Measuring blood pressure seems so straightforward. Stick your arm in a cuff for a few seconds, and there they are: two simple numbers, all the information you need to know whether you are in a healthy range or high enough that you should be taking one of the many cheap generic drugs that can bring down your blood pressure.
But the reality is more confusing, as I discovered recently when I tested mine.
It turns out that blood pressure can jump around a lot — as much as 40 points in one day in my case — which raises the question of which reading to trust.
Ever since I wrote about a woman who was in denial about her high blood pressure until she had a stroke, I have been worried that my blood pressure might creep up without my knowing it. I became interested again when I reported that a large federal study of people at high risk for a heart attack or stroke found…