Fix it
Sleeping Bag Not Warm Enough? Fixes (2027)
Why your sleeping bag feels cold and how to fix it: pad R-value, drafts, liners, and the mistakes that steal warmth.
A bag rated for the night's temperature should keep you warm, so when it does not, something else is wrong. In our experience the bag is rarely the problem; the pad, drafts, and damp insulation are. Work through these fixes before buying a warmer bag.
Cold from below despite a warm bag
Your pad is under-insulated. The ground conducts heat all night, and no bag compensates for a summer pad in cold weather. Match R-value to conditions: R-4 minimum for three-season use, R-5-plus near freezing. This single fix resolves most I was cold in my 20-degree bag complaints.
Drafts around the neck and shoulders
Cinch the draft collar snugly around your neck and close the hood's drawcord to a breathing hole. These features exist on all three mummy bags here and are the most underused warmth controls in camping. Wear a dry beanie; significant heat escapes from an uncovered head.
Bag feels colder than its rating
Add a liner for 5 to 10 degrees of cheap warmth, and change into dry base layers before bed; the clothes you hiked in hold moisture that chills you. Ensure the bag is fully lofted: a bag compressed in its stuff sack for months needs hours to recover, and synthetic bags like the Trestles recover slower than down.
Damp bag losing warmth overnight
Tent condensation wets the bag's shell, and wet down collapses. Ventilate the tent to reduce condensation, keep the bag off tent walls, and in persistently damp climates consider that a synthetic bag like the Trestles Elite Eco 20 is the right tool. In the morning, air the bag in the sun before packing.
Questions, answered
Should I sleep in my clothes inside the bag?
Dry base layers, yes; they add warmth. Damp hiking clothes, no; the moisture chills you. Never wear a heavy jacket inside a mummy bag, as it compresses the loft.
Does a tent make the bag warmer?
Marginally, about 5 degrees, by blocking wind and trapping some heat. The bag and pad do the real work.
When is it time for a warmer bag?
When you have fixed the pad, drafts, and clothing and still sleep cold at the rating's limit. Then size up 10 to 15 degrees, not 5.