I got a little freaked out by them. I was having 4 large bowel movements per day ... nice and dark. Massive headaches. I know I experienced others, just can't remember what they were. Just remember living on the toilet with major headaches.
That's when I decided to use a coach .. just to see if what I was experiencing is common.
Buteyko got rid of a lot of symptoms: Blurred vision, light flashes, waking up with numb and tingling hands. I went from being unable to lift my head off the pillow in the morning to waking up completely refreshed.