Episode 44 · 27 minutes
A World Without Email: Reimagining Work in an Age of Communication Overload
by Cal Newport, 2021
A World Without Email argues that the inbox was never the real problem: the trouble is a way of working built on constant, unscheduled conversation, and the fix is deciding in advance how work is assigned, tracked and discussed. Nora separates the industry figures the book opens with from the small field and lab studies beneath them, and finds the diagnosis holds up in miniature while the cures are still untested. For neurodivergent leaders: moving coordination into boards, office hours and set meetings takes the burden off individual willpower, though no interruption study has yet recruited an ADHD sample.
- Running time 26:38
- Published 2026-11-04
- Topics Time and focus, Communication, Executive function
- Reader Nora
Transcript
The whole episode in text, 111 lines. Miles and Nora are synthetic voices reading a script approved by Logan Williamson, LPC.
Read the full transcript
Miles: Late in twenty ten, President Obama appoints Nish Acharya to run innovation and entrepreneurship at the Department of Commerce. The job means coordinating twenty six federal agencies and more than five hundred universities around a hundred million dollars of funding.
Miles: A few months in, on a Tuesday morning, a note comes round from the technology staff. A virus is in the network and they're taking it down. Two days, maybe. Then Homeland Security advises keeping it dark, and every computer, laptop and printer in the office is marked for destruction. The staff call it Dark Tuesday. The outage lasts six weeks.
Miles: And his work gets better. He goes out and meets people face to face. His meetings run long enough to get to the bottom of hard problems. He finds empty stretches in his day, and out of them come two ideas that set his agenda for the following year.
Miles: Today: A World Without Email, by Cal Newport. In two sentences: the trouble was never the inbox, it's the way of working that grew up inside it, one endless unscheduled conversation everybody keeps half an ear on. The cure is deciding in advance how work gets handed out and talked about, so the conversation can stop. And later Nora argues that one group pays more for that conversation than the rest, and shows you where the evidence runs out.
Miles: Sixty Books. Presented by Stoar Consulting and Coaching.
Miles: Book forty four, and this is Sixty Books. I'm Miles. The terms haven't moved: one management book per episode, sixty chosen from the best of the last hundred years, each one asked the same two questions. What does it hand a leader or a team whose minds don't run on the factory settings. And what survives now that AI sits in the working day. Nora has the research, and she's met this author before.
Miles: Nora, Burkeman left us last time with the day getting eaten, and a strong hint that the schedule wasn't the one doing the eating.
Nora: It's whatever has no slot. A calendar holds the things somebody agreed to in advance. What fills the gaps between them is the message nobody scheduled, and this whole book is about that message.
Miles: And it's Newport again, two books after Deep Work.
Nora: Same author, different target. Deep Work handed the job of guarding attention to the individual. When this one came out, he told an interviewer he'd naively assumed organizations would make room for focus once they understood its value. They didn't, so this time he goes after the way the office runs.
Miles: So the sequel blames the office.
Nora: Yeah. The sequel blames the office. Which, for a productivity writer, is like a diet author admitting the problem was the vending machine bolted to the wall outside your door.
Miles: And restocked all day.
Nora: Every six minutes, by one count. Hold that number. It gets a hard look later.
Miles: Back to the man with no network. What does the book make of him?
Nora: He's the opening scene, and Newport tells it as a puzzle. Acharya told him the first stretch was close to hell. He worried about missing something that mattered, and arranging a meeting took real effort. But nothing stopped. He went and saw people, he had room to think, and the work improved.
Miles: And Newport's reply?
Nora: That most of what the inbox did for him could have gone to an assistant: the daily checking, the meeting logistics. Acharya was stunned by the idea that he might not need email at all.
Miles: Which is a large claim to build on one federal office.
Nora: Fair, and the book knows it. Acharya's a story, not a study. He's there to make one thing visible: the stream of messages and the work itself are two different activities that have grown into each other.
Miles: And the stream has a name.
Nora: The hyperactive hive mind. His definition is a workflow centred on ongoing conversation, fed by unstructured and unscheduled messages. And he gives it its due. It's simple, it's flexible, nobody needs training, and in a very small group it's quick.
Miles: Then where does it go wrong?
