Funny thing is, if you use a home device to measure BP it's recommended that you not have any stimulants beforehand (i.e. caffeine, nicotine, etc.), and that you sit quietly in a relaxed environment for at least 5 minutes before taking your BP readings.
When you go to a doc in the middle of the day you've already had 3 cups of coffee, you're stressed out from the traffic on the drive there, then you walk however far to get into the office and have the additional stress of the fact that it's a doctor's appointment. You sit in the waiting room doom scrolling, listening to screaming kids and bellyaching people until 45 minutes past your appointment time, which has you steamed because wtf, my appointment was 45 minutes ago. They finally take you in, put you on the scale, which shows 5 pounds heavier than your actual weight because you're fully clothed, stressing you out further, and then they slap a BP cuff right on you and take a reading. Gee, my BP is elevated? You don't say?!? 😆