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Adventure Tips

Which sleeping bag liner should I choose?

Which sleeping bag liner should I choose?

There are many really good reasons for using a liner as part of your Sleep System. Here's a guide explaining what a liner can do for you, how to choose the right one, and how to care for it. 

    When you are assembling a Sleep System, the liner forms the next-to-skin layer. It can increase your comfort, add some warmth in cooler temperatures and wick moisture from your skin in warmer, more humid conditions.

    Once you have used a liner as part of a Sleep System, you will quickly become used to how much better you sleep. The overwhelming majority of people who choose a liner never go back to sleeping without one.

    Many of those outdoor users first try a liner not because they are expecting a change in their sleeping climate, but for the same reasons that someone at home would put sheets on a bed: You don’t sleep directly on a mattress or quilt, because they are harder to clean than a set of sheets.

    Out in the wild, this factor increases by maybe tenfold as you bring a day’s worth (maybe even week’s worth…) of sweat and trail griminess into your sleeping bag. A sleeping liner prevents this grime from contaminating the liner, and shell and insulation of your bag - and it’s much easier to clean a liner than it is to wash a down sleeping bag or synthetic sleeping bag.

    protect your insulation (and protect your investment)

    The build-up of oils from your skin can migrate into the down or synthetic fill of your sleeping bag—preventing it from fully lofting and keeping you warm. Why pay for a high-quality sleeping bag only to reduce its performance?

    The fine-grain sand that your feet may bring into a sleeping bag can also work its way through the inner fabric. Once these small grains make their way into the insulation, they can act like sandpaper and damage the down or synthetic fill.

    Using a liner significantly reduces the frequency with which you will need to wash your sleeping bag and will extend its life. Along with correct storage, it is the single simplest thing you can do to protect the investment you made in a sleeping bag. And – not needing to replace an item is the greatest contribution towards sustainability that you can make.


    In addition to prolonging the life of your sleeping bag over years to come, a liner made of a functional, technical fabric can improve your sleep comfort night after night.

    A Reactor series liner will add warmth to your sleep environment by trapping extra insulating air in its hollow-core fibers and in infra red-absorbing pigments within the fabric. It also wicks moisture effectively, helping to keep you drier and thus less likely to be subject to evaporative cooling.

    A Breeze series liner wicks moisture even more effectively, thanks to its Coolmax fibers. The wicking process reduces the clammy feeling you may get in warm, humid conditions, especially if your sleeping bag does not have the soft, breathable lining fabrics and ventilating zippers that are the hallmarks of most Sea to Summit sleeping bags.

    Even gram counters will use a liner, especially on a thru-hike – the increase in comfort and the reduction in dirt migrating into their sleeping bags are considered to be well worth the small amount of extra weight they are carrying. Their first choice would be the Silk Blend liner (which has Comfort Stretch Panels built into the side seams)

    use in hostels, huts or couch surfing

    Travel with a liner, and you always have hygienic sheets, wherever you go. Protect yourself from dodgy looking hostel bunk beds, questionable hotel beds or generously offered (but nonetheless slightly grubby) couches. In summer, a sleeping bag liner can even be used as a standalone sleeping bag.

    choosing the right sleeping liner

    weight and packed size

    If packed volume and weight are your most important criteria, you may well choose the Silk Blend Liner. The Compact Mummy version (suitable for sleepers up to 5’10” / 178cm) weighs a mere  4.6 oz / 130g.

    If your weight budget includes a few more grams, and you would like to boost the thermal performance of your Sleep System, your liner of choice may well be the Reactor or Reactor Extreme. The Compact Mummy Reactor with base drawcord weighs 9.5 oz/ 268g.

    If weight is not a significant criterion for you, the Comfort Blend Liner is an excellent, budget-friendly moisture-management choice.

    fit and construction

    Reactor, Breeze and Silk Blend liners come in a Compact Mummy or Mummy shape. Breeze, Silk Blend and Comfort Blend liners are offered in a Rectangular with Pillow Sleeve (and the Comfort Blend is available in a Rectangular shape).

    Your liner does not have to exactly match the shape of your sleeping bag - the stretch-knit fabrics (Reactor, Breeze and Comfort Blend liners) move freely with you so you will never feel constricted. Our Silk Blend Liners also have Comfort Stretch Panels to provide a unique level of comfort.

    how to wash your sleeping bag liner

    Easily. All our sleeping liners are machine washable and require only standard laundry detergent. If you’re using a top-loader washing machine, place the liner in a pillowcase or laundry bag first to stop any drawcords being caught up in the impeller.

    Steer clear of fabric softeners when cleaning your liner as they can affect the wicking properties of the material.

    To dry your liner, it’s best to hang it on a washing line to air dry. Using a dryer could expose a Silk Blend Liner to excessive heat, which can damage the fabric.

    which liner is best for me?

    All of our liners feature HeIQ Fresh, a biocide-free amino sugar treatment that effectively neutralizes odors, keeping the liner fresher.

    Adding warmth to your sleeping bag with the reactor series

    If your sleeping bag needs a thermal boost for a particular trip, check out our Reactor Series. You can even use a Reactor as a stand-alone summer ‘sleeping bag’. The stretch-knit fabric is incredibly comfortable, allow generous freedom of movement and wicks moisture well. Bonus – the Reactor, Reactor Extreme and Reactor Fleece are all available with a footbox drawcord which aids ventilation and allows you to ‘hitch up’ the liner and walk around camp (great for middle of the night bathroom breaks)


    Silk Blend Liners wick moisture and are quick to dry. The Mummy shape is suited for backpacking and the Rectangular with Pillow Sleeve is a great addition to hostel living. Important point for those who may have previously found woven-fabric liners to be constrictive: the side seams have polyester/Lycra Comfort Stretch panels that give you greater freedom of movement.


    Coolmax Breeze liners wick moisture and dry quickly. They’re also really stretchy—so if you’ve ever felt constricted in a liner, this is the answer. Available in both a Mummy shape and a Rectangular with Pillow Sleeve version, the Breeze liner is the foundation of your warmer-weather Sleep System or your go-to travel option for more humid climates. The Mummy version has a footbox drawcord for greater ventilation. It allows you to ‘hitch up’ the liner and walk around camp (great for middle of the night bathroom breaks)


    If packed volume and weight are less of a concern, the Comfort Blend liner is a luxurious addition to your sleep system or travel gear. The knitted construction offers a significant degree of stretch without side seams to interfere with your sleep comfort.



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