We have all heard the stories of divers doing crazy things, even lethal ones, under the influence of nitrogen narcosis. If you are a deep diver, you have likely been “narked” at least to some degree. However, you may not have been aware of it. We have been taught that the effects of nitrogen narcosis will show itself at depths, with 100 feet 30 meters being the most frequently quoted depth. However, our body will start having an effect long before we notice it. Additionally, we may never really notice it in ourselves and our dive buddy may not notice the changes. In the article “Going Deep Whilst Scuba Diving”, I touched upon the subject of Nitrogen Narcoses, but the topic does deserve more insight.
The effects of inert gasses on the human body have been studied since the 1800s. French researcher Victor Junod was the first to describe it in 1834. Physician Walter Moxon suggested in 1881 that blood forced under pressure into parts of the body, where it normally did not flow, could cause emotional problems.
Diving physiologist Albert Behnke was the first to suggest that nitrogen was the cause in 1935. A few years later added helium as another gas that can cause the problem.
Jacques-Yves Cousteau recounted personal experiences involving a mysterious diver’s disease, which he termed l’ivresse des grandes profondeurs (“rapture of the deep”). He wrote,
“The chief symptom of this phenomenon is, to put it bluntly, the sensation of becoming as drunk as a hoot owl.”
Divers and dive agencies soon were talking about “Martini’s law”. The “law” held that the effect of every 50 feet (15 m) of depth was equal to drinking one martini. A list of symptoms is listed later.
Over the years, this “law” became less favored as too often divers were assuming their ability to handle alcohol related to their ability to resist nitrogen narcosis. From a medical viewpoint, nitrogen narcosis is more similar to an anesthetic effect than an alcohol one. Technically, the proper term is “Inert Gas Narcosis”. This is because any inert gas can create the impact. Still, recreational divers do not dive with these inert gas mixes so we will use the term “nitrogen narcosis”.
We learned that nitrogen narcosis effects divers at 100 feet/ 30 meters. That is not really true. That depth is where the effects become recognizable. Often a dive buddy will start noticing things before we do. Controlled studies by the US Navy in hyperbolic chambers has shown that some individuals are affected at 2 ATM which is 33 feet/10 meter. The same study showed that there is a measurable decrease in mental processes in all divers at the 3 ATM (66 feet/20 meters). It is unlikely, however, that the diver will notice the changes at this point. At 4 ATM (99 feet/30 meters) most divers are aware of some impairment. As we move deeper that the 4 ATM point, the impairments become more enhanced and the degrading of out mental processes increases more rapidly.
These control studies also show that an individual’s responses will vary day to day. Other “wet” studies have also shown that the diving conditions also play a role in the impact of being narked. Divers diving in cold water or poor visibility often shows signs of being narked sooner than they did in good conditions.
Studies have shown that certain actions both before and during the dive can influence the onset of nitrogen narcosis. Consider these items before your next dive.
- Become certified as a deep diver: A short study done in 1965 had three control groups each with no prior diving experience. Each group was told of nitrogen narcosis but given different facts. The first group was told that all divers are severely impacted at 130 feet. The second group was given basic facts but told that it seldom happened and the impact was mild when it did. The third group received a three-hour lecture on the topic reviewing all known research. This group was also told that will power could overcome the impacts. The results showed that the third group could go significantly deeper before becoming severely impacted. While the study was too small of a test to have solid conclusions it is enough to show that knowledge of nitrogen narcosis is important to limit/delay the impact. A deep dive course allows you to experience nitrogen narcosis with a trained instructor monitoring your reactions.
- Be Fit and Rested: A diver that is out of shape or tired is more likely to experience the effects. Also, a tired or unfit diver is also increasing the risk of DCS.
- Drug and alcohol-free: Alcohol and drugs in your system may make you more likely to feel the impact sooner. This includes legal and illegal drugs. Over-the-counter drugs used for cold and sinus reliever can also influence your ability to recognizes the onset of impairment. Having a hangover from the night before can complicate your bodies reactions.
- Beware of Carbon Dioxide: At one point it was believed that carbon dioxide was the cause of the narcosis. However, that has been disproved. It is believed that the presence of higher levels of carbon dioxide can accelerate the onset of narcosis. We can increase the level in our bodies when we overexert ourselves. Also if we do not fully exhale, we will breathe back in the air we exhaled that has higher amounts of carbon dioxide.
- Plan your dive, dive your plan: One of the impacts of being narked is losing our ability to multi-task. The better we plan our dive and sticking to it, the less we need to think about it. On deep dives, include in your plan a few mental checkpoints. Two minutes after arriving at depth, have an exchange with your dive buddy. The impact of being narked will generally appear within the first two minutes at a depth. A simple prearranged test should be good enough. You might also want to include a signal to ascend a couple of meters.
- Be self-aware: Remember the symptoms of nitrogen narcosis. Judge if you are experiencing any of them. If so are they at the point where they can cause you danger.
- Watch your buddy: Look for behavior that seems unusual. This is easier if you have been diving with the same dive buddy as you will know what is normal for them.
- KISS: The Keep It Simple Stupid rule, with a deep dive, you have limited time. So keep your dive plan simple and do not try to do accomplish too much.
- Check your gauges and computers: Seeing is believing. If your dive computer says it time to surface believe it. If your air pressure gauge says you are getting low on air believe it.
- When in doubt ascend: One good thing about nitrogen narcosis is that it impacts rapidly decreases when you ascent. If you think you are narked, ascent a couple of meters, wait two minutes and evaluate yourself.
Signs and Symptoms of Nitrogen Narcosis
DEPTH: 33-100 FEET (10-30 M)
- 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.
- 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.
- A 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
Being Narked Is Not All Bad
Becoming narked is going to happen if you go deep. Being aware of the impact it has on your abilities is the key issue. If you still seem in control and your dive buddy agrees then there is no reason why you cannot continue. But you do need to understand the limits.
On some of my deep dives, I have noticed slower thinking. That is not always the case. I was on one dive exploring a small aircraft wreck at 38 meters. My task was to locate the plane’s data plate. I knew where the plate was to be found and had a little scrub pad to remove any dirt that may have been covering it. Being a small cockpit my dive buddy watched me from outside the wreck but just a few meters away. I could not find the data plate. The last 15 seconds inside, I used my action cam to video where I was looking. When I reviewed the video later I could see a part of the data plate and even read some of the numbers.
One of my dive buddies also uses a rebreather. He mentioned that one of the things he noticed using the rebreather was that he thought much clearly beyond 100 feet.