Don't get cold feet at the prospect of winter backpacking. With the right insulation, food, and clothing, even chilly sleepers can snooze soundly through a freezing night. Follow our field-tested advice and set up your sleeping bag as shown below to create a comfortable cocoon that dries your damp clothes with body heat, and ensures all-night warmth.
Size your sack You don't need a -40°F bag to sleep toasty, but you do need a snug fit; a too-big bag means extra space to heat, which saps your body's energy. Choose a winter bag with just enough tossing-and-turning space, and a temperature rating based on the lowest digits you'll experience, subtracting 10 degrees (15 if you sleep cold).
Have a snack Eat energy bars before bed to give your body the fuel to stay warm, and keep a Snickers handy in case you wake up chilled before dawn.
Cover your dome Always sleep in a hat, especially if you don't use your sleeping bag's hood.
Dress for space It's tempting to wear every layer to bed, but too much clothing can make your bag tight and compress the insulation. Adjust your layers to suit your bag's interior volume.
Put on dry socks If your feet get cold, wrap them in a jacket or extra insulating clothes.
Snuggle with a bottle Fill a Lexan bottle or two with hot water, stuff them inside a sock or fleece, and place them between your legs (to warm the blood in your femoral artery) and at your feet.
Go long with your pad Skip the ultralight summer shortie for a full-length mat, and back up any self-inflating pad (1.5 inches thick is optimal) with a closed-cell foam mat or spare clothing underneath it. A pack placed under your legs also provides insulation.
Dry your shoes Stash wet boots in a waterproof stuff sack or trash bag between your legs to keep them from freezing. Remove insoles and put them in your bag to dry out. If you have double boots, sleep with only the liners.