Re. Yoga: contra-indication re. headstand and High Blood Pressure?
Answer: Although headstand is very hygienic for some people it is not so for everybody. Usually folks with big blood pressure which is controlled are able to do most yoga inversions to some point.
The reason why it is hazardous to do headstand in situations where on earth blood pressure is not controlled is because Headstand inverts the pattern of blood pressure contained by the body increasing it in the team leader and dropping it in the foot.
The blood pressure at the top of the head increases from 100/60 mm Hg(millimeters of mercury) within a standing position to 150/110 mm Hg in the Headstand.
The blood pressure of the foot in a standing position will be nearly 210/170 mm Hg and it will drop to 40/0 mm Hg in the Headstand.The blood pressure will remain equal at 120/80 mm Hg at heart level.
Here is a site that explains giant blood pressure and yoga inversions:
http://www.yogajournal.com/practice/594
I have be attending yoga classes for about 5 years immediately. Our teacher, who is over 80 believe it or not, have always told us that she never have and never would include the head stand within her classes because of the high blood pressure risk/connection.