Cooling mattress pads and covers can work in two main ways: material cooling and water or fan cooling. Some mattress pads and covers use special materials to pull heat away from your body as you sleep. These can be proprietary blends or natural materials like bamboo. Other mattress cooling systems have separate units that provide water cooling through a pad with tubes or fan cooling. These tend to be a bit bulkier and more expensive, but many offer a more precise temperature control system.