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Nitrogen Narcosis Uncovered

December 11, 2019

By Scuba Legends



Nitrogen Narcosis, a word we hear constantly in the conversations of divers. It seems to be the source of many funny underwater stories and others not so fun. Like many of the things in diving, there are as many theories as there are divers in the world. But, what exactly is Nitrogen Narcosis? How does it affect us? Is it dangerous?

What is Nitrogen Narcosis?

Nitrogen Narcosis is a phenomenon linked to increased pressure. It is defined as: “a reversible alteration of the state of consciousness of an individual in deep diving with compressed air”. Sounds a bit confusing, right?

Nitrogen Narcosis is somehow like being tipsy but underwater. Comparing to alcohol, being drunk can be funny or extremely dangerous. We all have friends who turn very funny when they drink and others who react in a negative way. In turn, a diver can be very funny underwater or can pose a great danger to himself and others.

The reason why the Narcosis occurs is still a subject of discussion among scientists. The most accepted theory is that communication between the neurons in our brain, which is based on nitrogen bridges, is disturbed. As you know, while diving we accumulate Nitrogen in our body. One of the places where Nitrogen accumulates are the mentioned communication bridges, which increases the distance between the neurons. The longer the distance, the more time they need to communicate.

Communication between the neurons in our brain is based on nitrogen bridges.While diving Nitrogen accumulates in the communication bridges, which increases the distance between the neurons. The longer the distance, the more time they need to communicate.

Nitrogen Narcosis Begins At Shallow Depths

Most of the divers are very happy after a dive. We simply associate it with the excitement of exploring the underwater world. There exist countless reasons why divers love spending their time below the surface. But there may be one more reason to explain that post-immersion emotion, Narcosis.

Narcosis is generally associated with a phenomenon related to depth, at 30m (100ft). Many divers are not aware that the symptoms of Nitrogen Narcosis appear in shallow depths, at 2m (6ft).  Although is true that the symptoms are not important until reaching the 30 metres (100ft), practically we are under the effects of Nitrogen Narcosis during the whole dive. The symptoms at shallow waters are little deterioration of reasoning and light euphoria. For an experienced diver these symptoms are barely noticeable. But they should be considered very seriously when diving with novice divers or with students. This could explain some difficulties in the apprenticeship and some typical attitudes of novice divers.

Scientists explain that you can not stop feeling the Narcosis through experience. No matter how many times you suffer it, you will always be narced. We would not be so daring to argue with the experts, so we will state that over time your body learns to tolerate and minimize those effects. The more you dive, the less you feel it.


Many divers are not aware that the symptoms of Nitrogen Narcosis can also appear shallow depths. Practically we are under the effects of Nitrogen Narcosis during the whole dive.


How does Nitrogen Narcosis affect us?

Even though we learn that narcosis begins from 30m(100ft), this is not so with all divers. Each diver is different and not everyone is narced once past 30m (100ft). As with alcohol, some divers are affected before, others later, in different ways and intensities. It depends mainly on the physiology of each diver. But no one escapes narcosis once crossed the border of 40m(130ft). That is one of the reasons why the maximum depth established for recreational diving is 40 metres (130 ft) in most countries.

It all starts with a small tingling in the stomach. It’s like a little euphoria. A feeling that does not look anything abnormal, just a small euphoria. Little by little, that euphoria moves from the stomach to the brain. Suddenly, a small fish makes you feel as if you were facing the best encounter of your live. A sandy bottom seems the most beautiful scenery you have ever seen. You are happy. It’s the best dive you’ve ever dived!

From that moment, everything can take different colors. You forget to check your air gauge or on the contrary, you look at it obsessively. It seems fun and safe to release the regulator and take out the tongue to your partner. When, late, you discover that you can not breathe without regulator, you realize that it is hanging on your back, you struggle recovering it because you are narced, thus it is not fun and safe anymore. It can happen too that you experience a terrible fear and decide to end the immersion. The variables of what can happen are very numerous and personal.

