The readings you (or anyone) gets on a monitor aren't 'real' or 'true'.
That is, the readings you see aren't your arteries' operating pressures. So, '120' actually ISN'T 120 and '80' ISN"t really 80.
Why? - well, because they are merely the internal cuff-pressure when the cuff is tight enough to stop the flow of blood and when it's slack enough to let flow resume. But the internal cuff pressure isn't the same pressure that is applied to constrict the artery
, because much of it is absorbed in distorting the flesh at the cuff-ends, and much is lost in compressing sinews, and other elastic tissue before it even begins to be applied to the actual artery. that's simple 4th grade Physics, and why doctors have fallen for this elementary elephant-trap for yonx, is beyond me.
Secondly, even if they were 'true' they're not the pressures generated by the heart. They're quite simply not. (the 'indicated' systolic is higher and diastolic is lower... honest! - If you want the source reference for that I'll give it to you)
Thirdly, your wife and you will almost certainly have different readings on the left and right arms. And if you measure them at different times they'll be different too. (So 11.30 a.m. will be vastly lower than 6.30 p.m -unless you've been doing something stressful just before the morning one
(My wife has the distinction of being diagnosed as "hypotensive" and "Hypertensive" in the same hospital, in the same week, by two different Cardiologists.... One wanted to give her medication "to bring her blood-pressure down" and the other wanted to give her the opposite "to bring her blood pressure up"... Fortunately I was there to stop the whole bl***dy nonsense.)
The only thing you can derive from monitor readings is CHANGE. And the change refers only to YOU. So, if your 'apparent BP' rises 25% over a period, then it reflects a true 25% change in your cardiac output pressure. -Similarly, if it falls 15%, then the same applies.
All the rest is medical mumbo-jumbo and can be ignored.
Why? because the reading you get at home with your wrist monitor depends only marginally on what your arterial pressure is. But two other factors act to influence the reading you get.
Oh, and just as a correction of another posting, the phenomenon you describe, simply can't be "explained by the so-called 'white coat-syndrome". That's what student nurses and medics are taught.... but if it were true then some explanation would have to be forthcoming as to why everyone doesn't exhibit it... And, of course, -there is none.
EDIT : The "not everyone gets white coat syndrome
..." posting below is, of course, a circular argument. If one accepts that "white coat syndrome" exists and is real, then it follows that if some exhibit it and some don't, then some "get" white coat syndrome and some don't.
But to explain the phenomenon by simply saying " some get it, and some don't" is just going round in circles. It's using an assumption to prove a theory.. See Euclid. Another example of pseudo medical mumbo-jumbo.
Anyone is just as entitled to say that the White Coat Syndrome is spurious, and the validity is just as true.