An interruption at work costs more time than the interruption itself takes. What eats your time isn't the thirty seconds you spent answering the question or reading the notification. It's getting back afterward. Your brain doesn't leave behind what you were in the middle of as easily as you leave a room, and part of your attention stays stuck on the old task while you try to get going on the new one. Psychologist Sophie Leroy has a name for this: attention residue, a cognitive echo that drags down your performance on whatever you return to, long after the interruption itself is over.
The coworker at your door is rarely the real problem
It's easy to blame the disruption: the email that pops up, the coworker with a quick question, the phone that lights up. But what actually costs you time doesn't happen during the interruption. It happens afterward, in the minutes when you're back at the task but not quite there. Attention doesn't work like a light switch that flips between off and on. It drifts, and part of it stays behind in whatever you just left.
That's why two interruptions of exactly the same length can cost you very different amounts. An interruption in the middle of a simple, nearly finished task leaves hardly a trace. An interruption in the middle of something complex and unfinished can drag down your focus long after you're officially back. If you're writing a long line of reasoning in a document and someone stops you in the hallway with a question, the question itself isn't what costs you. It's the next few minutes, when part of your thinking is still trying to land and you read the same paragraph twice.
A cognitive echo that lingers
Leroy's research shows that residue isn't just a feeling of being distracted. It shows up in actual performance. People who are interrupted in the middle of a task do worse on the next task than people who get to finish their work undisturbed, even when they have the same amount of time and the same conditions otherwise. That explains why a workday full of short interruptions can feel more draining than a day with fewer but longer ones, even though the total time lost to disruption is the same on paper.
Unfinished tasks leave heavier traces
One of Leroy's most concrete findings is that the amount of residue depends on how unfinished the task was when the interruption came. The more unfinished the work, the harder it is for your brain to let go, and the further it follows you into the next task. That makes your phone an especially costly source of interruptions. Notifications rarely show up when you've just finished something. They arrive in the middle of writing an email or in the middle of a train of thought that hasn't landed yet. The same mechanism is behind much of what's described in the article on screen time at work. The most expensive part isn't the time you spend on your phone itself but where in your workflow it breaks in.
How long does it last?
Gloria Mark has spent years studying what happens to recovery time after an interruption at work. Exactly how long it takes for your concentration to get back to the same level varies between studies, depending on how the interruption is measured, what kind of task is interrupted, and how "recovered" is defined. So the numbers that circulate in various places should be read as estimates from specific study designs, not as one universal figure that applies to every interruption. What's certain is the direction, not the exact number of minutes: an interruption in the middle of complex work costs measurably more than the few seconds it visibly takes.
What you can actually do about it
You can't eliminate every interruption. Coworkers, meetings, and urgent questions are part of the job. What you can control is how often you start them yourself. Every time you check your phone between two thoughts, you create the same residue an outside interruption would have, except you do it entirely by choice. That holds even when checking only takes a few seconds. What's expensive isn't the time the phone spends in your hand. It's that you break off a task before it's finished and leave an echo of it behind you.
So building the habit of letting a thought or a task finish before you switch is the single change that makes the biggest difference over a workday, more than chasing coworkers away or turning off every notification at once. It's not about never being interrupted. It's about no longer being the one who interrupts yourself for no good reason. We walk through the basics of how to build this in practice in the guide to focus at work.
Zenith Protocol is a 30-day protocol that trains away the self-started part of interruptions: the urge to check your phone in the middle of a thought that isn't finished yet. It can help you build longer stretches of uninterrupted focus. It's free to get started.