KEEP YOUR SLEEPING BAG DRY. A wet sleeping bag is not only uncomfortable but it is also less effective at keeping you warm. Wrap your sleeping bag in a plastic garbage bag before you place it in its stuff sack. Make sure you brush the snow off your clothing and boots before you get into your tent. (A little whisk broom works great for this.)
SPREAD OUT YOUR SLEEPING BAG AT LEAST 1/2 HOUR BEFORE BED TIME. Give your sleeping bag at least one half hour to fluff up before you get inside. The loft of your sleeping bag is what helps keep you warm.
WEAR A HAT AND SCARF TO BED. Heat escapes rapidly from your head. Wearing a comfortable stocking cap is one of the best things you can do to keep yourself warm while you are sleeping. Wrapping a scarf around your neck will also help you retain your body heat.
CHANGE YOUR CLOTHES BEFORE YOU GO TO BED. During the day, your clothes collect your body's perspiration. If you go to bed in the same clothes you were wearing during the day, that perspiration will cool your body off. Put on dry clothes before getting into bed. Put on extra clothes if it is extra cold.
USE A SLEEPING PAD. The greatest source of cold when you are sleeping is the ground, not the air. Use a foam sleeping pad to insulate you from the ground. An air mattress will not work. The more insulation the better. In the winter, a half inch to an inch of insulation is ideal.
TAKE A HIKE BEFORE YOU GO TO BED. A sleeping bag does not warm you. It only helps you retain the heat that your body generates. Before you get into your sleeping bag, get your internal furnace running by taking a walk or doing a few jumping jacks. Don't work up a sweat! That will only make you colder.
EAT A SNACK BEFORE YOU GO TO BED.You need fuel in your furnace. Before you go to bed, have a snack. Proteins, such as cheese, nuts, or grains, are better than simple sugars. Proteins release their energy more slowly than sugars, keeping you warmer through the night.
PUT TOMORROW'S CLOTHES UNDER YOUR SLEEPING BAG. If you put tomorrow's clothes between your sleeping pad and your sleeping bag, your clothes will be warm when you go to put them on the next day. Plus, the additional layer between you and the ground will help you keep warm.
USE A BLANKET OR A SECOND SLEEPING BAG FOR EXTRA INSULATION. Increase the warmth of your sleeping bag by adding a blanket or by double bagging.
SLEEP WITH YOUR FACE OUTSIDE OF YOUR SLEEPING BAG. Don't cover your face with your sleeping bag. Your breath contains moisture that will moisten your sleeping bag and chill you.