Big Agnes Women’s Sidewinder SL 35° review: an innovative sleeping bag for sideways snoozing

The Big Agnes Women’s Sidewinder SL 35° is the perfect sleeping bag for those who like to curl up and sleep on their sides

Big Agnes Women’s Sidewinder SL 35°
(Image: © Big Agnes)

Advnture Verdict

An innovative alfresco sleeping solution for side sleepers, which remains comfortable whichever way you like to lie.


  • +

    Great for side sleepers


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    Mesh pillow holder lets in cold air if you’re not using a pillow

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Big Agnes Women’s Sidewinder SL 35°: first impressions

Side sleepers, say hello to the Big Agnes Women’s Sidewinder SL 35°, the sleeping bag of your dreams (if you’ve managed to have any). A common bugbear for campers is that most sleeping bags and sleeping pads do not allow people to enjoy a good night’s sleep unless they like to lie flat on their backs or fronts (see: Types of sleeping bag). Side sleepers endure all sorts of discomfort, because of the design of their bags and slimness of their mats. However, the patent-pending Sidewinder Series sets out to eliminate potential side sleeping pressure points with its innovative design, which made it a shoo-in for our Best women’s sleeping bags buying guide. Salvation for side sleepers at last!

The female-specific version of the bag also keeps you warmer and more comfortable by following feminine contours with a more gradual shoulders-to-feet taper and body-mapped insulation. The jacket-style hood also traps warmth inside.

This bag's down fill and interior and exterior shell fabric are both treated with a PFC-free water repellent finish to keep the bag from compacting from sweat and other moisture. Maybe we should add this bag to our Camp in comfort: 15 tips to get a good night's sleep feature.


RRP: Petite $250 (US) / £285 (UK) Regular $270 (US) / £285 (UK)
Weight: Petite 936g / 2lb 1oz Regular 992g / 2lb 3oz
Max user height: Petite 165 cm / 5ft 5in Regular 178cm / 5ft 10in
Packsize: 20 x 45cm / 8 x 17.5in
Fill: 650 fill water-repellent DownTek with Bluesign-Certified PFOA and PFOS free DWR
Comfort: 1.5°C / 35°F
Limit: Not listed
Compatibility: 2- to 3-season camping at sea level or in the low hills

In the field

With the Sidewinder SL, Big Agnes got creative to make side sleepers more comfortable, with little details like 100% post-consumer recycled synthetic insulation in addition to down in the hips and feet to help alleviate pressure points when you sleep on your side, not your back or stomach. But one of the best things about this bag for me was the fact that it was comfortable whether I slept on my side or my stomach or back.

The anti-snag locking zipper – which runs down the center of the bag, not the side – didn’t work its way open during the night, which often happens to me with other bags. And a double draft tube kept out the breeze.

When I was pushing the limits of this bag’s comfort rating, I kept the cold out by cinching the hood cord, which drew the down-insulated tube on the upper hood opening to my face. When I had the bag fully cinched down, the mesh pillow cutouts kept the bag from feeling claustrophobic.

The Sidewinder comes with a storage bag and a compression sack. And when I wasn’t using the bag, or I needed to air it out, hang loops at the foot hooked over a hanger or branch. A small internal pocket holds a headlamp or a car key.

Berne Broudy

Vermont-based writer, photographer and adventurer, Berne reports on hiking, biking, skiing, overlanding, travel, climbing and kayaking for category-leading publications in the U.S., Europe and beyond. In the field, she’s been asked to deliver a herd of llamas to a Bolivian mountaintop corral, had first fat-biking descents in Alaska, helped establish East Greenland’s first sport climbing and biked the length of Jordan. She’s worked to help brands clean up their materials and manufacturing, and has had guns pulled on her in at least three continents.