A mattress topper made of memory foam gives your bed an extra velvety layer that contours to your body and creates a feeling similar to being encased in a cloud as you sleep. However, the cold weather makes it difficult for the foam to release the indentation left by your sleeping form. Additionally, if you place the topper on top of a lumpy or sagging mattress, it imitates the shape of the mattress just as easily as it does your body, resulting in a lumpy surface that is uncomfortable to sleep on. Take on the challenge from not one but two directions to get the greatest outcomes. Treat the underlying problem that is generating the uneven surface, as well as provide the memory foam the room it need so that it may restore its form.