Over the weekend I had my first experience in an isolation tank. I like exploring my own consciousness and I'm willing to try just about anything once, so it seemed like a logical thing to do. I had heard that experts recommend no more than one hour for first-timers, but I wanted to make sure I felt the full impact (whatever it might be) and so I opted for two hours. It wasn't total sensory deprivation, but it was very close. The water was the same temperature as my skin and had epsom salt to make floating effortless, the tank was almost pitch black, and I wore earplugs to block out any sound. I was intermittently aware of my breathing and could occasionally sense my heart beating, but other than that there were really no external sensations reaching my brain.

I didn't know quite what to expect. Not being under the influence of psychedelic drugs and not planning to spend 20 or 30 hours in the tank, I wasn't expecting a visit from the Earth Coincidence Control Office. But I was optimistic that I would learn something about the relationship between sensory information and consciousness. I thought it would probably help me to cleanse the doors of perception, and figured I had an outside chance of feeling the sensation of an out-of-body experience.

Overall, the time in the tank was somewhat disappointing. I thought that in the absence of any external stimuli my mind might start manufacturing auditory or visual hallucinations, but it didn't. For the most part, it was as dark in my mind as it was in the room. I was self-aware for most of the two hours but my mind still felt localized in the place where my head was. After the first ten or fifteen minutes of thinking random thoughts as I do in everyday life, my mind became very quiet and I was able to avoid thinking of anything in particular. Thoughts did periodically enter my mind unbidden, but I was able to observe them passively and non-judgmentally, as Vipassana meditation recommends, and they quickly faded away, as if they knew their attempts to command my attention would be futile.

Time did get a little distorted. When the two hours were over I felt like it had been about an hour and a quarter. I'm very confident that I didn't fall asleep at all, but in such a state it's difficult to claim anything with certainty. I'm fairly good at judging the passage of time in ordinary life, so my incorrect guess about the passage of time was somewhat surprising, but the discrepancy wasn't so great as to be startling, and it seems reasonable that in the absence of anything occurring, the mind wouldn't be very good at judging how quickly time was passing.

As I said, my experience in the tank was somewhat disappointing. But once I emerged, I discovered that my mind had indeed been altered from the experience. I was initially tempted to describe the change as merely a recalibration: after two hours of not getting any sensory input, I figured my brain had simply turned the knobs up. But there was more to it than that. The differences weren't just quantitative, but also qualitative. It wasn't just that I perceived the light as brighter and the sounds as louder. Colors were more colorful, and sounds were, for lack of a better word, soundier. On the way home, the breeze on my skin felt breezier. Space felt as if it had more depth... not that it was more than three-dimensional, but rather that I was realizing that in ordinary everyday life it was a little less than three-dimensional.

I especially noticed a change in music. The songs on the radio seemed more... songy. When I got home I played my guitar, and felt a desire to play slowly, at about half speed, in order to give each note a chance to exist in the fullness of time, knowing that the purpose of playing the song was to play it and not to have played it. ("It's the journey, not the destination"... "Be Here Now"... etc). Then I played some of my favorite songs on my ipod. My ipod is filled with two (partially overlapping) types of songs: songs I like because they demonstrate artistry, and songs I like because they move me emotionally. I felt a desire to listen to songs only in the latter category. And they sounded even better than usual.

My other senses were heightened as well. I washed a bowl of blueberries in cold water and the water felt... I'm not sure what word to use here... waterrific? I put a little splenda on them and ate them one by one, which at the time seemed to be the only proper way to eat them. Not surprisingly, they tasted great.

In addition to the overall vividness of my senses, I also had a general sense of well-being and connectedness with the world - benevolence, compassion, sympathetic joy, and equanimity (which you might recognize as the four sublime virtues of Buddhism). I know that in some ways the description I've given sounds a lot like a drug high (maybe something like a mescaline trip, only to a far lesser degree). But it didn't feel like a drug high, and my cognitive functioning was enhanced rather than impaired. I don't want to overstate the magnitude of the changes. My natural state is to feel a little like this all the time, and this experience maybe moved me from a 1 to a 2 on the Buddhaometer. It was nowhere near nirvana, or even the feeling one would get from an empathogen like MDMA.

Alas, the change was only temporary. Several hours later I was no longer able to tell if it was having any impact at all, and by the next morning I was pretty sure that I was back to my pre-tank state. The next day, I wondered which mental state was the "correct" one: my ordinary state, in which my mind is bombarded by thousands of external stimuli and is constantly in overdrive, or my post-tank state, which required the equally unnatural condition of total sensory deprivation to achieve. Of course, even if I decided that my post-tank mental state were "correct" and desirable, I may not have the ability to consciously choose to make that my default mental state.

All in all, the experience wasn't life-changing, and I don't think it revealed some previously hidden truth about the nature of reality, but I'm glad I did it once. I am not specifically recommending that you try it, or that you don't try it, although my advocacy of the "try almost anything once" policy does seem to prescribe giving it a shot. Keep in mind, your mileage may vary.