Do you know how deep the darkness goes? No. Chiaroscuro black conceals all but what's divulged by echoes, and figments spastic minds reveal.
Category Archives: Sensory Deprivation
Tomb of the Diver [Lyric Poem]
Plunging into darkness, there is no other way. In the tomb-like silence, the mind begins to stray. To roam, to roam, to roam, or does it simply sink; with neither light nor eyes, one might just be hoodwinked.
Black Hole [Kyōka]
deep in the cave,
there’s a hole that knows no light;
and nothing can reside
within that black hole
My Year of Discovering How Weird the Mind Gets, Pt. II [the Tank]
This is the second installment in my series of posts examining experiences with altered states of consciousness. This month I visited a float tank, what would have at one point been called a “sensory deprivation chamber” or an “isolation tank,” but now days they are called by more soothing sounding names such as R.E.S.T. [for “restricted environmental sensory therapy”] chamber. I like “flotation tank” because it’s the most neutral term, but it doesn’t necessarily convey what this technology does — which is to place one in body temperature water loaded with Epsom salt (increasing buoyancy) and cut out as much light and sound as possible by enclosing one in an insulated pod.
[Before I proceed, those interested in reading the first installment of this series, describing my experience with psilocybin mushroom tea — and which lays out my plan for the year — can find that post here.]
Withdrawing from sensory stimulation has a long history here in India. In yoga, it’s called pratyahara, and it’s one of the eight limbs of yoga described by Patanjali in his Yoga Sutras that date back to around 400 CE (that’s AD for the old school.) Of course, back in the day pratyahara was practiced in a cave or other isolated spot that cut one off from light, heat / cold, and sound as much as possible.
However, the technological approach is quite new in India. I visited 1000 Petals in Bangalore, which — as far as I know — is the first commercial float tank in India, and is — excepting the one at the company’s newer Mumbai (Bombay) location — among the only commercial tanks in the country as of now. [By “commercial” tanks, I mean only those that customers from the general public may visit. Who knows how may private tanks exist among India’s spice, coffee, and industrial barons? However, it’s an expensive piece of hardware for a private individual to own and maintain.]
I wasn’t sure what to expect, but had some basis for guesses. The general expectation is that with less stimulation, the brain both dials up awareness of the limited available input and may even start to create false signals. I’ve had experiences during meditation with under-stimulated sensory systems “acting up” in the face of reduced input — though this has primarily been during extended sessions of meditation. During the Vipassana 10-day meditation course, I frequently had morphing shapes play out scenes on the inside of my eyelids — purple on a black background — and on occasion heard vivid music in my head (but which I knew was solely in my head.) Also, on a number of occasions during the Vipassana course, I had sensations that my body was stretching toward the ceiling. I once even had an intense flowery scent that I’m not sure was an olfactory hallucination or a combination of the wind blowing just right to bring pollen into the meditation hall and my sensory attentiveness being dialed up to eleven due to under-stimulation. With possible exception of the flower smell, I never had any experience that would meet the common conception of a hallucination — i.e. sensory experience that I couldn’t tell whether was real or false. [Except in as much as I have only a vague notion of what being “real” means. An approximation suitable to getting through life in polite society.]
The question of the moment is whether the experience matched or defied my expectations? The general answer is, “both, in some measure.” Where it matched my expectations was in the fact that it was extremely relaxing. I spent much of the hour in a hypnogogic state (the state on the edge between wakefulness and sleep) and came out of the tank in the comfortably numb state that I associate with a good massage. Unlike meditation, where one starts to have back aches and leg pains that detract from comfort, keep one awake, and eventually cause endorphins to surge through one’s system, the flotation tank makes one as comfortable as one can be from the outset. This doesn’t mean that the tank cuts one off from all tactile sensation. Just because the temperature matches one’s body and one is floating so as to not be in contact with anything but salty water, doesn’t mean one becomes completely numb. Sensations do arise, and, even though they might be so subtle that they ordinarily wouldn’t draw one’s attention, one becomes aware of them because one’s mind is so yearning for input.
The biggest way in which the flotation tank defied my expectation was the utter lack of response to the dearth of visual signal. At one point I realized I could get a little of that purple on black shape-shifting that I experienced in Vipassana, but only if I consciously turned my attention to the underside of my eyelids. It didn’t force its way to the center of my attention like it had during Vipassana. There are several factors I can imagine playing into this disparity. For one, the float tank session was just one hour, where as the Vipassana course days lasted about ten hours on the mat. For another, the float tank was pitch black or as near to it as my eyes were capable of discriminating, whereas the mediation hall had windows and was merely dim. A more personal possibility is that, having done a lot of meditation in the intervening time, my mind isn’t as distressed by a lack of sensory input as it once was.
I can’t say that my mind didn’t respond to the lack of sensory stimulation at all. It just didn’t seem to respond to the lack of visual input. I didn’t opt to wear ear plugs (which were available,) but the water went into my ears and — except for some initial sensation while settling in — there was very little to be heard. Mostly, I could hear my own breathing and occasionally hear / feel my pulse. [I found I could dully hear external sounds in the bass range such as construction workers pounding or a helicopter flying over, but not at a level that was distracting, and my mind didn’t do anything with these stray sounds.]
As there was no smell to speak of and I could only taste the inside of my mouth if I turned my attention to it, this left tactile sensation as my primary source of stimulation. It’s funny, there is little to feel it would seem, but because one’s nervous system dials into what’s there, it begins to feel like one is laying in a perfectly form-fitting solid rather than on a liquid. And I became acutely aware of any sensations that came along. I didn’t have any strange “Alice-in-Wonderland Syndrome-eque” sensations like stretching or melting that I’ve experienced to a limited degree in meditation (possibly because those experiences may have resulted from an endorphin dump.) I did have a couple instances of leg twitch in the hypnogogic state, and I couldn’t feel the twitch at all because the leg wasn’t against anything solid, but I knew it happened from the ripples lapping up against my torso.
So, long story short, my mind didn’t behave strangely when subjected to an hour of sensory reduction. It was very relaxing and brought about an extended hypnogogic state — oddly without the imagery that I usually associate with that state.
Looking ahead: Next month, I’m going to be in the more familiar territory of meditation. However, I’ll be looking to see if ramping up the intensity of my practice to at least one hour every single day, produces any interesting outcomes. In April, I’ll be attending an introductory level workshop of the Institute for Clinical Hypnosis and Related Sciences (ICHARS) to learn how to extend my familiarity with hypnotic trance induction from self-hypnosis to working with others.