Nora: Past a handful of people. The introduction backs that with four figures: a hundred and twenty six work emails per worker per day by twenty nineteen, a check of email or chat about every six minutes, seventy seven inbox checks a day in a field study from the University of California, Irvine, and more than three hours a day on work email. Four figures of four quite different kinds, which is a job for the evidence segment.
Miles: The author, briefly, since he had his hearing two books back.
Nora: Briefly. Cal Newport is a full professor of computer science at Georgetown, and his research is the theory of distributed systems: what separate machines on a network can and can't get done together. And here the field matters. Newport has described how theorists in his area study asynchrony, meaning no real time back and forth, and found that taking the real time exchange away makes coordination harder and costs many more messages. This book carries that from machines to people. A meeting two colleagues could settle in a two minute conversation turns into a dozen emails.
Miles: And the book itself.
Nora: March of twenty twenty one, three hundred and twenty pages, in two parts. Part one is the case against: email reduces productivity, email makes us miserable, email has a mind of its own. Part two is four principles for working without the hive mind: attention capital, process, protocol and specialization.
Miles: That third chapter title is doing a lot of work.
Nora: It's the history chapter. In Newport's account, in the nineteen eighties a large computer maker installs internal email for its own staff, expecting it to replace memos, notes and voicemail one for one. In the first week the traffic runs five to six times what anyone predicted. His reading is that nobody chose the hive mind. It grew, faster than any group could have planned it.
Miles: And once it's there, it feeds itself?
Nora: He borrows the mechanism from Leslie Perlow at Harvard Business School, who calls it a cycle of responsiveness. Somebody replies faster, colleagues come to expect it and ask for more, replying fast becomes the price of looking committed, and the loop tightens without anyone deciding it should.
Miles: The case against, then, in the book's order.
Nora: Chapter one opens on a founder Newport calls Sean, who ran a seven person software studio in London. Email at first, from waking until night. Then they moved to a chat tool, opened it to their largest clients, and Sean ended up working until one in the morning, because those were the only quiet hours left. When he checked which feature of the new tool his team used most, the winner was an add-on for posting animated GIFs.
Miles: So the busiest corner of the new system was the reaction pictures.
Nora: It was. Two of his project managers then quit, burned out, in his word.
Miles: And the research under the stories?
Nora: Starts old. The first published measure of what it costs to switch between tasks is Arthur Jersild's, from nineteen twenty seven: people alternating between two tasks were slower than people doing one at a time. Then Newport brings in Gloria Mark at Irvine, and a paper from twenty oh four whose title he clearly enjoys: Constant, Constant, Multi-tasking Craziness. Victor González and Mark shadowed fourteen analysts, developers and managers at one outsourcing firm, four hundred and seventy seven hours of observation in all. People stayed with one stream of work for about eleven and a half minutes before switching. They were interrupted about twenty five times a day.
Miles: And email was the main culprit.
Nora: Not in that study. Colleagues walking up to the desk, and phone calls, pulled people off task more than electronic alerts did. Keep that for the end of the episode.
Miles: Chapter two is misery.
Nora: And Mark ran the experiment that chapter's argument invites. In twenty twelve, with Stephen Voida and Armand Cardello, she switched off email for thirteen staff at a scientific research organization for five working days, against a few days of normal use, logging every move between windows. Without email, people switched windows less often and stayed in each one longer. Heart rate monitors pointed toward lower stress, but only seven people gave usable readings, and the difference fell short of significance.
Miles: So the switching result is solid and the stress result is a lean.
Nora: Within thirteen people, yes. Chapter three is the history we've covered, and then part two turns to the cure.
Miles: Attention capital.
Nora: It starts from Peter Drucker, who coined the phrase knowledge worker in nineteen fifty nine and argued in the sixties that such workers can't be closely supervised and have to direct themselves. Newport's complaint is that management heard that as permission never to look at how the work moves. Each person became a black box, and the hive mind filled the space.
Miles: And the alternative?
Nora: Ford. Before nineteen thirteen, the book says, putting a Model T together took more than twelve hours of labor. Once the cars moved past workers who stayed put, it took about ninety three minutes. Nobody's effort changed. The arrangement did. Newport's claim is that knowledge work has never had that moment, and that its raw material is the brain's capacity to focus, which he calls attention capital.
