Traditional sleeping bags used to be nothing more than a folded over wool or cotton blanket that was held together by a zipper. Today's sleeping bags go through rigorous field testing before they are sold. They have seen an advancement in everything from the texture they are made of to their ergonomic design features.

New designs usually will contain a nylon outer shell that can be diverse in its characteristics. The nylon can be either fragile or sturdy, conducive to heat or not, and slim or thick. Some can offer total protection from water, while others only a partial delay in getting soaked. When choosing a bag, look for tight seams with strong edges.

The interior of sleeping bags has changed over the years, with more and more offering superior insulating materials. Some weigh as little as an ounce per square yard. Primaloft, Dupont Thermolite and other synthetics has made it possible to produce a lightweight bag that really keeps the cold out, while still allowing the interior to breathe.

Clever design has been added to ingenious materials in many models. Those that offer layered synthetic insulation with natural (or even synthetic) down provide excellent temperature control and great comfort. Fill is measured by a number, with 750 now the bottom for a good bag, 900 is better. The number represents the volume occupied by a single cubic ounce of material. Use it to compare bags.

Materials aren't the only thing that's important. Geometry has really been improved in contemporary designs. A full length zipper is important on those nights when it's warm and you want to let a little air in. But having a well shaped mummy hood and draft collar are big advantages on those nights when you don't.

The mummy hood helps keep your arm warm if you're the type to put it under or above your head. It's also designed to allow you stuff clothes and towels beneath a liner to make a pillow. At the other end, space has been expanded in some models to allow those who sleep on their backs to keep their toes pointing up in a comfortable position.

A bag should keep the cold ground out of the bag while allowing you to move freely. Those characteristics are hard to obtain together, but modern designers have accomplished just that.

At the same time, you want that bottom layer to provide sufficient padding when you don't have an air mattress or cot. Some models accomplish that with a slide-in rollable pad, others have the padding built in. Look for ones that provide adequate comfort without adding excessive weight and bulk.

To get the most out of your camping trip, you want to be sure to not forget your sleeping bag. Some will argue this is the most important camping equipment you will need. If you want to enjoy those adventurous hikes then getting a good nights sleep is key. A sleeping bag will provide you with the comfort and rest that you need to truly enjoy you camping experiences.