The combination of these elements creates an environment that is free from all external stimulation. Our body responds to this environment by basically taking a gigantic mental and physical sigh of relief. No longer worried about filtering the outside world to look for potential danger, our production of stress-related hormones drop to almost nothing, our brainwaves lower in frequency to a state associated with mental relaxation and free-thinking, and there is a natural spike in the neurochemicals that make us feel joy.
All of this is compounded by the inherent relaxation created by absorbing Epsom salt (Magnesium Sulfate). While used primarily in the float tank to actually make people float, Epsom salt comes with the added benefit of softening skin and hair, cleansing and detoxifying the body, and getting people the magnesium most of us are lacking.