Bag ratings. Sleeping bags are “rated” to their lowest comfortable temperature.  Keep in mind that “comfort” is a relative term, so use these ratings as guidelines, rather than absolutes. These ratings are often optimistic, so cold sleepers should purchase a bag that has a more generous rating. Use the ratings as guidelines rather than absolutes.

Consider a liner. Consider purchasing a fleece liner that can add up to 15 degrees extra insulation to your bag without much bulk.  The liner is also easy to throw in the washing machine when you get home.

Indulge yourself. Your body needs sufficient carbohydrates to stay warm at night, and sufficient fats to metabolize these carbohydrates effectively.  Half a peanut-butter bagel and some hot chocolate will give your body the fuel to stay warm all night.

Warm up before getting in. Sleeping bags keep you at the same temperature you were when you got in.  Don’t put a cold body in a sleeping bag.  Do some sit-ups or jumping jacks to get your blood moving before you get in your sleeping bag.

Breathe OUT. It’s tempting to breathe into your sleeping bag to warm it up – but it’s a bad idea.  The moisture in your breath reduces the loft of the insulation and makes you colder over time.

Clean Up. Some swear there is extra warmth after washing the body and wearing clean clothes.