Miles: That analogy will make some people nervous.
Nora: He says so himself. Line work was draining, and people became extensions of the machinery. What he takes from Ford is the willingness to experiment with the arrangement, not the conveyor.
Miles: Process.
Nora: Decide in advance how each recurring kind of work moves. His main tool is a task board: columns for stages, cards for tasks, and the talk about a task lives on its card, not in anybody's inbox. One marketing firm in the book gave every client its own board. Add a short regular status meeting where each person says what they did, what's next and where they're stuck, and a lot of messages never get written.
Miles: Protocol.
Nora: Rules for when and how coordination happens. Office hours for questions that can wait a few hours. A way of booking a meeting that doesn't need a thread. Client terms written into the contract, so everyone knows when to expect an answer and how to reach someone in a real emergency.
Miles: And specialization.
Nora: Do fewer things, better, and own them. Move the administrative load to support staff, organized so they don't become a fresh source of interruptions. And work in sprints, often two weeks on a single goal, with outside contacts told in advance that you're hard to reach.
Miles: Huh.
Miles: The evidence. Start with those four figures.
Nora: They arrive together, and they aren't alike. The hundred and twenty six is an estimate, and that's the book's own word. The six minutes is a time tracking company's data on more than fifty thousand of its own users, the median gap between check-ins, and everyone in that pool installed software to watch their own time. The three hours is a software company's annual survey of about a thousand American workers estimating their own day. All three are industry data. They point the right way, and none was built to measure precisely.
Miles: And the seventy seven?
Nora: That one's different. It's peer reviewed, and unlike the residue study two books back, it watched real inboxes. Mark again, with Shamsi Iqbal, Mary Czerwinski and colleagues, at a computing conference in twenty sixteen. Forty workers in the research division of one large company, about twelve days each, software logging every switch to email and a heart rate monitor worn on the chest. The more time someone spent on email in a given hour, the higher their measured stress. The more time on email across a day, the lower they rated their own productivity.
Miles: And the cure everyone recommends is batching.
Nora: Which they tested. Eleven of the forty were batchers, with most of their email packed into a few hours. Batching made no detectable difference to stress, and batchers rated themselves more productive only on heavy email days. It's correlational and from one workplace, so it can't tell you what causes what.
Miles: Is there anything with a manipulation in it?
Nora: One. Kostadin Kushlev and Elizabeth Dunn, Computers in Human Behavior, twenty fifteen. A hundred and twenty four adults in Vancouver, about two thirds of them students, each spending one week told to check email three times a day and one week with no limit, in random order. In the limited week they reported lower daily stress.
Miles: By how much?
Nora: Not much. About one point four six against one point five five, on a scale from zero to four. And the limited week wasn't three checks: people averaged nearly five, against twelve and a half when nothing was limited. The authors call their study exploratory, and write that checking less often is by no means a panacea. Then a lab result that points somewhere uncomfortable. Mark again, with Daniela Gudith and Ulrich Klocke, twenty oh eight. Forty eight people, mostly German students, answered a stack of work emails, sometimes interrupted every couple of minutes and sometimes left alone. Interrupted, they finished faster, with no more errors. They also reported more stress, more frustration, more time pressure and more effort.
Miles: So the work survives and the person pays.
Nora: Over twenty minutes, in a lab. Which is close to Newport's whole argument in miniature.
Miles: And the prescriptions?
Nora: The thinnest layer. The four principles rest on interviews, company stories, and a survey of his own readers in twenty nineteen, more than fifteen hundred replies from people who chose to answer, and he calls their testimonies anecdotal himself. I found no trial of a team moving from the hive mind to boards and protocols and measuring what happened. One reviewer, in April of twenty twenty one, found the diagnosis more convincing than the cures and thought the title promised more than the book delivers, which Newport himself concedes.
Miles: Tier statement, then.
Nora: This is practitioner literature, a working computer scientist's argument for general readers, not peer reviewed research. The diagnosis stands on small field studies, a short lab experiment and one modest randomized crossover, which agree on direction and report small sizes. The cures stand on cases. So on my running score, the claim that the hive mind costs attention and calm has held up in miniature, and the claim that these principles fix it hasn't been tested. Neither of those is a mark against the author.
