Big Agnes Sidewinder 35°F Women’s Sleeping Bag – 650 DownTek, Regular (Lyons Blue/Teal)

Meet the Big Agnes Sidewinder (650 DownTek) Sleeping Bag, a warmth-focused option designed for those who naturally sleep on their sides. Its ergonomic shape and body-mapped insulation work together to keep you cozy as you shift from one side to the other, night after night. The bag blends a lofty DownTek fill with targeted synthetic insulation where it matters most, delivering comfort without compromising mobility.

Designed for side sleepers

The Sidewinder SL is purpose-built to move with you through the night. The combination of body-mapped insulation and a thoughtful cut helps minimize pressure points while maintaining warmth in key zones.

• Body-mapped insulation targets warmth where you need it most.
• Synthetic insulation in the hips and feet cushions pressure points for restful sleep.
• Ergonomic shape and a contoured fit align with side-sleeping positions.

Warmth, fit, and control

The thermally efficient footprint and a close-fitting, jacket-style hood keep insulation close to the body without restricting movement. An insulated tube along the upper hood opening seals out drafts for added warmth when you’re sleeping under cool night air.

• Optimized fit for side sleeping reduces drafts and enhances warmth.
• Jacket-style hood provides mobility while keeping warmth close to the head.
• Long, ambidextrous zipper offers easy entry and exit from either side.

Practical design details

In addition to warmth, the Sidewinder includes thoughtful features to simplify camp life.

• Pillow Barn keeps your pillow in place with easy interior access for adjustments.
• Anti-snag locking zipper with a draft-free garage ensures smooth operation.
• Exterior loops make hang drying and storage straightforward.

Materials, care, and sizing

The primary fill is 650-fill DownTek, which resists moisture while preserving loft. Bluesign Certified water-repellent chemistry avoids PFOS/PFOA while maintaining performance. The body-mapped synthetic fill (FireLine ECO) uses 100% post-consumer recycled polyester, delivering loft, durability, and a high weight-to-warmth ratio.

• Women’s-specific cut with a gentler taper from shoulders to feet reduces cold spots.
• Fits campers up to 5'10" (165 cm) with a comfortable shoulder and hip girth.
• Weighs about 2 lb 3 oz and packs down to roughly 6 x 7.5 inches.

With a lifetime warranty, the Sidewinder SL is built to accompany many adventures, from late-season camping to nights spent on uneven ground. Consider how its side-sleeper design and warmth-focused construction might fit your next trip, without making guarantees about outcomes.