Memory foam mattresses are known for their sensitivity to temperature.

Viscoelastic or memory foam was originally created for NASA at the NASA Ames Research Center.
Although it was never used in the space program, it was used to make aeroplane seats more comfortable and safe for passengers and pilots. Later, it was used in medical applications, such as for patients who had to stay in bed for very long periods of time without moving and who developed pressure ulcers or sores and even gangrene. The viscoelastic mattresses were very useful in stopping this from happening.
Initially, this material was very expensive, but decades later the production was optimized and products were developed that, although still exclusive, are available to everyone, such as mattresses, pillows, cushions, etc.
The most important property that this material has is that it dissipates the pressure of the body in a uniform way in all its surface. This means that the body, when lying down, does not have points where the pressure is very high (head, shoulders, hips), but rather the material moulds itself to the whole body and dissipates the pressure evenly.
This material is mainly used for making pillows and mattresses. These products come in different densities and levels of firmness.
Density of the viscoelastic
Density is the amount of material found in each cubic meter (Kg/m3). Based on this density, the viscoelastic mattresses offer one performance or another, that is, more or less viscosity and elasticity to accommodate the body.
In general, the higher the density, the higher the degree of adaptability, translating into comfort and durability.  When the density is high, it means that there is less air inside the mattress, which is associated with a longer duration of the mattress.
The densities correspond in the following way: the low density ones have visco-elastic nuclei around 18-40 Kg/m3. Those of medium density have them of 40-80 Kg/m3 and those of high density when it exceeds 80 Kg/m3.