Memory Foam Mattresses

Memory foam was originally developed by NASA in the 1960s for seat cushioning, and its application in mattresses became one of the more significant shifts in consumer sleep products. Understanding what it actually does, and where it has limitations, helps you make a better buying decision.

The defining characteristic of memory foam is its viscoelastic response to pressure. Unlike pocket springs that push back immediately, memory foam compresses slowly under the weight of your body and stays compressed until the weight is removed, then gradually returns to its original shape. This slow response means the foam moulds closely around the contours of your body rather than simply supporting the points where you make contact.

For side sleepers, this is particularly beneficial. The shoulder and hip are the two heaviest and most prominent points when sleeping on your side, and they create significant pressure on a firmer surface. Memory foam allows these areas to sink in further while the lighter areas of the body, like the waist, are still supported, which helps keep the spine aligned horizontally.

The main limitation of traditional memory foam is heat retention. The dense, closed-cell structure that gives memory foam its pressure-relieving properties also restricts airflow. Most modern memory foam mattresses address this with open-cell foam formulations, gel infusions, or breathable cover fabrics, which reduce heat retention compared to earlier designs, though they rarely fully eliminate the difference compared to pocket sprung.

Memory foam also responds to temperature, becoming softer in a warmer room and slightly firmer in a cooler one. For those who want the pressure-relief benefits of memory foam alongside the breathability of springs, a hybrid mattress is worth considering as the best of both constructions.