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Narcosis when

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.


neoprene dreamer
Aug 22, 2001
I have heard of nitrogen narcois when talking about scuba diveing, but dosen't it hit you when freediveing as well? :blackeye
What are the signs of it and is there any danger?
When can one exept to get it, I mean at what depth?
Well thanks to all of you who have posted on this site, you have been such a resource of information:t

It is very possible to get narcosis while freediving.

Narcosis in constant weight will happen in the following conditions:
- Dives to more than 65m (> 70m if you are a scuba diver who is very used to narcosis)
- You must also be cold, in cold water
- The water must be very dark
- You have high CO2 (i.e. you didn't overventilate)

If all 4 of those are satisfied, you will almost certainly get narcosis during the early part of the ascent. If you dive more than 70m in cold dark water (and being cold), the narcosis will be very noticeable. More than 80m, the narcosis will be so severe that it is dangerous-- you can even forget to keep kicking. More than 85m, the narcosis is very dangerous. On very deep dives you can also get narcosis during the last part of the descent.

The signs or freediving narcosis are not the same as scuba narcosis, but similar. Everything seems 'wavy', everything sounds distant, you can't think clearly, you feel a buzzing all over your body, feeling 'drunk', can't concentrate on kicking, confusion, fuzzy vision, fear, dizziness.

In warm, clear water, there is almost no narcosis during constant weight. In warm clear water, I have heard that you must do a dive to 100+m on a sled to experience narcosis.

Eric Fattah
BC, Canada

thank you Eric, so it seems that I am not about to experience any of that dizziness.. bit sad it could be fun to get little "drunk" when diveing.. :duh
but thanks Eric once again.
Hey waitaminute.
I thought narcosis was all about nitrogen and caused by compressed air breathing? Do you mind if I ask where you heard about getting it on free dives? I have a hard time beleiving there's even enough time to experience it on a free dive.
Actually I think narcosis sounds kind of cool. Are you saying that the more you get it, the easier you get off?
Not an appropriate question...

Ok - my question is this...

Have you ever taken a dive class? It is taught that this isn't about breathing from a tank - this is about the concentration of nitrogen in your blood (Either while breathing from a tank or the available air in your lungs) and how your body reacts to it under pressure...

Getting narc'ed is also very dependent on your physical makeup, the amount of sleep you had, the temp of the water, etc.

Some people can get narc'ed at 60 feet, while others can dive much deeper and not feel it's effects.

Those who have responded are very knowledgable (ie; Eric Fattah) who have done much research on the physiological aspects of freediving.

Eric recently broke the longstanding Constant Ballast World Record of 81 metres / 266 feet - he experienced being narc'ed first hand during this record attempt. Read his account of what occured during that attempt on our site.

He is also a member of the Canadian Freediving Team that will be competing at the worlds in Ibiza in October.

I take his word for gospel on this topic.
No, I've never taken a dive class. I learned to dive by diving, then from guys who do it for a living--like lobster divers, fishermen, etc--and what I pick up from people I run into who seem to know what they are talking about. I've read dive training manuals apart from a few good tips, they seem completely wrong-headed and often contraproductive. (e.g. full of it)
The reason I registered for this forum is that it seemed like a good way to learn more. It's a great resource.
What I don't understand is your antagonism to AKING QUESTIONS??????? I don't understand how a question can be "inappropriate"--you either have that question in your mind or you don't. Have you ever heard the educator's expression, "The only foolish question is the one you don't ask"?
Frankly, I find it a little annoying to have you jump on my ass all the time just for trying to find things out (or for having a different opinion or attitude, but that's not as ignorant and rude as flaming for questions).
But I can handle people being jerks to me. What bothers me is that I'm about to roll out a website that is aimed at appealing to people just getting into diving, or convincing people that free diving is a better alternative to tanking. I have already listed this forum as a resource. I hate to think that anybody coming in here asking a question that you don't find "appropriate" will end up being told they have to take PADI classes to free dive or flamed for not knowing enough about something to ask a damn question about it.
Are you getting this?
Please forgive my irritation...

I am learning to accept the fact that not everyone has gone thru a tank diving class where they teach the basics on physiology and physics of diving...

