A sensory deprivation tank, also called an isolation tank or flotation tank, is used for restricted environmental stimulation therapy (REST). It is a dark, soundproof tank that is filled with a foot or less of salt water. The water in a sensory deprivation tank is heated to skin temperature and nearly saturated with Epsom salt (magnesium sulfate), providing buoyancy so you float more easily. You enter the tank and are cut off from all outside stimulation, including sound, sight, and gravity when the tank’s lid or door is closed. As you float weightless in the silence and darkness, the brain is supposed to enter into a deeply relaxed state. Sensory deprivation tank therapy is said to produce several effects on the brain, creativity, and managing anxiety.