Miles: Our half.
Nora: And it opens with a claim, so let me mark it as one. Unscheduled interruption is the most expensive thing an open inbox does to people with ADHD, as a group, and this book hands you the currency to price it in. That goes past the evidence, and I'll show you where.
Miles: Start with what you went looking for.
Nora: An interruption study with an ADHD sample. Every email and interruption study in this episode recruited general workers or students. I didn't find one, at work or in the field, that recruited adults with ADHD and measured what interruptions cost them. So the plain answer is that nobody has priced it directly.
Miles: Then what is there?
Nora: Lab work on distraction, and one study comes close. Sophie Forster, Nilli Lavie and colleagues, Neuropsychology, twenty fourteen. Seventeen adults diagnosed with ADHD through a London clinic or support groups, and a matched comparison group, doing a letter search on a screen. On one trial in ten a bright cartoon character appeared that had nothing to do with the task. It slowed the ADHD group significantly more than the comparison group.
Miles: So an irrelevant thing pulls harder.
Nora: In that group, in that lab, on that task, yes. And when the search was made more demanding, the cartoon's pull dropped, as much for the ADHD group as for everyone else. A small sample, fifteen of the seventeen tested a day after their last dose of stimulant medication. Group findings, not a description of anybody in particular.
Miles: And alerts in daily life?
Nora: Kushlev and Dunn again, with Jason Proulx, twenty sixteen. Two hundred and twenty one undergraduates, not an ADHD sample, one week with phone alerts on and one week with them silenced, in random order. With alerts on, they rated themselves higher on a checklist of inattention and hyperactivity symptoms. The differences were about a tenth of a point on a four point scale, and the authors say outright that this doesn't show notifications cause ADHD.
Miles: So here's the argument.
Nora: Here's the join, and it's mine. If a salient, irrelevant interruption costs adults with ADHD more in the lab, and if alerts raise everyone's self rated distractibility in daily life, then the hive mind probably doesn't charge a flat rate. It charges more to the people whose attention gets pulled hardest. Attention capital gives you the unit. Nobody has done the arithmetic.
Miles: And why would this book help where the usual advice doesn't?
Nora: Because the usual advice is personal discipline, and the evidence on personal discipline is unkind. Told to check three times a day, Kushlev's participants managed about five. Batching on your own didn't move stress in the Irvine data. Newport takes the decision out of the individual's hands and puts it into how the team coordinates: office hours, a board, a fixed meeting. A protocol works for the person whose attention is pulled hardest without that person disclosing anything or asking for anything.
Miles: Cautions.
Nora: Two. The first is that nobody has tested a process and protocol workflow with neurodivergent employees as the outcome. Forster's lab, Kushlev's students and Mark's offices are three separate literatures, and the line running through them is drawn by me.
Miles: And the second.
Nora: Protocols are only as kind as the people who write them. Office hours set by the busiest person on a team fit that person's rhythm. The book itself says the people a procedure affects should help design it. So build the board and the hours with the people who'll live inside them, and leave a way to reach someone when a question can't wait.
Miles: Right.
Miles: One minute, on our terms. A World Without Email says the inbox isn't the problem. The problem is a way of working built on constant, unscheduled conversation, and it spends attention and calm that nobody budgets for. For anybody leading a mind that runs on different settings, or working inside one, here's Monday. Find the one kind of request that throws off the most messages on your team and give it a home: a board, a form, a standing slot, anything but a thread. Set office hours for the questions that can wait, and say plainly how to reach someone when one can't. Write those rules with the people who'll follow them, not for them. And stop handing out check less often as personal advice, because the studies say it barely holds. Change the arrangement, so nobody has to win a willpower contest to get a morning's work done.
Miles: The machines.
Nora: The standing caution about these tools waits after the music, unchanged, so I'll point you there and spend this on what Newport's book makes of them.
Miles: Go on.
