The problem with memory foam is twofold. While it offers a soft, cushiony feel to sleep in, its ability to absorb heat and breathe makes it a hell of a choice for long use. Thick layers of foam act as an impassable barrier causing the heat and moisture from our bodies to build up. This makes it extremely uncomfortable to lie on for long. Because the memory foam reacts to heat, it can feel too hard in cold and saggy when it’s warm.