Some people who want to relax get a massage. Some meditate during yoga. And others float in
a pitch-black, saltwater-filled isolation tank.

Cue record scratch! You might be wondering what is a float tank? In short, it's a way to experience
sensory deprivation, and though it sounds a bit odd, for some people it can be the secret to
overcoming pain or writing the next great British novel. If you're hesitant about plunging into
a flotation tank, we addressed some questions you might have to help give you a better sense
(pun sort of intended) of what float tanks and sensory deprivation are all about.

What is a float tank?

Also known as an isolation tank or sensory deprivation tank, a float tank is a soundproof,
lightless tank filled with body-temperature salt water that's designed to block out all
distractions and create a feeling of weightlessness.

What is sensory deprivation?

Sensory deprivation is exactly what it sounds like: the act of depriving your senses of external
stimuli. Technically speaking, the term can be applied to the deliberate restriction of any one
sense. Wearing a blindfold, for instance, would be considered a form of sensory deprivation.
However, the term is mostly used to refer to the restriction of several—if not all—of the
senses at once.

Why … would I want to do that?

Sensory-deprivation therapy is often referred to as restricted environmental stimulation therapy,
which is shortened to REST—and for good reason. While floating in an isolation tank, the
postural muscles can fully relax, something they can't even do during bed rest (you
frequently need to adjust for adequate blood flow). Therefore, the body is able to rest in
a way it's otherwise unaccustomed to.

But REST's most significant benefits happen in the brain. A typical sensory deprivation tank
experience lasts about 90 minutes; studies have shown that, in the last 20 minutes, the brain
switches from alpha and beta brain waves to theta brain waves, which are usually only present
in the brain at very select times, most notably during REM sleep. During the theta state, your
subconscious typically works through problems, which can promote a period of enhanced
creativity. This state is also unique in that those experiencing it are able to achieve very deep
relaxation while remaining conscious of their surroundings.

What are some of the possible benefits of this type of rest?

Many people who float are hoping to reap specific benefits beyond general relaxation. Because
the theta state is where creativity and problem-solving occur, flotation REST is of interest to
artistic types or anyone struggling to work through emotional or mental blockages.
(Jurassic Park author Michael Crichton was a reported fan of using flotation tanks to overcome
writer's block.)

Others may be more interested in the physical benefits of flotation REST. Some studies have
shown that endorphin levels are higher during floating, which may provide pain relief. Others
have indicated that cortisol levels are reduced, leading to a decrease in stress. Some controlled
studies have also suggested that flotation therapy may be beneficial to those trying to quit
smoking or abstain from drugs or alcohol.

What's the deal with the salt water? Couldn't I just lie down in a dark room?

As we mentioned, floating has many benefits, one of which is that the postural muscles completely
relax in a way they can't manage while in contact with a surface like a bed or the floor. If total
(or near-total) numbing of the senses is what we're after, then floating is the best option.

Is it possible I could drown?

No! This is where the salt comes in. The earliest flotation tanks required submerged users
to wear a special suit and mask so they could breathe. Obviously, it wasn't an ideal situation.
The suit and breathing apparatus were uncomfortable and difficult to use, hindering the
floater's ability to truly relax.

Today's tanks use a high concentration of Epsom salts to drastically increase the density of the
water, making it essentially impossible for you to turn over or drown. The water is also kept right
at skin temperature so users will not feel the boundary between the parts of their body that are
underwater and those that are exposed to the air.

This all sounds great, but are there any drawbacks?

Many isolation-tank users report feeling a bit uncomfortable during their first float, and
it's not unusual to experience itching throughout the body for the first half of your time in the
tank. Others might feel confined in the dark tank—if that happens to you, just remember you
are in control and can leave at any time.