Hi fo1986
Not a pilot nor a medical professional but I had this problem in an earlier life.
There's a thing called IIRC an Ambulatory Sphygmomanometer which you wear for 24 hours. It records your BP, pulse etc half hourly during the day and hourly at night. I have used one twice and each time the highest readings were recorded in the clinic when it was fitted and removed.
Can't say if this is acceptable to the relevant authorities but I'm sure there will be someone along soon with a more professional answer for you.