Memory foam is so special because it conforms to the body, but this conformity also tends to trap in heat and leave little room for the body to breathe. Memory foam is very dense, and when it fits the body like a glove, you may end up sweating all night. Fortunately, some companies have taken steps to prevent this heat buildup, such as using breathable covers. SleepAid has patented a useful technology called Heat Reduction Channels. These channels are grooves cut into the mattress surface that allow air to circulate and the body to breathe. This way, memory foam mattresses don't have to be hot at all.