Sorry... :(
Cliff, I have to agree with snorlkebum. You mentioned in another post how you got angry with people who hadn't done the research before asking the question. This forum IS the research, especially with freediving. I have learned more on this forum this year than I could imagine. I have had great leads to online gear,reviews,access to world class divers, access to world class training, places to dive, physiology, and even met some new dive buddies through this site(FD48, JMD, Tony G, Patrik D,Kirk Krack), and it has motivated me to compete for my country and meet even more people in this very small community.
IMHO, you have a responsibilty to the community (Deeperblue) that you have helped to create and establish. No other website comes close to it as far as I am concerned. I respect you and your opinions, and so does everybody else.
In my limited experience of being a teacher or leader, I have to constantly remind myself of 2 things.
1. At one time I knew nothing.
2. If everybody knew already, I wouldn't have to teach.

Sincerely and respectfully,
Erik Young
I stand corrected...

I realize that I was out of line this weekend - not quite sure where this venting was coming from, but I want to apologize to all whom I may have offended in the process.

I hadn't expected this to become such a resource for so many.

I am now much more aware of this and will try to temper my responses with wisdom and patience.
Narcosis & No-Limits

The question was:
'How do you avoid narcosis for no-limits (150m) dives?'

The answer is, you don't. In fact, I have talked to divers who have gone 100m+, and apparently, the narcosis & O2 toxicity are so bad that first you get tunnel vision, then your vision disappears completely, so you can't see anything.

In fact, Audrey Mestre blacked out from O2 toxicity during the ascent on a no-limits dive. Still attached to the float pulling her up, she 'woke' up some seconds later, still on the ascent, as the O2 pressure in her lungs dropped to more reasonable levels.

Scary place to wake up.

Eric Fattah
BC, Canada
It is a great resource and I think you guys should be proud of doing a major service to free divers. I hope a lot more people can access this in the future.

I think I got here by accident, I just typed all kinds of freediveing related addresses nad got here. since that I have used this like a library! great place where as it has turned out all the questions have been answered! thanks Cliff and all the people who have helped me with my questions, they are such a great resource on this relatively rare subject! for example I asked my friend who is a doctor, about affects of apnea diveing, but he didn't know much, this site provided pretty comprehensive information about that, so thanks once again Deeper Blue!
I bring this old thread up again for little focusing.

What are differences with CO2 narcosis, nitrogen narcosis (scuba one?) and O2 toxiety? What kind of symptoms, etc? Is it more usual to get CO2 narcosis when freediving, or nitrogen one?

Getting little confused with all these terms.

Hi All,

The nitrogen narcosis is the most common one.

When I've experienced it, it was on usualy at the begining of the deep dives season, when you're not familiarized anymore with it.

I also noticed that when you are "inactive" during your dive, you're more sensitive. The biggest I got was during testing in a flooded hyperbaric chamber. I had nothing to do, and I didn't foccused on anything...I was totaly waisted at 90m!!!!! When you are on the sled, you have to think about the brake, the parachute etc...

In constant or FI, like Eric said, it happens mostly when you start the ascent.
My opinion is that you are very focused in these disciplines, so you're less sensitive to narcosis. It's like deep air scuba diving, if you have a plan in your head, you'll delay the signs and symptoms of it. For a while....

O2 toxicity is very dangerous, because you don't feel it coming, and the black out is almost imediate. You have a few seconds after the first "shakes" to react. But it seems that it doesn't happen that often.

I'm in agreement with Mssr. Buyle in that an inactive diver will more often experience a narcotic effect than an active diver, and possibly that the activity itself masks the nonset of narcosis.

I say this with personal experience, having gone through several episodes while doing deep, very deep working dives, and going to different gas mixtures while decompressing. At varying depths and with varying physical states, ie, fatigue, cold, hunger, etc, the narcosis would present itself at different times and depths than at times experienced the day before. What is interesting, if you want to call playing guinea pig interesting, is that some of these occurances were while on surface-supplied air. I don't remember reading about that in my NAUI basic class reader...

Suffice it to say that the effects of narcosis, nitrogen or otherwise, is not something to strive for. As was pointed out in these earlier posts as well as in a couple of threads specifically dealing with SWB and the like, the situations and results are rarely similar between two persons and must be taken into account by that individual in their dive plan.

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