to nap or not to nap?

[donnad]

i will be going on a 2-day liveaboard, with a possible 5 dives on day 1 and 2 dives on the second day. as far as risk for DCS, is it a bad idea to take a nap in the afternoon of that first day, like after the first three dives, then dive again at 5:30pm and 9pm?

 

[bennedc]

I don't think the nap matters, other than slowing metabolism for off-gasing. As long as you follow your no-deco times and take advantage of surface intervals, you should not have a problem. Hubby and I did Blackbeards, where we were diving 4 times each day. Just remember, by the end of the day, you will probabaly be limited by no-deco time rather than remaining air. Just pay close attention to the computer. I'd say if you're tired, take a nap!

 

[vladimir]

I think napping between dives is not optimal for off-gassing; some light activity is recommended. Here's a thread on the subject:
http://www.scubaboard.com/showthread.php?t=7234&highlight=sleep+nap+off-gas

 

[donnad]

thanks for the info. i think i'll try to avoid the nap.

 

[Dr Deco]

Hello donnad: This is just a bit modified from an earlier response.

Activity and Nitrogen Washout

The washout of inert gas is governed to the greatest extent by the flow of blood through the tissues (muscle fat, and connective tissues). Blood flow is the primary determinant.

This washout is promoted when the flow of blood is large such as with physical activity) and reduced with light activity (such as sitting or sleeping). At NASA, we have studied the effect of gas washout in critical tissues (as determined by incidence of DCS) as a function of body activity. Thus we determine exchange by studying the response to decompression.

The effect on blood flow is inferred, but the effect of exercise on DCS risk is very large as can be determined from depressurization experiments. This effect of physical activity on DCS incidence is directly quantifiable. It is not theoretical.

Napping and Nitrogen Washout

When one is up and around, blood flow is greater than when seated, and it is much greater than when you are sleeping. Blood flow, and therefore gas washout, is lowest during sleep. It is for this reason that I do not recommend that divers sleep during the surface interval between dives. Nighttime sleep at the end of the day is a different matter. That sleep is necessary, but then one has 7 to 8 hours for gas washout.

Dr Deco :doctor:

The next class in Decompression Physiology for 2006 is September 16 – 17. :1book: http://wrigley.usc.edu/hyperbaric/advdeco.htm[/SIZE]

 

[the_cat_keeper]

i will be going on a 2-day liveaboard, with a possible 5 dives on day 1 and 2 dives on the second day. as far as risk for DCS, is it a bad idea to take a nap in the afternoon of that first day, like after the first three dives, then dive again at 5:30pm and 9pm?

Hi, Donnad,

Just curious... what made you asked the question? I would never have thought about napping being undesirable... in fact, I always napped between dives!

Cat.

 

[dumpsterDiver]

I often "cat nap" on multi-day offshore trips. A little oxygen, and a motrin and a 30-minute nap does wonders for a CO2 headache and makes me feel much better, even if I'm not hurting. Getting out of the wetsuit and under a blanket in the sun and totally warming up and even starting to sweat helps me to recover for the next 2-4 dives of the day.

I usually try to do minimum of 90-minute SI for the multi-day trips when diving from sunrise to sunset. So I'm only sleeping for a part of the Surface Interval.

 

[Dr Deco]

Hello dumpsterDiver:

The problem with a catnap during the surface interval and immediately following the dive day is that it is possible that neurological DCS will be masked. One could even have a problem so severe that they loose consciousness or be paralyzed and they would never know it. A Motrin could also mask a problem.

I believe it best to stay awake for an hour to be certain that nothing bad will occur. In addition, the movement will help clear the dissolved nitrogen.

Dr Deco :doctor:

The next class in Decompression Physiology for 2006 is September 16 – 17. :1book: http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[dumpsterDiver]

Hello dumpsterDiver:

The problem with a catnap during the surface interval.... One could even have a problem so severe that they loose consciousness or be paralyzed and they would never know it. ...A]

I'm sure if I had a problem that severe I would wake up and tell someone!

 

[Dr Deco]

The truth is, some divers have been found unconscious when their buddies thought that they were simply sleeping.

Not hypothetical!