First Impressions of a Sensory Deprivation Tank

Content warning: unapologetically first-person perspective; smattering of objective stuff at the end.

My friend and I were sitting in the hippie-vibes foyer sipping water from tiny ceramic mugs. Dream catchers dangled across from us and ambient New Age music was subtly setting the mood. A guy with damp hair emerged from a corridor, having just completed his first session. The receptionist looked up to ask how he’d found the experience. He had gotten motion sickness.

“The first time’s a write-off for everyone,” she informed him consolingly, immediately glancing at us and apologising.

His more elated girlfriend soon emerged, and it was now our turn. This is the contraption I was to get into, the Apollo model:


The picture gives a misleading impression of smallness. The Apollo was sizeable and chunky and felt like serious business.

I went through the prescribed protocol of showering and jamming in a set of earplugs, then slid back the lid of the tank. I stood there nakedly, gazing into its dark watery depths. The prospect of getting in suddenly felt both daunting and somehow undignified. But in I gingerly stepped, heedful not to slip over in the shallow water, extra slippery with its 400kg infusion of magnesium sulfate, AKA Epsom salt. Get water that salty in your eyes or mouth and it will feel like a mild acid burn.

I tugged closed the lid from the inside. Lying back, steadying myself floating near the surface of the water, I shut my eyes, and pushed the button to kill the light.

The water is lukewarm, the air humid. The ambient music plays on soothingly.

I direct my attention to the breath, as suggested by the receptionist, and try to focus. The music gradually fades away, leaving me alone with myself. In that rarefied space, the movements of my lungs, something normally unnoticed, sounds like some awful strenuous struggling creation. In fact, more than a little like…


My neck aches a little and I realise I haven’t been entirely trusting the water. I turn the relaxation up a notch and surrender fully to its queer cushioning buoyancy. Apparently lots of people discover unknown tensions and aches in float tanks that they’ve been carrying around.

Sensation starts to slip away from my partially-submerged limbs. There is no claustrophobia – if anything, the quiet watery blackness expands in my mind. I imagine (…or is it rather feel?) myself floating on some immense motionless ocean. A subtle persistent current starts tugging me to the right, and I anticipate the collision with the side of the tank – it never comes. Just a little perceptual hallucination, I think to myself. The current dissipates (returning some time later as a peaceful ebb and flow, like the in-and-out swell of a calm ocean).

My sense of body continues to retreat, and the mind seizes the opportunity to venture further into surreal Dali-esque environments. I visit some quite strange places.


Is that the sound of an ocarina in the distance?

*          *          *


Ok brain, that’s enough now

However, with physical processes like heaving lungs, swallowing, and occasionally brushing against a wall of the tank, it’s impossible to lose sense of the body for too long; I return to myself.

Minuscule bubbles begin creeping from an earplug to zip up the side of my face, triggering bursts of sensation that seem totally inappropriate for the bubbles’ piddling size. Remove input to a sensory organ, and the sensitivity increases, huh?

I find myself vividly reliving a forgotten memory. Years earlier, I once ended up floating in a lonely patch of the Dead Sea with a small group of near-strangers, all of them older than me. Due to the intense buoyancy it‘s impossible to remain upright, so we bobbed about on our backs. We were 300 meters below sea level, and I imagined looking up and seeing the surface of the ocean glittering far above in the sky. A middle-aged man had just opened up to me, unprompted, about his recent diagnosis of Parkinson’s disease. I could feel his distress hidden behind the stoicism. What do you say in a situation like that? What do you say to the inexorable creep of neurodegeneration? From someone you barely know, no less. In the background, one of our crew floated on his back reading a newspaper, fulfilling (I was sure) a frivolous long-held fantasy. It all felt absurd.

Back in the present, the bubbling earplug births itself from my ear and floats out into the darkness of the tank, never to be seen again. This incites me to attend to my sense of hearing and I discover… absolute silence. The actual sound of silence, which I have truly never before heard in my life. Even hearing nothing is not actually silence, so it turns out.

Further quirky sensory experiences follow one another. I start giggling, uncontrollably, about a dumb old memory of a friend’s guitar falling out of its case. I have no idea why. I swish my fingers about in the water. There is feeling there, but I could be in a cloud, or formless void for all I can tell. I touch my legs, and find I am smooth and oily like a fish.

At some point I realise I have the option of opening my eyes, so I try it out. Absolutely nothing in my visual field changes. There are, seemingly, zero photons in the tank. This piques my interest in the random static noise pixels that one always sees when the eyes are closed. If I am in pitch blackness, and the random static looks the same with eyes open or closed, they must be artefacts of my mind! A patch to the far right of my “sight” starts flickering white on black – is this a trace of raw neural firing in my skull, leaking into consciousness?!? Where else could it be coming from?

I drift into a bizarre hypnagogic semi-dreaming, semi-awake state. It’s unclear if I drift off at some point, and if so for how long. Time has lost all meaning. I idly remember the existence of boredom, almost as an abstract concept that I learned about as a child. I ponder the satisfactoriness of merely existing in this tank. Surely it would be possible to get bored at some point, I figure, but how long would it take? How would you even know? Imagine being blind and deaf in the world, or in a coma. Would it feel anything like this, locked off from everything in your own mind? Imagine being a brain in a vat, with the world just a simu –


And then that ambient music is fading to life again, and I’m suddenly ready to leave, and am letting the water drip away from my eyes, and stumbling back under the shower to wash the incredible crust from my hair.


A modicum of actual research into floating

Unlike prolonged or involuntary sensory deprivation, which can lead to extreme anxiety, terror and hallucinations; floating in an isolation tank, also referred to somewhat charitably as “Restricted Environmental Stimulation Therapy” (REST), is supposedly beneficial for relaxation and meditation. Alternative “medicine” practitioners and float venues also tout a whole bunch of other putative benefits, but be sceptical in your expectations: while I found the experience extremely interesting, almost none of these supposed health benefits have been rigorously demonstrated.

For example, ostensibly, toward the end of a decent float the brain transitions to theta waves, which is the state that occurs right before falling sleep and upon waking. I did enter a bizarre pre-dreaming state at some point – but maybe people just get sleepy when lying in the dark for an hour. Has anyone actually strapped EEGS onto floating people’s scalps? Another common belief holds that Epsom salts somehow get absorbed through the skin and ease muscle pain. This is entirely unproven, and almost certainly only a minor effect even if true.

For all the cynicism though, quite a lot of research has actually been conducted on floating. Research dates back to at least the fifties, and there are some apparent benefits. However, that being said, most of the studies use depressingly small sample sizes and are terribly controlled for (hint to future floatation researchers: “being on a waiting list” is not a good comparison group for “getting a comfy uninterrupted lie down for an hour”). In any case, a decent index of what journal papers there are can be found here.

So with all those caveats, floatation maaay help to some degree with such things as:

  • Lowering stress, depression, anxiety, and worst pain; increasing optimism and sleep quality [1]
  • Lowering levels of cortisol/stress, and lowering blood pressure [2]
  • Alleviating severe chronic pain, reducing depression and facilitating sleep in these individuals [3]
  • Providing a conducive environment for breaking addictions [4]
  • Uh, jazz improvisation? [5]

Whether or not any of these effects are real, or more effective than just lying down thinking for an hour, the perceptual effects are pretty indisputable. So if you consider yourself interested in your own consciousness, floating is an experience worth trying out at least once. If you’re still not convinced, a little known fact: Richard Feynman once met John Lilly, the inventor of floatation tanks, and thereafter started tripping on ketamine and doing floatation sessions in order to induce hallucinations. That’s good enough for me.

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