The effects of nitrogen on divers and nitrous oxide on land-dwellers are probably somewhat similar, and may be produced by similar mechanisms. The interesting thing is that the actual chemical events that lead to narcosis (or general anesthesia) are not understood, despite many years of research. We know what KINDS of gases are likely to produce sedation or anesthesia, and we can even build them, but we cannot really explain why they work.
Most people talk about narcosis as an either/or phenomenon: You are narced, or you are not. It is highly likely that what actually happens is that, from the moment you submerge, your nervous system is affected by nitrogen, and the effect increases as you go deeper. Where you become aware of the narcosis can vary, but most people will say it's at or below 100 fsw. The impairment can be manifested as euphoria (usually in good visibility and warm water) or as paranoia (more common in cold water and poor viz), and frequently involves a degree of tunnel vision (poor situational awareness) and poor judgment, clumsiness with physical skills, and even hallucinations when it is severe.
Bob said that narcosis isn't harmful, and that's true in the sense that it does no permanent harm we know of to the central nervous system. But people have died because of it, because they went too deep, or ran out of gas because they stopped checking gauges. It is not a funny thing, even when the experience is euphoric.
As Bob said, narcosis varies from individual to individual (just as susceptibility to alcohol and anesthetics does) and can also vary from day to day in the same individual. It's also important to know that carbon dioxide is an extremely narcotic gas, so breathing patterns that result in CO2 retention augment nitrogen narcosis, sometimes to a debilitating degree.
This is one of the reasons why new divers are advised to expand their envelope slowly, doing shallower dives until they are comfortable, before they head for the deeps.
Most people talk about narcosis as an either/or phenomenon: You are narced, or you are not. It is highly likely that what actually happens is that, from the moment you submerge, your nervous system is affected by nitrogen, and the effect increases as you go deeper. Where you become aware of the narcosis can vary, but most people will say it's at or below 100 fsw. The impairment can be manifested as euphoria (usually in good visibility and warm water) or as paranoia (more common in cold water and poor viz), and frequently involves a degree of tunnel vision (poor situational awareness) and poor judgment, clumsiness with physical skills, and even hallucinations when it is severe.
Bob said that narcosis isn't harmful, and that's true in the sense that it does no permanent harm we know of to the central nervous system. But people have died because of it, because they went too deep, or ran out of gas because they stopped checking gauges. It is not a funny thing, even when the experience is euphoric.
As Bob said, narcosis varies from individual to individual (just as susceptibility to alcohol and anesthetics does) and can also vary from day to day in the same individual. It's also important to know that carbon dioxide is an extremely narcotic gas, so breathing patterns that result in CO2 retention augment nitrogen narcosis, sometimes to a debilitating degree.
This is one of the reasons why new divers are advised to expand their envelope slowly, doing shallower dives until they are comfortable, before they head for the deeps.
