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Mental Effects/Changes at depth

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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New Member
Jan 10, 2003
I was wondering if anyone knew of instances or cases where divers have experienced psychological or psychomotor problems when they were at depth, such as in no-limits diving? I was thinking about the pressures (physical, physiological and psychological) involved with the discipline, and thought that they could perhaps synergistically combine to cause such problems...??
I have experienced hallucinations & paralysis on deep constant weight dives in cold water. I have warned other people about these problems but they all ignore the warnings.

Eric Fattah
BC, Canada

narcosis generally increases with depth, but it seems to be much more complicated than that. in my experience, it appears that your mental state can have a very significant bearing on the intensity of narcosis.

i've done some moderately deep dives with virtually no narcosis, but have felt strong narcosis on other dives to relatively shallow depths- of only 40m. (not very deep when talking about narcosis).

i can think of two such occassions....

the first happened when i accidentally scraped past a cliff face during a variable descent. this came as quite a shock, and unsettled me for a few moments, but i continued with the dive

the second time occurred when i had to spend an unexpectedly long time at the bottom of a variable dive before ascending.

in both cases, the increased mental tension seemed to trigger fairly intense narcosis. on both occassions the feeling went as soon as i left the bottom, and had gone by the time i reached 35m or so.

interestingly, many of my deepest dives (during which i felt hardly any narcosis) were done blind. i have wondered whether that helped because i didnt have a visual feedback to my brain which may have compounded the narcosis. i'm not certain whether this can happen...

Interesting alun, that you say that doing the dives blind may perhaps have decreased the effects of narcosis. I have always believed (well, at least from personal experience) that blind dives can increase levels of mental tension or stress, simply because there is less visual input and you are relying on kinaesthetic feedback to tell the story of what is happening. However i can see where you're coming from.
I also find that closing my eyes worsens the narcosis. While doing hangs at 30m, I have nearly fallen asleep (narcolepsy), and when I sense that feeling coming I must open my eyes, and the feeling diminishes. Also, narcosis, for me, is much worse in dark water, and much worse in cold water.

Eric Fattah
BC, Canada
hi Eric/Alun

Do you guys close your eyes on max depth dives, for relaxing. I know a few guys that do and have also noticed myself that I can keep calmer when diving with my eyes closed for max depth. Just wandering if you guys do.

well i could be wrong about that idea... perhaps the minimal narocsis i experienced on those dives was due to having a good mental state (relaxation) rather than the fact i was blind... it was just a thought i had.

i just do whatever feels right/natural at the time, i don't follow a strict pattern. but i only close them when i dont need to see where i'm going... eg nolimits, variable, free immersion. closing your eyes in constant weight could result in :blackeye :eek:


Yeah Alun I close my eyes when doing constant weight spearfishing I hold my gun out in front so it whacks the bottom before me, it has happened a few times. But I rather close my eyes it feels like im lost for a little while.:cool: .

Closing eyes

Ivan, i hear you on that one. When night diving there is nothing like turning off your light and just hanging mid water for a few moments - magic!:D

Do you freedive at night. I have Scuba dived but thats it no night freediving.

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