Nora: The obvious use is answering email faster, and there's a big field experiment on that. Sixty six large firms, about seven thousand knowledge workers, some picked at random to get an AI assistant built into the software they already used for email, documents and meetings, over six months. Those who used it spent about two hours a week less on email, from a starting point of nearly twelve, and worked less outside normal hours. But the same paper found no detectable change in how much work people did or what kind. It's a working paper that hasn't been through peer review, and it was run by researchers at the company that makes the tool. Read beside this book, the meaning is plain: the hive mind got cheaper to run, and it's still running.
Miles: So where would Newport put the thing?
Nora: On the process side, never the reply side. Hand it last month's thread about a recurring request and have it draft the form, the office hours note or the client terms that would have made the thread unnecessary, then rewrite that draft with the team. Describe how a piece of work moves and have it propose the columns for a board. Have it boil a long chain down to one card with the decision on it.
Miles: Send us out with something to try.
Nora: Before you let a tool write your replies, ask what the reply is for. A faster answer to the hive mind is still an answer to the hive mind. The better use is building the process that means the message never has to be sent.
Miles: That's A World Without Email.
Miles: Next time: Peopleware, by Tom DeMarco and Timothy Lister. Nearly everything Newport argues about shielding a working mind from interruption, two software consultants had in print in nineteen eighty seven, when the culprit was a ringing desk phone and an office with no door, and the trade has spent the decades since rediscovering it.
Nora: And in that shadowing study, people walking up to the desk pulled workers away more than any alert did, so the room was always half the story.
Miles: Thanks for the company in a crowded inbox, Nora.
Nora: Glad it was this one.
Miles: Onward.
Miles: Sixty Books is made at Stoar Consulting and Coaching. Logan Williamson is a Licensed Professional Counselor in Texas and Louisiana. You heard one book read closely, for people who run teams and the people on them. It wasn't coaching, it wasn't counseling, and nothing in it was a finding about you.
Nora: Sources for each claim are on the episode page, with the full transcript. Book forty five lands in two days.
Miles: A word on who made this, then one note. The voices you've been hearing are generated. There's no Miles and no Nora, nobody here holds a license in anything, and not a word of this was aimed at you in particular. AI helps draft every script, and Logan Williamson, a Licensed Professional Counselor in Texas and Louisiana, at Stoar Consulting and Coaching, edits each one and approves it.
Nora: And one note about the AI segment. The evidence that these tools help neurodivergent people at work is early. There are controlled trials now, but they measure things like conversation skill rather than how a job actually goes, and for work itself most of what exists is individual providers reporting success. So take it as promising and not proven. The tools also get rebuilt every few months, so whatever you set up today is built on something that moves.
Sources
Every claim in the episode, in the order it comes up, with where it comes from. 27 claims. Studies in psychology and medicine were checked on PubMed; everything else against the publisher, the paper or the original record.
See the sources
In late 2010 President Obama appointed Nish Acharya director of innovation and entrepreneurship at the Department of Commerce, a role coordinating twenty six federal agencies and more than five hundred universities around a hundred million dollars of funding. A few months in, on a Tuesday, the office network was taken down because of a virus; an initial fix was expected within days, Homeland Security then advised keeping it down, and the office's computers, laptops, printers and other devices with chips were to be destroyed. Staff called it Dark Tuesday, and the outage lasted six weeks. Acharya found the first stretch close to hellish, worried about missing important requests and found meetings harder to arrange, but his work improved: he met people in person, held longer meetings that helped him understand complex problems, had unscheduled empty time to think, and from it came two ideas that set his agenda for the following year.
Newport, C. (2021). A World Without Email: Reimagining Work in an Age of Communication Overload. Portfolio/Penguin. ISBN 9780525536550. Introduction, "The Hyperactive Hive Mind".
Verified against the publisher's reading sample of the Spanish edition: Newport, C. (2022). Un mundo sin e-mail. Editorial Reverté (REM / Reverté Management), https://content.e-bookshelf.de/media/reading/L-18283822-a2eb6f6279.pdf , which gives the appointment "a finales de 2010", the twenty six agencies, the more than five hundred universities, the hundred million dollars, the virus, the Homeland Security advice, the destruction of devices, "Martes Oscuro", "El apagón duró seis semanas", "bastante infernal", and "tuvo un par de ideas innovadoras que acabaron marcando su agenda del año siguiente".
