I am one who feels narcosis distinctly. But it varies, possibly depending on how much diving I have been doing. I can make an analogy to drinking: If I haven't had any alcohol in weeks, I distinctly feel a sensation with even that very first beer or glass of wine. But during periods when I've had, say, a couple of glasses of wine with dinner every night for a month, the effect of the day's first glass of beer or wine is almost unnoticeable. I'm mainly a vacation diver, and if it's been a while since I've been diving I start to perceive things as surreal or dulled as early as 80 or 90 feet, and it really picks up around 100 feet. Quite often during the first few days of week-long dive vacations I've had to signal to my dive buddy (wife) around 100 feet that I feel narced and am going to ascend a bit. But when I have the opportunity to dive regularly over an extended period, I become more tolerant. A few years ago when I had the opportunity to dive almost every day for over a month, the occasional dive that bottomed out at 130+ feet did not make me feel especially narced--at least I did not note that in my log, which I probably would have done. It seems that the more I dive, the more I grow tolerant of the narcosis and notice it less and less (though I am no doubt impaired), just as the more I drink the more I might grow tolerant of alcohol and notice less and less how impaired I am.
