Backpacking air mattresses are small, thin inflatable mattresses. The idea of sleeping on air after a long day on the trail may sound heavenly, but air mattresses are not always the best choice for backpacking. They are undeniably comfortable, but they have several drawbacks. The first is the possibility of leaks. Backpackers put their gear through a lot of stress, and even a durable air mattress can spring a leak. Leaks are a pain to fix in the field, especially at night, but if you don't fix it, you'll be sleeping on cold, hard ground. Backpacking air mattresses also do a poor job of insulating to begin with. The large, open space of air inside the mattress chills to outside air temperature and circulates that air underneath you. Thus most backpacking air mattresses are only suitable for warm-weather use. Some backpacking air mattresses remedy this problem by adding insulation to the mattress. For example, the Exped Downmat is an air mattress filled with down. The stuff sack doubles as air pump, and you can also use it as a pillow. Handy!
The backpacking air mattress you take with you, unless you have a friend along who likes carrying your gear, will be have to be carried by you; therefore, one that is lightweight is a consideration that must be addressed.
Taking along a adds to the weight you have to carry. Having a backpacking air mattress that is easy to inflate is a bonus (having good lung power helps); otherwise you will probably not use it. If you are not going to use your backpacking air mattress, then why did you bring it?
Now that you know why a sleeping pad is a necessity, you need to know what kinds of pads are available so that you can choose the one that's right for you. There are four types of backpacking sleeping pads on the market today: backpacking air mattresses, open-cell foam pads, closed-cell foam pads, and self-inflating pads. Each type of sleeping pad has its pros and cons.