Remember you cannot use an electric under blanket with Memory Foam.The foam needs to react to your body heat to respond to your body shape.Many people find these mattresses warmer this is because a much higher proportion of your body is in contact with the sleeping surface thus reducing air circulation.However I am normally a hot sleeper and since changing to memory foam have not noticed a great difference.I think the benefits far outweigh a few hot nights in the peak of our summer.