Nitrogen Narcosis will effect every scuba diver at a certain depth even those who say they never get narced. Recreational divers in the 1970s and 1980s, while studying for their open water diver certification learned much about the laws that affected gas under pressure.
Just like the divers today, they learn how the laws of Boyle, Dalton, Charles, and Henry cause the body to react differently due to pressure. Back in the old days of scuba divers also learned what is known as “Martini’s Law.”
This “law” expressed that for every 50 feet (15 m) of depth, the body reaction was equal to drinking one martini before eating, and divers could easily forget what they are supposed to do and even become irrational.
The actual effect being taught was that of nitrogen narcosis. The description of Nitrogen Narcosis as “Martini’s Law” was the only thing lighthearted in those early training manuals.
“Martini’s Law” fell by the wayside as too many divers took the rule to literally, thinking if they could drink four martinis they could dive to 200 feet/ 60 meters.
Nitrogen narcosis can give similar symptoms as alcohol intoxication.
Today, the term Nitrogen Narcosis is still in use, but it also called Inert Gas Narcosis as it also can be caused by other gasses. As early as 1834, Victor Junod, a French scientist suggested that a high partial gas pressure could create a change in emotional states. In 1935, Albert Behnke was the first to tie the effect to nitrogen, and in 1939, he and others on his team expanded it to include helium.
In 1955, along with the release of his documentary, Jacques Cousteau's book, The Silent World gave the nonscientific world the first description of what he called "ivresse des grandes profondeurs" - "Rapture of the Deep."
In the book, The Silent World, Cousteau relates a story of his friend, Frederic Dumas in an attempt to see how deep he could go. Dumas was to dive as deep as he could in 240 feet of water. At his deepest the plan was to remove his weight belt and attach it to the measured line.
Here is how it turned out:
"The light does not change color as it usually does underneath a turbid surface. I cannot see clearly. Either the sun is going down quickly, or my eyes are weak. I reached the hundred foot knot. My body doesn't feel weak by I keep panting.
The damn rope doesn't hang straight. It slants off into yellow soup. It slants more and more. I'm anxious about that line, but I feel wonderful. I have a queer feeling of the beatitude. I am drunk and carefree. My ears buzz and my mouth taste bitter. The current staggers me as though I had too many drinks."
How do you get Nitrogen narcosis?
If you dive deeper than 60 feet/18 meters, you will get narced. Whether there is a noticeable effect, is a different story. When you do your deep dive in the advanced open water diver course, a few exercises are done to illustrate to you the effect that the depth has on your thinking and coordination.
You do a few simple test at the surface, again at around 60 feet/18 meters and 100 feet/ 30 meters. When you return to the surface, you may be surprised at the results as you may not have thought there was any difference in your performances.
That another trait this shares with intoxication, you might not notice. We know the symptoms of Nitrogen Narcosis (see list below for more details) and a general range of when they can happen. However, just like in DCI / Decompression Illness , it is not a cut and dry type of formula. The dive profile you did yesterday with no visible effect might make you have tunnel vision today.
You will hear divers say that the more frequent you dive deep, the less likely you will become effected. That is not true. However, it may seem true because the task has become easier as you become more experienced. Many websites will give you great advice on how to avoid becoming narced. Many of their suggestion apply to any dive, so they are not much of a help.
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There are a few things that we do know that contribute to the cause of narcosis:
While the alcohol you consumed the previous night may have burned off to an acceptable level, it will still be effecting the same conditions slightly as the narcosis. In other words, you already have a running start. Some over the counter medicines for things such as motion sickness can also effect the same nerves. Allow a full 8 hours for alcohol and medicines to leave your system before a deep dive.
Plan your dive with as few multitasks as possible. When we dive, we are always multitasking. We do the task we set out to as well as checking our gauges, checking our buddies, dealing with currents a seemly endless list. Divers tested in open water, and a chamber show less effect in a chamber. This has been related to the fact that the subject has less to focus on. So limit your underwater task on each dive.
Your mindset will play a major role. Clearing your mind and diving stress-free is said to hold off the effects. Practicing a dive in your mind before going down, can help you cope. It is fine to understand that you will be effected. However, your mind has a control on how strongly it will impair you.
Elevated levels of carbon dioxide also seem to have an impact. So give up the pre-dive cigarette. Overexertion can raise your CO2 levels as well, so limit your physical activities before a deep dive. Slow your descent so that you are not building CO2 on your way down.
- Studies have shown a dizziness in divers who descend fast and then level out rapidly at depth. Your regulator can also cause you to breathe hard, increasing the CO2 in your lungs, if it needs maintenance. Pause when you reach your depth. This may relate to the CO2 discussion. However, research has shown divers who pause a minute at depth to check gauges and equipment as well as survey their surrounds are less affected. Know your basic skills. Being able to react without thinking in an emergency is a part of reducing multitasking.
Unless it is causing you to do something that injures you or your buddy, Nitrogen Narcosis has no lingering effect.
The effects will go away when you ascend to the point that the effect started. Similar to being drunk, it is possible that you may forget what you did while under the effects.
Signs and Symptoms of Nitrogen Narcosis
DEPTH: 33-100 FEET (10-30 M) ( all on air)
- Mild impairment of performance of unpracticed tasks.
- Mildly impaired reasoning.
- Mild euphoria possible.
DEPTH: 100-165 FEET (30-50 M)
- Delayed response to visual and auditory stimuli.
- Reasoning and immediate memory affected more than motor coordination.
- Calculation errors and wrong choices.
- Idea fixation.
- Overconfidence and sense of well-being.
- Laughter and loquacity (in chambers), which may be overcome by self-control.
- Anxiety (common in cold, murky water).
DEPTH: 165-230 FEET (50-70 M)
- Sleepiness, impaired judgment, confusion.
- Severe delay in response to signals, instructions, and other stimuli.
- Occasional dizziness.
- Uncontrolled laughter, hysteria (in a chamber).
- Terror in some.
DEPTH: 230-300 FEET (70-90 M)
- Poor concentration and mental confusion.
- Stupefaction with some decrease in dexterity and judgment.
- Loss of memory, increased excitability.
DEPTH: 300-PLUS FEET (90-PLUS M)
- Increased intensity of vision and hearing.
- Sense of impending blackout, euphoria, dizziness, manic or depressive states, a sense of levitation, disorganization of the sense of time, changes in facial appearance.
Source: NOAA Diving Manual
Know your limits
While the most serious effects are outside of the recreational diver's range, it is still a concern with recreational divers. Even the effects at 60 feet could lead us to a bad decision.
The best we can do is to remember what can happen and monitor ourselves and our dive buddies for any signs of being narced If any appear, ascent a few meters and check again. Many times ascending just a few meters is enough to clear our heads.
When was the last time you got narced, and what happened? Let us know in the comments below.
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Article written by Rutger Thole who is an avid scuba diver and loves to travel, dive and write about scuba diving. Based in Amsterdam he runs bookyourdive.com and at least twice a year he plans a dive trip of the beaten track.