Newport suggested that the daily checking and meeting logistics could have been handled by an assistant, making email unnecessary for Acharya's role, and Acharya was stunned by the idea of working without email.
Newport (2021), Introduction, as in item 1; Spanish reading sample as in item 1.
The book defines the hyperactive hive mind as a workflow centred on ongoing conversation fuelled by unstructured and unscheduled messages, and credits it with real virtues: it is simple, flexible, needs no training and works quickly in a very small group. It argues the workflow breaks down beyond a small group.
Newport (2021), Introduction. English wording confirmed from reader highlights, Goodreads, https://www.goodreads.com/notes/54902468-a-world-without-email/10400217-jaime ("A workflow centered around ongoing conversation fueled by unstructured and unscheduled messages"), and S. Smerilli, "A World Without Email - Book Summary and Notes", https://www.simonesmerilli.com/writing/a-world-without-email .
The introduction gives four figures: an estimate of 126 work emails sent and received per worker per day by 2019; a time-tracking company's finding that its users checked email or instant messaging about once every six minutes; a University of California, Irvine field study of forty employees over twelve days who checked their inboxes seventy seven times a day on average, one of them more than four hundred times; and a software company's survey putting work email at more than three hours a day.
Newport (2021), Introduction. Spanish reading sample (item 1): "en 2019 un trabajador medio envió y recibió 126 correos electrónicos de carácter profesional al día"; "una vez cada seis minutos"; "setenta y siete veces al día" for forty workers at a large company over twelve days, one more than four hundred; and an Adobe survey of more than three hours a day.
English wording of the first: Goodreads quotation page, https://www.goodreads.com/quotes/10779201-one-study-estimates-that-by-2019-the-average-worker-was ("One study estimates that by 2019 the average worker was sending and receiving 126 business emails per day").
Deep Work (2016) treated email as a distraction for individuals to manage; at the launch of A World Without Email Newport said he had naively assumed organizations would make time for focus once they understood its value.
Pressman, A. (2021, March 2). "Author Cal Newport on why we need a world without email." Fortune, https://fortune.com/2021/03/02/author-interview-cal-newport-book-world-without-email , in which Newport describes Deep Work as treating email as an individual distraction and says he "naively assumed" organizations would make room for focus.
Cal Newport is a full professor of computer science at Georgetown University whose research is the theory of distributed systems, especially what can and cannot be solved in difficult settings. He is a contributing writer at The New Yorker and has published eight books.
Cal Newport, "About", https://calnewport.com/about/ , giving full professor of computer science at Georgetown, the theory of distributed systems, a PhD from MIT, contributing writer at The New Yorker, and eight books including Slow Productivity, A World Without Email, Digital Minimalism and Deep Work.
Newport has described how theorists in his field study asynchrony in computer networks and found that removing real-time back and forth makes coordination harder and requires many more messages. The book carries the point into offices: something two people could settle in a short conversation can take a dozen emails.
Shortform, "Cal Newport on Email & the Problems With Instant Messages", https://www.shortform.com/blog/cal-newport-email/ , summarising the book's argument that asynchronous communication "requires many more messages to be exchanged" and its example of a meeting that takes two minutes to arrange in conversation and about a dozen messages by email. Smerilli (item 3) lists "the hidden costs of asynchrony" as a section of the book's third chapter.
The book was published in March 2021, runs to 320 pages, and is in two parts: the case against email (chapters titled, in substance, email reduces productivity, email makes us miserable, email has a mind of its own) and four principles (attention capital, process, protocol, specialization).
Penguin Random House, as in item 8: Portfolio, on sale 2 March 2021, 320 pages, ISBN 9780525536550.
Leslie Perlow of Harvard Business School describes a "cycle of responsiveness": a legitimate need for responsiveness raises colleagues' expectations, requests expand, pushing back risks looking less committed, and the cycle grows without anyone intending it. The book uses her term.
"Breaking the Smartphone Addiction" (2012, May 14). Harvard Business School Working Knowledge, https://www.library.hbs.edu/working-knowledge/breaking-the-smartphone-addiction , an interview with Perlow about Sleeping with Your Smartphone (Harvard Business Review Press, 2012): "Once colleagues experience this increased responsiveness, their own requests expand", and the cycle "grows (unintentionally) vicious".
