Floatation tanks (also known as sensory deprivation, immersion therapy tanks, or isolation baths), are lightless, soundproof chambers in which a person floats in a shallow depth of salt water fluid. The fluid is typically between 12-18 inches deep and consists of a near-saturated (25-30% by weight) mixture of potable water and Epsom salt (magnesium sulfate, or MgSO4). Typically the water is heated to 34-37°C, both to match the user’s body temperature and allow sufficient dissolution of the high concentrations of salt.2 The water does not normally contain a chemical disinfectant (e.g. chlorine or bromine), although water may be recirculated through a filtration unit between users. The high salt concentration allows users to float with minimal effort by creating a saline environment 1.2-1.3 times denser than pool water. Most tanks are designed to be enclosed, relaxing, and virtually stimulation-free environment.
In recent years, the recreational use of floatation tanks has grown in popularity as a form of stress reduction. Literature in alternative medicine has identified Floatation-REST; (Restricted Environmental Stimulation Technique) as a “one-hour session in a tank containing water with a high salt content (approximately 30%) and maintained at 35°C”.7 A meta-analysis by Dierendonck and Nijenhuis concluded that floatation-REST has an impact similar to other more popular stress management techniques, such as meditation. 8 Although floatation tanks are available for purchase by the general public, most floatation tank users visit centers that offer the service for a fee.”7
Bathers lie face up, floating on the water’s surface. Generally only one individual will float at a time, however partner floatation does occur.9