I've now been doing the proper Buteyko breathing method for 5 days. Initially I was doing the control pause wrongly but now that I know what I'm doing my morning CP has stayed around 20. I'm ridiculously tired which started a few days ago and I went out and didn't sleep well at a friend's house so that didn't help. Anyway, the CP isn't dropping when I get tired so I'm assuming that I am both adapting in some way while at the same time being run down so its cancelling out perhaps? I do feel more calm, though that doesn't mean that the theory behind the method is responsible, however, I've been researching the type of breathing advocated by the Buteyko breathing technique (abdominal and nasal breathing with 'reduced*' minute ventilation), and this does scientific support behind it.
*Not necessarily reduced but average people today are generally thought to be breathing too much and this method aims to reduce that amount to a more 'healthy' level. This definitely does have health benefits to it, I'll be making posts on that at a later stage.