Your sense of time will change
When you have no sensory input, nothing to anchor you, your perception of time completely warps. In flotation therapy, where you only spend an hour or two, the mind goes deep into a slow brain wave or meditative state, and you can come out feeling like just a few minutes have passed. This effect is magnified in chamber therapy where you spend multiple days. With no night and daylight cycles to guide you, you will perceive the passing of time very differently.
This applies especially to flotation therapy. The warm saline water in combination with sound and light proof environment often causes people to experience slight discomfort and tightening in areas of the body that are often stressed. The upper back and neck are most likely candidates for this. These initial feelings of tension or panic subside quite fast and for most people, it’s enough to just shift focus to their breathing.
Many people report hallucinating
It is common that as the mind is set free from sensory input it starts wandering and creating on its own. But whether you will hallucinate or not seems to depend on your predispositions. A 2015 study divided 46 people into two groups based on how prone they were to hallucinations. Both groups had similar experiences after going through sensory deprivation treatment. But the group that was more prone to hallucinating experienced increased frequency of hallucinations.
It’s safe and well tolerated
Even though it sounds like there are a lot of weird things happening during sensory deprivation, it is safe and well tolerated based on the research we have. In regards to chamber REST, Suedfeld (1980) states that fewer than 10 % of people terminate their stay based on unpleasant experiences before the end of the basic 24-hour period. For flotation REST, Suedfeld (1999) concluded that fewer than 5 % of the subjects tested leave before the session duration ends, which is usually around an hour.
Commercial places that offer flotation tanks often have a list of conditions that don’t go well with the procedure. They might include epilepsy, kidney disease, low blood pressure, claustrophobia, and so on. It’s always good to talk to your doctor if you feel unsure. And it’s important to choose reputable places, especially if you’re planning a longer chamber REST, make sure the staff is professional and well trained.