the time, so it will extend the life of your bag several years.
4 Protects you from bugs
Some sleeping bag liners have a special coating that deters insects. Others still let you avoid insects even if they don't have a special coating.
I like to chill in my sleeping bag liner during the day when it's warm enough. I'll sometimes sleep in one during summer when I don't need my sleeping bag.
When you're inside a bag liner it's going to keep the majority of bugs from annoying you, so you don't need to cover your hammock with a bug net that ruins your view.
If you're going somewhere there are going to be a large number of insects it's not enough, but in most camping locations it's a good bug shield.
5 Stay clean in sketchy hotels
When I go wild camping for long periods I like to book into a cheap hotel now and again to catch up on a few things.
I need to do some work and make sure everything is running smoothly. There are only so many things you can do with a phone that doesn't have much charge left.
Once you start sleeping in sketchy hotels in cheap countries you realize you don't want to touch the sheets when you go to bed. Who knows what's been in contact with them.
So I use my sleeping bag liner to keep my body away from bed sheets that probably haven't been washed thoroughly in years. I know I won't be pregnant when I wake up.
Choosing The Best Sleeping Bag Liner
If you want the best sleeping bag liner you have to choose one based on your specific needs. The material you choose is the biggest decision you need to make.
Here are a few more features you should keep an eye on when choosing a bag liner:
- Water repellant
- Foot box design
- Drawcord hood
- Insect repellant
- Full-length zippers
The Sea to Summit Thermolite Reactor series are probably the best sleeping bag liners if you care about extra warmth more than anything else although they do have extra features.
Which is better silk or cotton sleeping bag liner?
If you don't care about warmth but you'd like all the other qualities a sleeping bag liner provides I think silk and cotton sleeping bag liners are the best choice.
Not only do that squeeze into a stuff sack so small you can hide them away in your backpack, but they're also really comfortable. Cotton is great because it's so cheap.
Is a silk sleeping bag liner worth it?
Should you pay the extra money to get silk when you can use a cotton bag liner? I think it depends on whether or not you have extra cash lying around.
Cotton is fine if you don't want to spend lots of money, but silk is much more breathable and wicks away moisture. Two important qualities you want when it's warmer.
And who doesn't want to sleep in silk? You'll feel like a prince when you're lying in your hammock.
Who makes the best sleeping bag liners?
Sea to Summit makes the best sleeping bag liners at the moment. We've talked about the Reactor liners but they have other great ones like CoolMax liners too.
There are premium silk models or you can choose a silk/cotton blend. Whether you're camping in winter or summer you'll find what you need.
Cocoon and Western Mountaineering are also good sleeping bag liner brands.
Can you sleep in a sleeping bag liner in summer?
In summer you need a hammock sleeping pad or underquilt because it still gets cold at night and you need bottom insulation. It's one of the best ways to stay warm in a hammock at night.
But when it's warm you can sleep in a sleeping bag liner instead of your sleeping bag as long as you have bottom insulation. Will you be able to do it every night?
If you have a sleeping bag with you it doesn't matter. Once you feel it's getting a little cold you can jump into the sleeping bag. Until then the bag liner is good enough.
You'll spend a lot of time in your bag liner without your sleeping bag.
How can I increase the warmth of my sleeping bag without a liner?
The best way to increase the warmth of your sleeping bag is to use a bag liner, but how do you stay warm when you don't have one? There are only a couple of other options:
- Hammock top quilt
- Extra layers of clothes
Hammock top quilt
A top quilt is almost the same as a sleeping bag except it's more like a blanket than a bag. They can be made from the same materials.
Top quilts have a foot box at the bottom so you won't have to worry about it falling off in the middle of the night. You can still use top quilts when sleeping in a tent too.
Unless it's pretty cold outside a top quilt is a bit too much. Sleeping bag liners are more than adequate.
Extra layers of clothes
You can also wear an extra layer of clothing if you want an easy way to stay warm in your sleeping bag. How many layers do you wear to bed at the moment?
When it's expected to get chilly outside it's good to have thermal underwear tucked away in your backpack. It never hurts to have a hat, scarf, and gloves too.
If you want to turn up the temperature when you get into bed you could use a hot water bottle.
How to make a DIY sleeping bag liner?
Do you know how to use a sewing machine? If you don't know how to operate one maybe you know someone who does. It won't take long to make a sleeping bag liner.
All you need is the fabric you're going to use and your sleeping bag to create an outline. Your DIY bag liner should be the same size as your sleeping bag.
Unless you want to get fancy just trace the shape of your sleeping bag (minus the hood) onto your fabric two times, cut out the shapes using scissors, and sew them together.
The most important part is choosing the right fabric:
Hot and humid conditions – lightweight moisture-wicking fabric
Cold winter conditions – heavier insulating fabric
Should You Use A Sleeping Bag Liner?
A sleeping bag liner does keep you 5-15 degrees warmer on cold nights so it's worth taking one camping. You will only have to wash your bag liner instead of your sleeping bag. It's also great chilling in a sleeping bag liner during the day.
There are so many positives it seems crazy not to use a sleeping bag liner. If you can't afford one you can use a DIY sleeping bag liner so money isn't an issue.
The only downside is the fact it will take up some space in your backpack. Just take a silk or cotton sleeping bag liner if you're packing light.