Editing Nitrogen narcosis (section)

== Signs and symptoms ==
[[File:Console-narc.jpg|thumb|alt=The central area shows an LCD display clearly, but it becomes increasingly grayed out away from the centre |Narcosis can produce tunnel vision, making it difficult to read multiple gauges.]]
Due to its perception-altering effects, the onset of narcosis may be hard to recognize.{{sfnp|Bennett|Rostain|2003|p=301}}{{sfnp|U.S. Navy Diving Manual|2008|loc=vol.&nbsp;1, ch.&nbsp;3, p.&nbsp;40}} At its most benign, narcosis results in relief of anxiety&nbsp;– a feeling of tranquillity and mastery of the environment. These effects are essentially identical to various concentrations of nitrous oxide. They also resemble (though not as closely) the effects of alcohol and the familiar [[benzodiazepine]] drugs such as [[diazepam]] and [[alprazolam]].{{r |Hobbs2008}} Such effects are not harmful unless they cause some immediate danger to go unrecognized and unaddressed. Once stabilized, the effects generally remain the same at a given depth, only worsening if the diver ventures deeper.{{sfnp|Lippmann|Mitchell|2005|p=103}}

The most dangerous aspects of narcosis are the impairment of judgement, multi-tasking and coordination, and the loss of decision-making ability and focus. Other effects include [[vertigo (medical)|vertigo]] and visual or auditory disturbances. The [[syndrome]] may cause exhilaration, giddiness, extreme anxiety, depression, or [[paranoia]], depending on the individual diver and the diver's medical or personal history. When more serious, the diver may feel overconfident, disregarding normal safe diving practices.{{sfnp|Lippmann|Mitchell|2005|p=105}} Slowed mental activity, as indicated by increased reaction time and increased errors in cognitive function, are effects which increase the risk of a diver mismanaging an incident.{{r |Doolette 2008}} Narcosis reduces both the perception of cold discomfort and shivering and thereby affects the production of body heat and consequently allows a faster drop in the core temperature in cold water, with reduced awareness of the developing problem.{{r |Doolette 2008 |Mekjavic et al 1994 |Mekjavic et al 1995}}

The relation of depth to narcosis is sometimes informally known as "Martini's law", the idea that narcosis results in the feeling of one [[Martini (cocktail)|martini]] for every {{convert|10|m|ft|abbr=on}} below {{convert|20|m|ft|abbr=on}} depth. This is a rough guide to give new divers a comparison with a situation they may be more familiar with.{{r |Brylske2006}}

Reported signs and symptoms are summarized against typical depths in meters and feet of sea water in the following table, closely adapted from ''Deeper into Diving'' by Lippman and Mitchell:{{sfnp|Lippmann|Mitchell|2005|p=105}}

{| class="wikitable" style="margin: 1em auto 1em auto; text-align:center;"
|+ Signs and symptoms of narcosis, breathing air
! scope="col" | Pressure (bar)
! scope="col" | Depth (m)
! scope="col" | Depth (ft)
! scope="col" | Comments
|-
| 1–2 || 0–10 || 0–33 || {{unbulleted list | Unnoticeable minor symptoms, or no symptoms at all}}
|-
| 2–4 || 10–30 || 33–100 || {{unbulleted list | Mild [[wikt:impairment|impairment]] of performance of unpracticed tasks | Mildly impaired reasoning | Mild [[Euphoria (emotion)|euphoria]] possible}}
|-
| 4–6 || 30–50 || 100–165 || {{unbulleted list | Delayed response to visual and auditory stimuli | Reasoning and immediate memory affected more than motor coordination | Calculation errors and wrong choices | Idea fixation | Over-confidence and sense of well-being | Laughter and [[wikt:loquacity|loquacity]] (in [[Hyperbaric chamber|chambers]]) which may be overcome by self-control | Anxiety (common in cold murky water)}}
|-
| 6–8 || 50–70 || 165–230 || {{unbulleted list | Sleepiness, impaired judgment, confusion | [[Hallucinations]] | Severe delay in response to signals, instructions and other stimuli | Occasional dizziness | Uncontrolled laughter, [[hysteria]] (in chamber) | Terror in some}}
|-
| 8–10 || 70–90 || 230–300 || {{unbulleted list | Poor concentration and mental confusion | [[wikt:stupefaction|Stupefaction]] with some decrease in [[dexterity]] and judgment | Loss of memory, increased excitability}}
|-
| 10+ || 90+ || 300+ || {{unbulleted list | Intense hallucinations | Increased intensity of vision and hearing | Auditory hallucinations (the wah-wahs) <ref>{{cite magazine |url=https://indepthmag.com/the-call-of-the-wah-wah/ |title=The Call of the Wah-Wah |magazine=InDepth |access-date=15 August 2024 |archive-date=15 August 2024 |archive-url=https://web.archive.org/web/20240815183620/https://indepthmag.com/the-call-of-the-wah-wah/ |url-status=live }}</ref> |Sense of impending blackout or of [[Levitation (physics)|levitation]] | Dizziness, euphoria, [[Mania|manic]] or [[Depression (mood)|depressive]] states | Disorganization of the sense of time, changes in facial appearance | Unconsciousness, (approximate inspired partial pressure of nitrogen for anaesthesia is 33&nbsp;atm){{r |Doolette 2008}} | Death}}
|}