<Tr> <Td_colspan="2"> Divers breathe a mixture of oxygen, helium and nitrogen for deep dives to avoid the effects of narcosis . A cylinder label shows the maximum operating depth and mixture (oxygen / helium). </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> Narcosis while diving (also known as nitrogen narcosis, inert gas narcosis, raptures of the deep, Martini effect) is a reversible alteration in consciousness that occurs while diving at depth . It is caused by the anesthetic effect of certain gases at high pressure . The Greek word ναρκωσις (narcosis) is derived from narke, "temporary decline or loss of senses and movement, numbness", a term used by Homer and Hippocrates . Narcosis produces a state similar to drunkenness (alcohol intoxication), or nitrous oxide inhalation . It can occur during shallow dives, but does not usually become noticeable at depths less than 30 meters (100 ft). </P> <P> Except for helium and probably neon, all gases that can be breathed have a narcotic effect, although widely varying in degree . The effect is consistently greater for gases with a higher lipid solubility, and there is good evidence that the two properties are mechanistically related . As depth increases, the mental impairment may become hazardous . Divers can learn to cope with some of the effects of narcosis, but it is impossible to develop a tolerance . Narcosis affects all divers, although susceptibility varies widely from dive to dive, and between individuals . </P>

Alteration of consciousness during deep sea diving is known as