What is Nitrogen Narcosis

Samuel Blake
Written by Samuel Blake

When I did my advanced dive license, during our second deep dive we got ‘narced’ as the instructor called it. He wanted us to feel the effects of nitrogen narcosis and test our reaction times and if we could still make sense of things down below. It was a pretty fun experience but it’s easy to see how it can turn dangerous.

What is Nitrogen Narcosis

The correct term for Nitrogen Narcosis is inert gas narcosis. It is a condition that many deep divers experience starting from 100 feet (30m) of water.

Nitrous oxide is a general anaesthetic and while no one knows for sure what causes nitrogen narcosis  in scuba divers, they believe it is the same process.

It is believed that many breathable gases react with the body tissues in particular the lipid tissues differently. As the brain is mainly comprised of lipid tissue the altered state of consciousness is felt here. Many gases exhibit anaesthetic effects at high pressures.

What Nitrogen Narcosis Feels Like

If we go back in time, scuba divers were once taught amongst all the other diving laws- ‘martini’s law’.

The law states that for every 50feet (15m) of depth the human body reacts as though it has consumed one martini without eating. This means for 100feet (30m) of water the body reacts as though it has consumed two martinis.

For some people the effect will be more and others less. But as you can imagine pairing alcohol with any type of sporting activity is a recipe for disaster. This law was eventually removed from training manuals as the light heartedness was taken too literally. Divers thought that if they could drink four martinis then they could indeed dive to 200feet (60meters).

So what does it really feel like? For me, I didn’t get as ‘narced’ as my dive buddies but I did feel the effects. My thoughts were slowed severely, everything felt like it was slow motion almost like being in a dream. As you can imagine slightly loosing your mind and mental abilities when 100 feet (30m) below the surface, many things can go wrong. Simply forgetting to look at your air gauge or dive computer can have severe consequences.

Have you ever been ‘narced’/ felt the effects of nitrogen narcosis. Let me know your stories in the comments!

Nitrogen Narcosis Symptoms

There are plenty of symptoms of Nitrogen Narcosis and it’s important to always dive with a buddy at depth. You may not even notice you are ‘narced’ so a buddy can potentially save your life. Symptoms include”

  • Feeling dizzy
  • Lightheadedness
  • Elation
  • Euphoria
  • Anxiety

It is a good idea to become very familiar with the effects of nitrogen narcosis if you are diving at depth. NEVER go deep diving alone, it could be fatal.

The Depth Divers Feel The Effects of Nitrogen Narcosis

The average depth one can expect to experience narcosis is 100 feet (30m) of seawater. The saying goes 100 percent at 100 feet meaning you’ll be narced at this depth.

If you descend to 140 feet or beyond you will experience significant narcosis. I must say here that 140 feet is the recreational diving depth limit so pushing that is strongly discouraged. Training organizations do not encourage it.

For people diving beyond that deep air training is required. Some can dive up to 160-190 feet on air but once past 200feet it’s likely you’ll feel the effects of very debilitating narcosis and possibly become unconscious.

Nitrogen Narcosis Treatment

Thankfully nitrogen narcosis is reversible simply be ascending, inflate your BCD slightly and begin to slowly rise. As soon as you ascend to a shallower depth the effects will subside. At this stage there are no known long term effects of nitrogen narcosis.

The hardest part of narcosis is that the affected diver may not have even noticed they were affected. If you are experiencing euphoria then it’s likely you won’t even realise the cause and continue as you are. This is why it is always important to know your limits and have a good dive buddy especially for deep dives.

If you have noticed your dive buddy is acting strangely then firstly ascend slightly to a shallower depth and see if their behaviour changes.

A quick Nitrogen Narcosis summary:

Bottom Line

Nitrogen narcosis is a reversible affect that occurs in divers at depths of 100 feet (30m) or deeper. Symptoms include lightheadedness, elation, euphoria and/or anxiety so if you notice yourself feeling different or your dive buddy be sure to rise until the effects have passed. There are no known long term effects of nitrogen narcosis but if don’t recognise the symptoms while diving it could potentially be fatal. Always dive with a buddy and know your limits.

About the author

Samuel Blake

Samuel Blake

My name is Samuel Blake. I am the founder of this scuba blog. I have been a diver for over 5 years. I care about helping you choose and decide on the best diving products.

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