Some of the most common complaints from memory foam mattress owners are their heat retention, initial odor, and their tendency to sink or sag as time goes by. As previously mentioned, memory foam mattresses can get warm very fast because the foam absorbs heat quickly with little airflow. To combat this issue, look for memory foam mattresses with cooling technology or purchase a mattress protector to cool it down. Memory foam can also hold an odor when first opened, known as “offgassing” so it is recommended to let the mattress breathe without any sheets for a couple of hours up to a full day. Lastly, extreme sinking or sagging is common amongst these mattresses and often indicates that it needs to be replaced. If this begins to happen, it’s probably time to consider purchasing a new mattress.