Effects of decaffeinated coffee on my blood pressure

In these experiments, I used an upper arm cuff home blood pressure monitor to measure my blood pressure on an empty stomach, after drinking a large cup of decaffeine coffee.

I used a filter coffee machine to prepare a large cup of coffee, made with decaffeinated ground coffee. The process was exactly the same as my experiment to see if caffeine coffee affected bloood pressure, except for the type of coffee, which in that case was obviously a standard caffeine coffee. In the current experiment, the coffee was decaf.

Here are my results:

Time	Upper (systolic)	Lower (diastolic)
10:10	124	83
10:12	118	82
10:15	125	85
10:19	126	81
10:22	126	80
10:25	125	81
I DRANK THE COFFEE AT THIS POINT
10:27	122	79
10:29	126	79
10:31	116	78
10:33	119	76
10:36	112	75
10:38	119	78
10:41	117	78
10:45	117	78
10:50	118	78
10:58	123	79
11:05	126	82
11:12	122	84
11:17	122	90
11:23	125	79

Here is the data as a graph showing the effect of de-caffeine coffee on blood pressure:

Before drinking the coffee, my blood pressure was fairly stable at around 125/82. However, at 10:31, around 5 minutes after drinking the decaf coffee, my blood pressure fell to 116/78, and fell even further at 10:36 to 112/75.

For 10:31 to 10:50, my blood pressure was below the starting blood pressure of around 125/82. From 10:58 until the end of my experiment, blood pressure had returned to near the starting level.

It appears from these results that drinking the decaffeinated coffee reduced my blood pressure for a period of around 25 minutes before blood pressure returned to normal.

Now, whether this is due to the decaf coffee itself, or some other factor involved remains to be seen. For example, it may well be that the decaf coffee itself has no effect on blood pressure, and something like the heat in the drink was responsible.

As a follow up experiment, I need to drink an equivalent volume of hot water.

That will be my next experiment.