At lower temperatures, the mattress is firmer. While at high temperatures it becomes softer and more elastic. Some memory foam mattresses however have broader temperature ranges meaning they work well in a variety of climates.
A large advantage to the memory foam mattress is that it has a high resistance to parasites. This is great for people who suffer from respiratory problems or have allergies.
Memory foam mattresses allow your body to sink into foam, creating a mold of your body. The only thing you feel is a bed of softness without the nuisance of springs in your back.
In regular box spring beds it can be difficult to get comfortable in just any position. With a memory foam mattress, no matter how you choose to position yourself, the mattress conforms solely to your body.
Regular spring mattresses can eventually start to sag in places, especially the middle. When this happens the mattress typically gets flipped over. With a memory foam mattress you no longer have to worry about sagging or the hassle of flipping it over as it simply conforms to your body weight.