Sleeping Bag Liners - all you need to know

My sleeping bag liner!

1. What are they
   A sleeping bag liner is a lightweight, removable layer that sits inside your sleeping bag, acting as a barrier between you and the bag itself. They are typically made from materials such as cotton, silk, fleece, or synthetic blends, and come in different shapes to match the style of your sleeping bag. Liners can be rectangular, mummy-shaped, or designed to be used on their own in warmer weather.

   Liners come generally in two forms:

   Whole body liner: Usually made from silk, cotton, or lightweight synthetics, these are designed primarily for hygiene, moisture control, and a modest boost in warmth. They are light, compact, and quick-drying, making them ideal for summer camping, backpacking, or travel where space is at a premium.

   Fleece liner: Constructed from soft, insulating fleece fabric, these are bulkier but much warmer. They can add significant insulation to your sleeping bag in cold conditions and may even be used on their own in mild temperatures. However, they are often slightly heavier to carry and take up more pack space, so they are better suited to winter camping or situations where weight is less of a concern.

2. Why use them
   Liners add a layer of warmth in cooler conditions and can help regulate body temperature in warmer climates by removing moisture. They also keep your sleeping bag cleaner for longer, reducing the need for frequent washing and helping to preserve the insulation and overall lifespan of the bag. This is particularly useful for down sleeping bags where washing isn’t the easiest!

   Often, when hiking to huts, they will require some sort of liner to sleep in. This was the case when I did the GR20 in Corsica in 2023.

3. Advantages
   Using a liner can improve comfort by offering a softer feel against the skin compared to the sleeping bag’s inner fabric. They are versatile, providing extra warmth in cold weather, serving as a standalone sleeping option in hot weather, and offering a hygienic layer when using hostel beds or huts. Liners are also compact and easy to pack, making them a convenient addition to any hiking or camping kit.

4. What to be careful of
   Not all liners are suitable for all conditions. Some materials, like fleece, can be too warm for summer camping, while silk or thin synthetic liners may not add enough warmth in cold weather.

   Poor-quality stitching or ill-fitting designs can cause discomfort during the night. It’s also worth noting that a liner will not replace the need for a suitable sleeping bag in colder environments.

5. How to wash
   Always check the manufacturer’s instructions before washing. Most fabric liners can be machine washed on a gentle cycle using a mild detergent (or to be on the safe side, no detergent/softener), though silk and certain technical materials may require hand washing with a specialised cleaner.

   Avoid using fabric softeners, as they can affect moisture-wicking properties. Allow the liner to air dry fully before packing away to prevent mildew and odour build-up.

6. My sleeping bag liner recommendations:

   • SeatoSummit Reactor Liner (the one I use!)

     Thermal boost +12%

     Weight: 348g

     Price: £60 (2025)

   • Nemo Tracer

     100% recycled materials

     Weight: 258g

   • Cocoon Mountain Wanderer

     Thick liner, adding up to 12degC

     Weight: 547g