Author Michael Rutter offers the following tips about sleeping bags in his book Camping Made Easy:
The way a sleeping bag works is that your body does the heating and your bag holds it in. You want a bag with enough room so you can stretch out comfortably and still have a little room left at the bottom. For a child, an adult bag will not be as warm as a smaller bag, because an adult bag will have too much unheated empty space.
Bag Types
1. Mummy: a close-fitting bag, hooded around head and shoulders, lightweight and more efficient at retaining heat. You cant turn in the bag; it turns with you.
2. Semi-mummy: cut a little larger than a rectangular mummy; still retains heat well.
3. Rectangular: comfortable, room to turn and move in, warm air escapes around the shoulders. This one weighs more than mummy styles but is more comfortable.
Air out bags after every use. Store folded or loosely compressed in a dry closet or storeroom.
In cold temperatures, assure a warm nights sleep:
Wear a hat.
Have a meal, snack or drink before you snooze.
Place your sleeping bag on a sleeping pad, which insulates against the cold ground. (A couple of old blankets folded together work as a pad.)
Avoid going to bed cold. Do a little physical activity to warm your body before getting into your sleeping bag.
