Build a camp sleep system: pad, bag, pillow and shelter that work together

People often buy a sleeping bag, check the temperature number and assume the job is done. Then they spend a cold night shivering on a thin pad. A sleep system treats everything between you and the outdoors as one set of parts: the pad under you, the bag or quilt over you, a pillow, your clothing and the shelter around you. When the parts work together, you sleep warm and wake up rested.

How you lose heat at night

Four mechanisms matter outdoors:

1. Conduction. Heat flows from your body into the cold ground or cot under you. Insulation compressed beneath you does very little, so the pad does this job.
2. Convection. Moving air strips warmth from you, from drafts in the tent to wind under a hammock.
3. Radiation. Your body radiates heat to cold surroundings. A bag or quilt, and a tent, hold that heat in.
4. Evaporation. Sweat and damp clothes carry heat away as they dry. Moisture is a major cause of feeling cold.

Good gear tackles all four. A pad with a high R-value limits conduction, a bag with enough loft limits radiation and a sheltered, ventilated tent limits convection and condensation.

Part 1: the pad

Your pad is the foundation, and for cold weather it often matters more than the bag. R-value measures insulation, and most pads are tested to the ASTM F3340 standard, so ratings can be compared. Common guidelines are about R1 to 3 for summer, R3 to 5 for three seasons and R5 and up for winter. Use our R-value picker to estimate what you need, and read the pad category page for types and sizes. You can stack pads, and their R-values roughly add, which makes a closed-cell foam pad under an air pad a cheap winter upgrade.

Part 2: the bag or quilt

Sleeping bag temperature ratings are the most misunderstood numbers in camping. Some bags are tested to an international standard, ISO 23537, which replaced the earlier EN 13537 and reports figures such as a comfort rating and a limit rating, which are not the same temperature. Other ratings are set by the maker without independent testing. Treat any rating as a guide to compare bags, and choose a bag rated for temperatures lower than the coldest night you expect, because individual people vary, and a bag at its limit is meant to keep you alive, not comfortable.

• Down is light, compressible and warm for its weight, but loses insulation when wet unless treated.
• Synthetic insulation is cheaper, dries faster and keeps some warmth when damp, but is heavier and bulkier.
• Quilts drop the bottom insulation, relying on the pad for that job. They are light and flexible but can let drafts in.
• Fit. A bag should be snug enough that there is little dead air to heat, but not so tight that it compresses the insulation. A zippered draft tube and a hood help in cold.

Part 3: the pillow

A pillow that fits keeps your neck aligned and reduces tossing and turning. See the camping pillow guide for types. In cold weather, a pillow is a place where heat escapes from your head, so a hood and a hat help.

Part 4: clothing and extras

• Sleep in dry clothes kept for the night, rather than the sweaty layers from the trail. Change before bed.
• A hat is one of the easiest ways to add warmth.
• Dry socks help, but avoid anything tight that cuts off circulation.
• A liner adds warmth, keeps the bag cleaner and can be washed.
• A warm water bottle is an old trick. Fill a hard, heat-safe bottle with hot, not boiling, water, make sure the lid is tight and put it in the foot of the bag. Check the bottle's maker instructions on temperature limits.
• Eat and drink before bed. Your body needs calories to make heat, and a snack can help.

Part 5: the shelter

A tent, tarp or hammock changes the temperature slightly, but its biggest job is blocking wind and rain. Pitch with the door away from the wind, keep ventilation open to reduce condensation and avoid touching the walls with the bag. In desert country, a tent also keeps out insects and blowing sand. For a hammock, you need insulation under you, because a bag compresses under your body. See hammocks and stands.

Three example systems

These are starting points, not promises. Wind, humidity and your own metabolism change the picture.

Fixing a cold night

If you wake up cold, try these in order:

1. Add insulation under you. Slide a spare jacket, a foam pad or a pack under your torso.
2. Add layers, including a hat and dry socks.
3. Eat something and drink a warm drink.
4. Check for drafts. Cinch the hood and close the zipper.
5. Stay dry. If your bag is wet, change into dry layers.
6. Move, with a few minutes of exercise, then get back into the bag.

If you are shivering uncontrollably, confused or clumsy, you may be hypothermic. Get warm, get dry and get help.

Common mistakes

1. Focusing on the bag and ignoring the pad.
2. Wearing damp clothes to bed.
3. Buying a bag at the edge of its rating.
4. Closing every vent and getting wet from condensation.
5. Overheating and sweating, which makes you cold later.