Frequently referred to by divers as ‘getting narked’, nitrogen narcosis is a condition that affects people when breathing gas at high pressure, such as when a scuba diver descends to depths of 30 metres or deeper. The name derives from the Greek word ‘Narke’, which translates to ‘temporary loss of senses and movement’. Some divers feel that this narcosis is one reason to dive deep, where others feel that this is the very reason why they should stay shallow.
Nitrogen narcosis, or more accurately, ‘gas narcosis’ is related to increased solubility of different gasses in body tissues dude to the increased pressure at depth. Although it is most commonly named ‘Nitrogen Narcosis’, almost all breathable gasses are narcotic to some level, with the exception of helium, and possibly neon.
Sometimes nitrogen narcosis is referred to as ‘Martinis Law’ because diving at 30 metres is similar to drinking a Martini, and every additional 5 metres is another Martini. While at depth, narcosis has affects the body in ways such as; loss of focus, impaired co-ordination, disorientation, mild euphoria and a false sense of security. As narcosis is related to pressure, if you feel clear headed at 25 metres, but narked at 30 metres, if you ascend back to 25 metres you will feel clear headed once again. Some people may not feel it at 30 metres, and others may feel it strongly at 27 metres. The intensity can change from day to day, and you cannot develop a tolerance to it.
Nitrogen narcosis is not actually harmful in itself, it’s what divers may do when they are ‘narked’ that can make it become an issue. Because it gives you a mild euphoric feeling, some divers may get a false sense of security. I have had divers with me try to catch fish with their hands, and even had a student before who tried to catch a fish with their regulator second stage! Some just started laughing uncontrollably, whereas others might start digging in the sand to try and get their dive computer to register deeper than anyone else’s.
While acting a bit silly underwater is fine, narcosis can have some more sinister effects. This false sense of security can make people forget to check their dive computer, or your air. The most common cause for decompression illness is because divers do not check their air regularly enough, and when they run out, they panic and make a breath hold ascent instead of remembering their training (performing a controlled emergency swimming ascent, or a buoyant emergency ascent). The majority of experienced divers who run out of air and make a breath hold ascent are diving deep when they do it. Not regularly checking your dive computer or depth gauge can lead you to accidentally drop down too deep, or accidentally stay at depth for too long.
It is important that you experience narcosis with the first time with an instructor, as they will know what symptoms to look for. They will also know better how to deal with it themselves, and what to do if they feel you are too ‘narked’ for your own good. The deepest dive you can do as a recreational diver is 40 m (by PADI standards) and at this depth narcosis will be very strong. You should always attain proper training, such as the PADI Deep Diver specialty before trying to go to these depths. During the program your maximum depth will be slowly increased, and you will be given increasingly complex tasks to complete so you learn properly how to deal with the narcosis.
Many divers ask “if it is already so strong by depths of 40 metres, then how do divers cope when they go really deep?” As helium is non-narcotic, deep divers add helium to reduce to amount of nitrogen in the breathing mix, but this comes at a cost. Helium greatly adds to decompression times, and it is an incredibly expensive gas. However because of the dangers of diving to extreme depths, keeping a clear head is essential.
‘Nitrogen Narcosis’ was written by Mike