Sleeping bag basics

You know the basics – a sleeping bag is made for you to sleep in. But there’s actually a lot more to it than that. It’s all about insulation and keeping you warm on those chilly nights. In order to keep you warm, sleeping bags trap and hold your body heat that is constantly produced. This forms an insulated dead air space. How does that happen? Well, the dead air space is a result of the type of insulating fibers used in the bag and the amount of loft they provide. Loft is the amount of air space between the insulating fibers. Think of loft as the fluffiness of the insulation. So the greater the loft, the warmer the bag will be.

In order for your sleeping bag to work most effectively, the dead air space needs to be warmed by the radiated heat from your body. But this can’t happen if you’re bundled up in extra layers of clothes. When you’re camping in really cold weather, it’s only natural to want to pile on the extra layers when you go to sleep because you think they’ll help you stay warm. Wrong. This actually keeps the sleeping bag from providing warmth. How so? Your extra clothing traps warmed air around your body like the sleeping bag is supposed to do, but the clothing is much less effective. And since the warmed air isn’t being trapped by the sleeping bag, cold air can seep in, making you feel even colder. So though it doesn’t sound right, the less you wear while using a sleeping bag, the more effective the bag will be at keeping you warm.