What interruptions at work really cost you

An interruption at work costs more time than the interruption itself takes. What steals time isn’t the thirty seconds you spent answering the question or reading the note — it’s the return afterward. Your brain doesn’t leave what you were interrupted in the middle of as easily as you leave the room, and some of your attention remains on the old task while you try to get started on the new one. Psychologist Sophie Leroy has given the phenomenon a name: attention residue — a cognitive echo that lowers your performance on what you return to, long after the interruption itself is over.

The colleague at the door is rarely the real problem

It’s easy to blame the interruption: the email that pops up, the colleague who asks a quick question, the phone that lights up. But what really costs you time doesn’t happen during the interruption — it happens afterward, in the minutes when you’re back at the task but not really there. Attention doesn’t work like a switch that flips between on and off. It slips, and some of it stays with what you just left.

That's why two identically long interruptions can cost you very different amounts. An interruption in the middle of a simple, almost completed task leaves hardly any trace. An interruption in the middle of something complex and unfinished can lower your focus long after you're formally back. If you're writing a lengthy argument in a document and are interrupted by a question in the hallway, it's not the question itself that costs you — it's the following minutes where part of the thought is still trying to land while you reread the same paragraph twice.

A cognitive echo that lingers

Leroy's research shows that the residue is not just a feeling of being distracted — it shows up in actual performance. People who are interrupted in the middle of a task perform worse on the next task than those who are allowed to complete their work undisturbed, even when they have the same amount of time and other conditions are the same. This explains why a workday full of short interruptions can feel more exhausting than a day with fewer but longer interruptions, even though the total interruption time is the same on paper.

Unfinished tasks leave a heavier mark

One of Leroy's most concrete conclusions is that the degree of residue is related to how unfinished the task was when the interruption occurred. The more unfinished the work, the harder it is for the brain to let go of it — and the further into the next task it follows. This makes the phone a particularly expensive source of interruption: notifications rarely appear when you're finished with something, but in the middle of writing an email or in the middle of a train of thought that has not yet landed. The same mechanism underlies much of what is described in the article about screen time at work — it's not the time you spend on the phone itself that is most expensive, but where in the workflow it intrudes.

How long does it stay on?

Gloria Mark has been studying recovery time after a work interruption for several years, and exactly how long it takes for concentration to return to the same level varies between studies — depending on how the interruption is measured, the type of task that is interrupted, and how “recovered” is defined. Figures circulating in different contexts should therefore be read as estimates from specific study designs, not as a universal number that applies to all interruptions. What is certain is the direction, not the exact number of minutes: an interruption in the middle of complex work costs measurably more than the seconds it visibly takes.

What you can actually do about it

You can't eliminate all interruptions — colleagues, meetings, and urgent matters are part of the job. What you can influence is how often you initiate them yourself. Every time you check your phone between two thoughts, you create the same residue that an external interruption would have produced, albeit completely voluntarily. This applies even when it only takes a few seconds to check — it's not the time it takes to hold the phone in your hand that's expensive, it's that you interrupt a task before it's finished and leave an echo of it behind you.

Building the habit of letting a thought or task finish before you switch is therefore the single change that makes the most difference over a workday, more than chasing away colleagues or turning off all notifications at once. It's not about never being interrupted — it's about stopping being the one who interrupts yourself unnecessarily. We go over the basics of how to build it in practice in the guide to focus at work .

The Zenith Protocol is a 30-day protocol that trains you to eliminate the self-initiated part of interruptions—the impulse to check your phone in the middle of a thought that isn’t yet complete. It can help you build longer, more consistent periods of focus. It’s free to get started.