I've had several bouts of narcosis. I primarily dive fresh water quarries that can get quite cold down below the last thermocline. From what I can remember, all the time I have experienced it, it was a combination of task overloading & narcosis. The first instance was my first deep dive in my AOW course I was using rental gear & had multiple problems during that dive (not enough weight so had to hand over hand pull myself down a descent rope, a weight belt that wouldn't stay up, lost a fin at 80ft & started to over- breathe my regulator). Needless to say that things got out of hand rather quickly. If not for an attentive DM assisting with the class, I would have bolted for the surface. He recognized the situation, got a hold of me & we made a slow ascent. Once we got to the safety stop, I calmed down. Of course at the time I didn't realize it was narcosis. I have since experienced narcosis to milder degrees on other dives in that quarry. Any more I notice it as an irritating "static buzz" (like listening to a radio with lots of static) in my head or a feeling that I can't expand my chest enough to breathe properly. My last bout was this summer the first time I tried to dive my doubles. Not realizing how negative those double steel 85's were, I released ALL the air from my wings. Needless to say, I got into a run away descent & was finally able to stop myself at about 95ft. I was quite lucky that I didn't rupture my ear drums on that one as I found I was struggling to equalize my ears, fill my wings & my drysuit. When I got stopped, once again, I felt like I could not expand my chest enough to get a full breath of air & thus aborted the dive. I am finding out that, for me, task loading, temperature & descent rate seem to greatly affect how badly I experience narcosis. I have dove to 124ft in the Caribbean & not experienced any noticeable narcosis, yet have experienced narcosis dozens of times at this quarry to one degree or another. As I gain more & more experience it also seems to help me to deal with the narcosis, so each dive to depth, there, is a little better than the last.