For the last several weeks, I have been having throbbing in my head when I lie down. It is not painful and eventually goes away. I am 50 years old and work out a lot, so I am physically very fit. My weight, cholesterol and blood sugar are normal. My blood pressure is a little high - classed as prehypertsensive. I take Lisinopril 5 mg, but am wondering if my blood pressure needs to be reevaluated.