These days it seems that everyone and his cousin are making memory foam mattresses. Memory foam, introduced to the mainstream some years ago, offers undeniable advantages for sleepers. The foam conforms to the body, offering a cradle of support where your body needs it most, where traditional mattresses typically offer no support at all. However, people who sleep on memory foam mattresses consistently complain that heat builds up beneath them, making sleep uncomfortable, and they often feel like it's hard to move and change positions on their memory foam mattresses. Leave it to Simmons to come up with a new type of memory foam that takes care of both problems. NxG Advanced Memory Foam is the next generation of memory foam that is used in Simmons Bedding Company's Comforpedic range of mattresses. Created in a special sealed vacuum chamber, NxG Memory Foam is more resilient than traditional memory foam, responding more quickly to your movements to eliminate that "sleeping in quicksand" feeling. NxG Memory Foam is also designed to help dissipate heat, wicking it away from your body so that your sleep is more cool and comfortable. Only Simmons Comforpedic mattresses are made with NxG Memory Foam, touted as the next generation in memory foam comfort and support. Simmons Comforpedic mattresses come in five different ranges, each of them offering different benefits for sleeping. Each of the five ranges - the Original, the Nassau, the Mystere and the Nuvo patented sleep system - comes with a 25 year warranty. The Comforpedic collection also includes a range of pillows designed to enhance your sleeping comfort.