Think about the last time you ran up a few flights of stairs. Your heart was pounding, you were breathing hard, and a few minutes later you were basically back to normal.

Now think about the last time someone talked down to you, or a client sent an email that made your stomach drop. That one didn't wear off in a few minutes. You might have still felt it on the drive home. You might have still felt it when you were trying to fall asleep.

It's the same body. So why does one kind of stress clear out quickly while the other hangs on for hours?

If you usually handle pressure well in the moment, this is for you. You keep your voice steady, you get through the call, you finish what you need to finish. And then later you realize you're still wound up, and you're not even sure why.

When it's over but you're not

Maybe you handled the situation well. You said what you needed to say. You solved the problem. There's no unanswered message and no decision left to make.

But a few hours later, your shoulders are still tense. You're restless. You sit down to enjoy something and you can't quite get into it. And now you're wondering why you're still reacting. You understand that it's over. What else are you supposed to do?

Perseverative cognition: the thinking that keeps the moment alive

The short answer is that when you keep thinking about a stressful event, your body responds to the thoughts a lot like it responded to the original event.

Dr. Jos Brosschot and his colleagues gave this a name: perseverative cognition. It means repeatedly thinking about something stressful, whether you're replaying what already happened or worrying about what's coming next. Their idea was that a stressful moment, by itself, usually doesn't last very long. What stretches out the stress response is the thinking that keeps the moment going afterward.

What the blood pressure studies show

Research from Dr. Laura Glynn and her colleagues at the University of California shows this clearly. They had people do different tasks that raised their blood pressure. Some were emotional, like doing math problems while the experimenter harassed them. Others were physical, like exercise. Exercise raises your blood pressure a lot, but it doesn't upset you.

What they found was that blood pressure was slower to come back down after the upsetting tasks than after the physical ones. And later, when people were asked to think back on the task, their blood pressure went up again, but only for the tasks that had been upsetting.

So how hard the body worked in the moment wasn't what predicted how long blood pressure stayed up. What mattered was whether the experience was upsetting. And upsetting experiences are the ones we tend to go back over. That's the difference between the stairs and the email.

What this doesn't mean

If your blood pressure goes up after a hard conversation, that increase isn't dangerous by itself. And replaying something in your mind doesn't mean you handled it badly or that something is wrong with you. It means your mind is keeping the event open, and your body is responding.

If you've had several of these moments over the course of a day, you can see how the replays pile up, and your body doesn't get much of a chance to settle back down in between.

Why "just stop thinking about it" backfires

Telling yourself to stop thinking about it usually doesn't work very well. Most people have tried that, and the thought comes right back.

What the research points to is giving your mind something else that really takes its attention. Glynn's team ran a second, smaller experiment. After a stressful math task, one group sat quietly. The other group was given something else to focus on, a task that took their attention. The group with something to focus on had better blood pressure recovery.

A few years later, Dr. William Gerin and colleagues looked at this again with anger. They had people remember something that had made them really angry, then sit for about twelve minutes, sometimes with distractions around and sometimes alone with nothing to do. When there were distractions, people had fewer angry thoughts, and most of that difference showed up in the first few minutes. The people who tend to dwell on things had the slowest blood pressure recovery when they had nothing to occupy their minds.

What strikes me about this is that sitting quietly is what most of us think of as calming down. But for something that stung, quiet can give your mind room to go right back to it.

Give your attention a job

Here's the tactic. Right after a stressful moment, give your attention a job.

It needs to be something absorbing enough that it actually takes your focus. Scrolling usually doesn't do it. Your attention skims, and it's easy to end up right back in the replay, or to find something new to get worked up about. You're looking for something with some structure to it.

That could be cooking something with steps you need to follow. It could be a word puzzle or a game that makes you think. It could be calling a friend about something completely unrelated and actually listening to what they're saying. Or it could be a walk where you're trying to figure out something specific, like how many houses have their porch lights on.

Go back to that client email. Instead of going straight back into your inbox, or sitting in your parked car replaying it, take ten or fifteen minutes and do something that needs you. You're not trying to force yourself to feel calm. You're giving your body a stretch of time where nothing is re-triggering it, so it can settle back down.

Timing matters

In that anger study, the biggest difference in angry thoughts showed up in the first few minutes. So the sooner you give your attention somewhere else to go, the better.

You're not trying to pretend it didn't happen. If there's something you need to follow up on, you can come back to it on purpose, later, when your body isn't still braced. You'll probably think about it more clearly then anyway.

When the same moments keep following you home

So if you've ever felt like you should be over something by now, and you're frustrated that you're not, it's not that you're too sensitive or bad at letting things go. Your body is responding to a stress that your mind keeps bringing back. That's something you can actually work with.

And if you start to notice it's the same kinds of moments that keep following you home, that's worth paying attention to. It may be that certain moments touch a sensitive area for you, which can be a signal that there's a deeper issue to address so you're not as easily triggered in the future.

In my next video, I'll talk about why you can be patient with everyone all day and still come home short with the people you love most.