Hi Poiseidon,
Breathing in a paper bag is really helpful only when you have hyperventilation. In hyperventilation, you are breathing too fast and too much, leading to lower level of CO2 in your blood, because you breath it out too much. The paper bag helps you to breath back in a part of the CO2 you have released out, and less oxygen/more CO2 is taken in, and it rebalances your blood pH ( hyperventilation leads to respiratory alcalosis -
http://en.wikipedia.org/wiki/Hyperventilation#Treatment ) .
However, fast and shallow breathing, even if not caused by hyperventilation, can be linked to anxiety. What I think had been beneficial for you when you did this, is what I experiment when meditating. The focus on your breath, and the slowing down of your breath cycle, is what had a calming effect on you. I suggest you try breathing exercise/meditation without the bag, just to see if you can get the same calming effect, without the risk of oxygen deprivation ( unless your physician have diagnosed you with an hyperventilation syndrome, but it does not seem to be your case). Slowing down the respiratory cycle sure does have a calming effect on me, and I never have used a paper bag, which I think may cause some harm if done often because of the oxygen deprivation.
I meditate for years, and made it a daily practice in my life, and it helps in every aspect of my life - calm, serenity, clarity of mind, focus, sense of connecting with life, relationship, social interactions. The benefits you mentioned from your paper bag experiment are along that line as well. Every morning, I meditate for between 10 to 20 minutes. This is what helps me the most, more than any supplement ( my most severe POIS symptoms are emotional ones, like irritability, anxiety, mood swings, .... so, yes, calming techniques are quite relevant in POIS , at least for me ).
Meditating doesn't have to be complicated. For those interested, I can share a simple meditation technique I use almost every day, which is an ancient one and easy one, called the 4X4 breathing. Sit in a comfortable position, back straight ( can be on a chair - the lotus or half-lotus position is really not a must!). Not lying down, it is not the best for keeping the focus. Then, depending on your lung capacity and your experience, you count in segment of 3, or 4. First segment, the in breath, you slowly count "1-2-3", than same length of time, you hold your breath for " 1-2-3", than same slow "1-2-3" on the out breath, then hold ""1-2-3" on empty lungs. This is one cycle, and then, breath in again. When more able to slow down cycle, you can count in segments of 4. Ten cycles is very calming. 20 cycles is very, very calming. When I am very anxious and tensed, 40 cycles can be necessary, but that is becoming rare, because there is a cumulative benefit at doing it every day.
The most calming part of the cycle is the out breath and holding on empty lungs. That is why some are doing 3 segments only (inhale - exhale - hold ). I prefer the four segments, but there is no law in this, one has to try and see what is effective for himself. The only thing, when you are very tensed, you may sense a little anxiety when holding your breath after the exhale, lungs empty. If you are too anxious to inhale before it's time, just accelerate the whole cycle rhythm a bit, and with time, it will be easier to slow down.
Let me know of the results if you decide on giving it a try.
