A sensory deprivation tank, commonly known as a float tank, is a light-proof and sound-insulated environment where a person floats effortlessly in a shallow pool of water. This environment is created by dissolving hundreds of pounds of Epsom salt (magnesium sulfate) into the water, resulting in an extremely dense solution. Proponents of float therapy claim that soaking in this highly concentrated solution allows for significant magnesium absorption through the skin, bypassing the digestive system. This raises the central scientific question: does the float tank environment truly make transdermal magnesium absorption measurable and effective?
Understanding Transdermal Magnesium Absorption
The skin is primarily designed to function as a barrier, not as a transport system. The outermost layer, the stratum corneum, is a tightly packed layer of dead cells and lipids that serves as the body’s main defense. For a substance to penetrate the skin and reach the bloodstream, it must typically be small and fat-soluble. Magnesium sulfate is an ionic compound, meaning it is neither fat-soluble nor particularly small. This makes it difficult for magnesium ions to move efficiently across the intact stratum corneum. While some research suggests magnesium ions may penetrate through hair follicles and sweat glands, these represent a very small percentage of the total skin surface area. The skin’s robust barrier function creates scientific skepticism regarding claims of substantial transdermal absorption of minerals like magnesium.
Factors Influencing Absorption in the Float Environment
The conditions within a float tank may enhance the potential for magnesium absorption. A typical float tank contains between 800 to 1,200 pounds of Epsom salt dissolved in water, which is far more concentrated than any home bath. This extreme saturation creates a powerful concentration gradient between the high magnesium level in the water and the low magnesium level in the body, which is the primary physical force driving potential absorption.
The water temperature is another important factor, as it is typically maintained around 93.5 to 95 degrees Fahrenheit (34 to 35 degrees Celsius), matching the external temperature of the skin. This warmth can induce a slight vasodilation, or widening of blood vessels, near the skin’s surface. Increased peripheral circulation may theoretically improve the uptake of any magnesium ions that successfully penetrate the skin barrier.
The duration of the session, commonly 60 to 90 minutes, also provides extended exposure to the highly concentrated magnesium solution. This prolonged contact time may allow a slow, passive diffusion of magnesium ions to occur across the stratum corneum. Additionally, the sheer density of the salt solution creates an osmotic pressure that might also influence the movement of water and ions across the skin, although the net effect is complex and debated.
Measuring Magnesium Uptake Post-Float
Studies attempting to measure absorption typically involve testing serum (blood) or urinary magnesium levels before and after soaking in Epsom salt solutions. One non-peer-reviewed pilot study suggested that soaking in an Epsom salt bath daily for seven days resulted in a measurable increase in both plasma and urinary magnesium levels in most participants.
However, the scientific consensus remains cautious; while some absorption likely occurs due to the unique float tank environment, the amount is highly variable and not precisely quantifiable for the average person. The extent of absorption appears to be significantly influenced by individual factors, such as a person’s existing magnesium status. Those with lower baseline levels may show a greater increase in urinary excretion, suggesting clearance of the absorbed mineral by the kidneys. The evidence does not reliably prove that floating is an effective method for correcting a severe magnesium deficiency compared to controlled oral supplementation. Ultimately, the skin’s robust barrier function ensures that absorbing dangerously high levels of magnesium through floating is highly unlikely, providing a wide margin of safety.