Symptoms less 30 meters

-Little deterioration of reasoning
-Light euphoria

Symptoms deeper than 30 meters

-Delayed response to visual and auditory stimuli.
-Alteration of reasoning and immediate memory.
-Errors of calculation and alteration in the capacity of decision making.
-Fixed ideas.
-Excess of trust and sense of well-being.

The Pro’s

Despite all these negative aspects, there are parts that we can see as positive. Those are the ones that divers use to deal with Narcosis. While diving, it is important to be clear about these aspects thereby we can take the right decisions.

– It does not get worse

Do not think that the more time you spend deep, the more narced you get. Once you are narced you are at your maximum level. And remember that this happens after a few minutes of crossing the line of 30m (100ft).

– Once you return to shllower waters of approx. 30m the effects disappear immediately

This is the main solution we teach in the courses. As far as solving the Narcosis refers, it is the only one. Point to your partner and ascend slowly until you reach a shallower depth of 30m (100ft), you will see that you immediately clear your head.

– No long-term damage

You will not find any side effects or damages once you finish your immersion. Remember that Narcosis is a phenomenon linked to deep diving with pressurized air. In other words,  it is like getting drunk but without hangover.

From this very moment you have to accept a fact: you will be narced. So your only options will be either to ascend to shallower waters to make it disappear, or learn to deal with Narcosis.

How to handle Nitrogen Narcosis?

From this very moment you have to accept a fact: you will be narced. So your only options will be either to ascend to shallower waters to make it disappear, or learn to deal with Narcosis. Here we bring you some tips:

– Gain expierence

Sometimes it seems that we use experience as advice for everything. For buoyancy, for Nitrogen Narcosis, etc. But there is no other truth than this, the more you dive, the better you will deal with any aspect underwater.

– (Re-)Practice your skills

There are some skills such as out of air that you may have forgotten over time. Paradoxically, your experience makes you forget those skills  that you learned in your Open Water Course. So it’s time to go back to the bases. Practice them  in shallow water over and over again until they become instinctive. Thus, in case of emergency and being narced, you will be able to realize them without need of thinking.

– Agree on buddy checks

Here is an example of what I do: I agree with my partner certain levels of depth in which we will stop and face each other. At this point we will count up to five with the fingers beginning with the index. Thus, it is very easy to identify if your partner is narced in case he forgets to stop, counts disorderly or suspiciously slow, and the other way around if its you who fail.

– Get training

Take the Advanced Course or the Deep Diver course. You have to see it that way. With training you will learn a lot. But in turn you will be accompanied by a professional who is very accustomed to dealing with narcosis. It’s a bit like partying and your instructor is the friend who does not drink to be able to drive. Enjoy your narcosis and let your instructor watch over you!

– Don’t dive overweighted

Something that terrifies me is to see divers who overweight themselves too much. But when we talk about deep diving I panic. When we dive deep it is very important to be calm and to avoid any over effort that makes us breathe heavily. In deep diving going overweight is dangerous and the reason for many accidents. Read The Bad Habit of Overweighting.

– Practice your buoyancy

It is important that you are able to maintain a slow breathing together with slow movements. You have to dive in the calmest way possible. If you are calm, everything will be less stressful. You can take better decisions when  narced. You will never be able to achieve this if your buoyancy is a disaster. So it’s time to become a buoyancy master. How? Easy, follow our Buoyancy Sessions.

Don’t be afraid!

There is no reason to be afraid of Nitrogen Narcosis and limit yourself because of fear. Most experienced divers love going deep. There must be a reason. You just have to do the  things the way they have to be done and keep the common sense. Follow the rules, be well trained, stay within your limits and be conscious about what you are doing. Do you want to go deep? Sign up for a Deep Diving Specialty Course and you will receive great training. Or start by doing the Advanced Open Water Course, get some experience and go step by step without pushing things.  Set your rhythms and enjoy every step you take. And remember that you can always decide not to go so deep and nothing happens. It is your decision and everyone must respect it

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