Thank you very much, Mark, for the very helpful advice. I really appreciate it. I will try to develop the good habits that you suggest for the sleeping posture.

I am not sure how to describe the treatment that the chiro is using; I am lying on my back, and she "presses" several points in the upper neck, in particular one sore point near the spine. She does that during half an hour, and as I wrote earlier it completely eliminates the headaches.