Most sleeping bags are filled with either synthetic or down insulation. Both have specific advantages over the other, but a down sleeping bag is generally considered the superior of the two options. "Down," itself, is actually composed of the undercoating from a bird's plumage and does not include the bird's feathers. This layer of insulation on a bird works just as it does in your sleeping bag--it keeps you warm and allows unwanted moisture to escape. Its natural properties have many specific advantages that are very beneficial to the outdoor enthusiast and are discussed below.

Advantages of a Down Sleeping Bag
The natural properties of down insulation allow it to be compressed much more than the manmade fibers of a synthetic bag. This can save much needed space in a backpack for clothes or food.

Down fill also weighs less than its synthetic counterpart. This can prove to be a large advantage for backpackers who look to shave every ounce off of their back for a long trek.

Although synthetic sleeping bags can obtain the same warmth as its counterpart, down bags provide the most warmth for the least size and weight.

Down works similar to popular moisture wicking clothing like Under Armor. When moisture is present in your bag, water can easily escape while still keeping you warm.

Synthetic fill has a tendency to lose its shape and effectiveness over time while down rarely loses its original form and will always be effective when properly cared for. Simply, a down bag can last a lifetime.

Disadvantages of a Down Sleeping Bag
Unfortunately, down sleeping bags cost significantly more than their synthetic counterparts. Down has its obvious advantages, but you will have to pay for them.

Cannot Get Wet
When using a down bag, it must be kept dry at all times otherwise it loses its effectiveness. If the sleeping bag gets too wet, it will take a long time to completely dry out. This can be easily avoided when camping by laying a ground mat on the floor of your tent and using a pad to keep your back off of the ground.

Requires Specialized Cleaning
Since down is natural, special products must be used when washing a this type of bag. It is advised to bring your sleeping bag to a dry cleaner to ensure that the it will be washed properly.

Although most down professes to be hypo-allergenic, some people can still be develop allergies to sleeping in a down sleeping bag. This is generally rare, but if you are averse to down pillows or comforters, it would be advisable to only purchase the highest quality sleeping bag.

The Verdict
A down sleeping bag is really the only choice for the avid outdoorsmen. You may save in the short run by purchasing a synthetic sleeping bag, but the down sleeping bag will almost surely last longer than its counterpart, it weighs less, and will keep you warmer.

Now, to help choose the right sleeping bag features in your next purchase, you will have many options to consider.  Among them are your frequency of use, what seasons you will use your bag, and your sleep style and size.  Be sure to read the following article to help you choose the right sleeping bag.