Women's sleeping bag design began in 1995 when Sierra Designs single-handedly developed the category.Sierra Designs redistribute the insulation in the case of the Sunshine, premium 800-fill goose down to provide additional warmth through the torso and footbox, where Sierra Designs researched into women's sleep patterns indicated. Waterproof-breathable DriZone creates an impregnable barrier to the elements, while tuck stitchingprotects seams from abrasion and forms a more weatherproof seal. The Sunshine boasts an attention to detail, with Pad Locks,Snag Free Zipper Tracks, and an ergonomically shaped foot box.

An ergonomically shaped foot box facilitates a good night's rest by allowing feet their most natural position during the night.