A mummy bag is a type of sleeping bag which narrows at either end to conserve heat, causing it to look slightly like an Egyptian mummy case. Many manufacturers of sleeping bags make mummy bags, which are usually rated for extremely cold weather. A variety of materials are used to make mummy bags and liners, to meet varying consumer needs. Consumers can order mummy bags directly from the manufacturer, or visit an outdoor supply store to acquire one.
The narrowed bottom of the mummy bag prevents heat loss through the feet. The top of the bag usually features a hood, so that the sleeper's body can be covered from head to toe, usually with a small opening for the face. The side of the mummy bag zips up and down, like a regular sleeping bag, allowing people to get in and out easily. Because of the highly heat efficient design, mummy bags are the sleeping bags of choice for very cold environments.
A basic mummy bag is usually made from water resistant material stuffed with down or polyfill and quilted so that the stuffing will not settle in clumps inside the sleeping bag. Depending on the filling and textiles used, a mummy bag may require special laundering techniques. Many companies encourage the use of a sleeping bag liner that can be easily washed, allowing people to keep their sleeping bags sanitary. Sleeping bag liners can be made from cotton, flannel, or synthetic materials. In warmer weather, some people like to sleep in sleeping bag liners, using the mummy bag as a floor pad.
The design of a mummy bag is usually highly compressible, so that it can be packed into a very small sack. This also leaves a camper with plenty of room to pack other vitally needed supplies such as food, water, and a cookstove. The bags come in assortment of colors, and some campers also stick identifying tags onto their mummy bags to avoid any confusion.
Like all sleeping bags, a mummy bag will last longer if it is well cared for. After camping, the mummy bag should be aired out before being stowed away. If the mummy bag got wet, it should also be laundered to ensure that the filling is clean and dry, so that no mold will grow inside the sleeping bag. Many manufacturers offer a warranty, so that if the bag becomes torn or damaged in some way, it can be sent back to the factory for repair or replacement.