*OtterAquatics is reader-supported. When you purchase something through an outgoing link, we might earn a commission.

*OtterAquatics is reader-supported. When you purchase something through an outgoing link, we might earn an affiliate commission.

Nitrogen Narcosis: Why Does it Happen to Scuba Divers?

Table of Contents

Everyone that has taken a basic Scuba course should have learned about nitrogen narcosis.

Those that have taken the advanced surely will have learned about it and may even felt it. Depending on your instructor they may or may not have gone into depth on how it works.

Nitrogen narcosis is when a diver gets to a certain depth and a chemical reaction happens that causes the diver to act differently. This could be physiological like being confused poor judgment and a sense of euphoria. These are just a few symptoms that could arise. The cause of nitrogen narcosis is actually not known and still being researched.

This article is about nitrogen narcosis for recreational scuba and freediving. When tech diving, or freediving to great depth there is less science on how it works and more risk. So dive within your limits and use a dive computer at all times to stay safe.

What are the causes of nitrogen narcosis?

To be honest, experts are not exactly sure about the exact cause of nitrogen narcosis. But here is a brief overview of how we we think it works.

When going to any depth unless you are on a breath hold you inhale compressed air from a tank and your body will be under a lot of pressure from the water. This increases the pressure of oxygen and nitrogen in your blood.

At sea level, we normally breathe about 21 percent oxygen and 78 percent nitrogen, and the rest of it is Argon and other gases that have no real effect. As we go to depth the increased pressure affects your central nervous system. But scientists have not come to a specific mechanism that causes nitrogen narcosis to happen.

The physiological mechanisms that one may experience are also not fully understood. To make things more difficult the effects vary widely from person to person.

The main consensus is that it has to do with that the fat cells (lipids) which absorb nitrogen faster than other cells. This matters as the brain and the nervous system are highly composed of lipids.

This increase and uptake of excess nitrogen from lipids in tissues could cause swelling in the cells’ membranes, which in theory could cause them to malfunction.

What are Possible Symptoms of Nitrogen Narcosis?

These are some of the most common symptoms that one may have if they experience narcosis. For example, I have dived to over 50 meters in both Scuba and freediving and have never felt symptoms., everyone will vary. In most reported cases divers say that nitrogen narcosis feels like they’re uncomfortably drunk or dazed/ confused. This is visible to those around them as well. Common symptoms of nitrogen narcosis include but are not limited to:

  • Lack of judgment
  • Having trouble concentrating
  • Short-term memory loss
  • Sense of euphoria
  • Being disoriented
  • Reduced muscle function
  • Confusion
  • In severe cases hallucination
woman scuba diver posing underwater

Does Depth affect the Severness of Narcosis?

I know people that are been “hit” by nitrogen narcosis at 30 ft (10 meters) Below are some common symptoms that people have reported at specific depths. This is all anecdotal and just based on what other divers have reported.

  • 0-33(0-10M): Nothing
  • 33 to 100ft (10-30M)- Slight euphoria possibly some confusion
  • 100 to 166f (30m to 50M)- Slowed responses and response time, anxiety, and fearlessness.
  • 166+:Confusion, having trouble concentrating, loss of memory, super sensitivity, dizziness, euphoria, depression, and in the worst case unconsciousness.

“The Rapture of the Deep”

Narcosis has often been called the “rapture of the deep” and divers like to compare the narcosis to a feeling of pleasant drunkenness (some love getting to that certain depth. The “Martini Rule” is something some divers use to estimate the effects of narcosis during a dive.

It will depend on who you speak to but the “Martini Rule” is that for every 30 or 60FT (10-20M) of depth, a diver experiences the narcotic effect of drinking one martini. This is all hearsay and by no means should be followed.

It goes by many other names and here are some of my favorite.

  • Narced
  • Narked
  • Rapture of the deep
  • The martini effect
  • Inert gas narcosis

Are some people more prone to nitrogen narcosis?

Nitrogen narcosis can affect anyone and everyone even experienced divers that have never had any issues.

The risk of this happening is higher to get nitrogen narcosis if you:

  • Are diving multiple times a day
  • Drink alcohol or do drugs before diving
  • Are very stressed
  • Have been tired and fatigued
  • Are cold before and during your dive
  • Slept a little to not at all the night before

So if you are planning to do deep dives make sure to be relaxed, well rested, hydrated, and have the proper gear for the temperature.

When Does Narcosis Usually Occur?

Nitrogen narcosis often happens during the middle of your deep dive. So this is why you need to always be in contact with your dive buddy and know how they dive. Be aware of the conditions of the area and have a good briefing beforehand if you have never dove with this person before. If it does happen during the dive, calm the diver, ascend slowly, and do your safety stop as long as it is safe before getting on the boat.

How do you treat Nitrogen Narcosis?

The main treatment for nitrogen narcosis is to get out of the water and breath pure O2 if available. If the symptoms are not severe you can do a longer saftey stop at a shallow depth with your dive buddy to get out all of the nitrogen.

Be wary of this for future dives and you may need to use different mixtures of gases to combat these issues. Doing this though could increase your chances of getting decompression sickness (aka the bend). So speak to a doctor and a dicing professional to figure out what will work best for you.

Does it Cause Long-Term Issues?

Nitrogen Narcosis is not uncommon and rarely has long-term side effects but you should consult a professional if it happens to you. You will want to get emergency treatment if you experience any of the following symptoms after coming back to the water’s surface and it does not sort itself out.

  • Severe headache
  • General malaise
  • Tendon, joint, or muscle pain
  • Swelling of Joints
  • Dizziness
  • Chest pain
  • Having trouble breathing
  • Seeing double
  • Difficulty speaking

Is Nitrogen Narcosis Same as the Bends?

Nitrogen narcosis and the bends are sometimes confused with each other. They are very different but could overlap in some cases as both arise from the involvement of nitrogen in scuba diving.

  • Welcome

    My name’s Austin Tuwiner, a PADI Divemaster based in South Florida. With nearly 10 years of diving under my belt, I’ve accumulated the knowledge to help readers become better divers, buy their next piece of gear, and plan their dream dive vacation!

  • Join Our Facebook Group

    Feel free to ask any questions about scuba diving, liveaboards, freediving, and more, and the community (and me) will do our best to help you out.
    Join Here

  • Related Posts

    Leave a Reply

    Your email address will not be published. Required fields are marked *