1.
narcosis -- (unconsciousness induced by narcotics or anesthesia)
2.
nitrogen narcosis -- (confused or stuporous state caused by high levels of dissolved nitrogen in the blood; "deep-sea divers can suffer nitrogen narcosis from breathing air under high pressure")
Depressed mental state from high nitrogen pressure; usually does not begin to manifest on compressed air until below 25m. The narcotic effect nitrogen has at increased pressure. A condition suffered by fish when taken suddenly from deep water to the surface, causing expanding gases by rapid decompression.
Nitrogen narcosis or inert gas narcosis is a reversible alteration in consciousness producing a state similar to alcohol intoxication in SCUBA divers at depths beyond 30m. (Technically, it occurs at any depth, but in most cases doesn't become noticeable until deeper depths. A good analogy is one with alcohol... the effect of one martini per 10m) Jacques Cousteau famously described it as the "rapture of the deep". Its precise mechanism is not well understood, but it appears to be a direct effect of high nitrogen pressure on nerve transmission. While it was first observed with nitrogen (in air), other gases including argon and hydrogen also cause very similar effects under high enough pressure. Xenon is actually a usable anesthetic at atmospheric pressure, though it is too expensive to be used in practice.
The onset is hard to recognize, its severity is unpredictable,
and it can kill, from its own toxic effect or due to the resulting illogical behavior. However the cure for nitrogen narcosis is a simple one, as effects disappear upon ascending to shallower waters.
