Reducing the Effects of Nitrogen Narcosis
While no one is immune to nitrogen narcosis, there are some things you can do that might reduce its effects. First, be very careful about exceeding depths deeper than you're used to unless you have advanced training or are under supervision of more experienced divers. Even if you're an experienced deep diver but haven't done it in a while, it's a good idea to work up to a deep dive by making a few progressively deeper “rehearsal dives.” Be sure to practice the tasks you'll perform on the deep dive, too.
Often, especially when on a holiday, we can't always choose our buddy, and even if we can, we aren't always that discerning. However, when deep diving, it's important that you both know and trust your buddy. Prior experience with an individual gives you a “baseline” for what constitutes normal behavior. This insight will make it easier for you to recognize signs of nitrogen narcosis sooner than you might with a buddy whom you don't know well.
It may seem obvious, but deep diving requires use of a high-quality, well-maintained regulator. A poor-performing regulator can cause stress that, in turn, can exacerbate narcosis. So, make sure that your equipment is in top working order, and has been serviced within a reasonable period of time. One way you can get optimal performance is by remaining relaxed and moving in a slow deliberate manner.
Another common-sense guideline is to avoid drinking alcohol or taking any drugs for at least eight hours before diving. If you must take drugs, never take them for the first time before diving. Always know what effect a drug has beforehand. If the drug has a psycho-active effect or gives you a dry mouth, don't take it before making a deep dive. It could greatly increase the likelihood or effects of nitrogen narcosis.
Remember the KISS principle: Keep It Simple, Stupid. A simple dive plan means that you won't overload yourself with too many tasks. When deep diving you can't help but be impaired to some degree. Trying to accomplish too much will only increase the likelihood of poor performance or forgetting something.
Always try to begin a deep dive in a calm, relaxed frame of mind. Consider using the mental rehearsal techniques detailed later, and — most importantly — never hesitate to call off the dive if for any reason it just doesn't “feel right”.
Deeper water almost always means colder water, so wear adequate exposure protection. Remember, your wet suit will lose some of its effectiveness on a deep dive because of compression. Studies have documented that nitrogen narcosis can suppress the shivering response. This could lead to a false sense of your true state of thermal stress. In turn, moderate hypothermia can exacerbate the mental impairment caused by nitrogen narcosis.
Heed the advice and insights from more seasoned deep divers. Experienced deep divers often report that narcosis is at its worst when first arriving on the bottom. Therefore, don't be too quick to get on with the dive; take a minute or two to acclimate once you're on the bottom. Stop, relax, check your air supply and equipment and confirm that your buddy is alright before proceeding.
Deep diving is not something you want to learn by trial-and-error. It's strongly advised that you take a formal deep diving course from an experienced instructor. In addition, most courses will have you perform a timed task, such as solving an arithmetic problem or opening a combination lock, at the surface, and then compare it with the time it takes you to do the same task at a depth of 100 feet or more. Interestingly, some divers are able to perform the task better at depth than at the surface, and then mistakenly conclude that they're immune or not very susceptible to narcosis. That's a dangerous and false assumption because, as numerous studies have shown, the reality is that their improved performance is merely the effect of practice, not any indication of reduced sensitivity to nitrogen.
When deep diving, especially, be sure to keep a vigilant eye on your buddy. Ideally, never let more than three or four breaths go by without visually confirming their location, and verifying his or her mental state.
Finally, there's the issue of descent rate. Researchers have evidence that correlates a rapid descent with an increased likelihood of nitrogen narcosis. Logically, then, to reduce your risk, you should avoid descending too rapidly. But it's not quite that simple. On the other side of the issue, evidence also shows that a rapid descent might help divers avoid decompression sickness by crushing gas micronuclei. As this issue is still under debate, the best advice is probably to descend at a deliberate but comfortable rate. Another way to perhaps prevent or control narcosis is to use a reference line to provide a constant visual orientation during the descent.