The first published measure of the cost of switching between tasks is usually credited to Arthur Jersild in 1927: people alternating between two tasks were slower than people doing one task at a time.
Jersild, A. T. (1927). Mental set and shift. Archives of Psychology, 89, 5 to 82. No DOI (pre-DOI monograph series).
PsyToolkit, "Task switching", https://www.psytoolkit.org/library/taskswitching.html , which cites Jersild (1927) as the first report of the difficulty of rapid switching between tasks and describes the comparison.
Gloria Mark and Victor González, 2004, "Constant, Constant, Multi-tasking Craziness": fourteen analysts, developers and managers at one IT and accounting outsourcing firm, shadowed for 477 hours in total. People spent about eleven and a half minutes in one working sphere before switching, and were interrupted about twenty five times a day. Verbal interruptions (people arriving, phone calls) drove more switching than electronic notifications such as email alerts.
González, V. M., & Mark, G. (2004). "Constant, constant, multi-tasking craziness": Managing multiple working spheres. Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI 2004), 113 to 120. DOI: 10.1145/985692.985707 (confirmed via Crossref). Full text: https://www.ics.uci.edu/~gmark/CHI2004.pdf
Mark, Voida and Cardello, 2012: email was cut off for thirteen staff at a scientific research organization for five working days, compared with a baseline of a few days of normal use, with every window switch logged. Without email, people switched windows less often and stayed in each window longer. Heart rate variability pointed toward lower stress, but only seven participants provided usable data and the difference was not statistically significant.
Mark, G., Voida, S., & Cardello, A. (2012). "A pace not dictated by electrons": An empirical study of work without email. Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI '12), Austin, Texas. Honourable mention for best paper. Full text: https://onlabor.org/wp-content/uploads/2017/03/CHI202012.pdf ; record: https://isr.uci.edu/node/1330.html . *DOI not confirmed*: the commonly given 10.1145/2207676.2207754 could not be checked because the resolver was rate-limited; confirm before the episode page goes live.
Peter Drucker coined the term knowledge worker in 1959 and argued in the 1960s that knowledge workers cannot be closely supervised and must direct themselves. Newport argues that management took this as a reason not to examine how knowledge work moves, treating each worker as a black box, and that the hive mind filled the gap.
Newport (2021), Introduction and chapter 4. Spanish reading sample (item 1): Drucker's ideas led managers to treat knowledge workers as autonomous "cajas negras". Reader highlights (Goodreads, https://www.goodreads.com/notes/54902468-a-world-without-email/10400217-jaime?page=4 ) on Drucker's 1967 point that knowledge workers cannot be closely supervised and must direct themselves.
Shortform (item 9): Drucker "coined 'knowledge worker' in 1959" and argued these workers should control their own schedules. Drucker, P. F. (1959). Landmarks of Tomorrow. Harper; Drucker, P. F. (1967). The Effective Executive. Harper & Row.
The book says that before 1913, assembling a Model T took more than twelve hours of labour, and that once the cars moved past stationary workers it took about ninety three minutes. From that it builds the attention capital principle: the brain's capacity to focus is knowledge work's raw material, and the workflow is the arrangement around it.
Newport (2021), chapter 4. Patterson, D. (2021, April 21). Review of A World Without Email. The Gospel Coalition, https://www.thegospelcoalition.org/reviews/world-without-email-cal-newport/ , reporting the book's 12.5 hours and 93 minutes. Reader highlights (item 17) on Ford's 1913 move to bring the car to stationary workers and the cut "from over twelve hours to about ninety-three minutes".
The process principle: decide in advance how recurring work moves; use a task board with columns for stages and cards for tasks, keeping discussion of a task on its card; one marketing firm in the book gave each client its own board; and a short regular status meeting in which each person says what they did, what they are doing next and what is blocking them.
Shortform, "A World Without Email PDF Summary" (preview), https://www.shortform.com/pdf/a-world-without-email-pdf-cal-newport : task boards with stage columns and task cards, discussion on the card, short regular status meetings.
The six-minute figure is a time-tracking company's analysis of anonymised data from more than fifty thousand of its own users, and it is a median gap between check-ins.
MacKay, J. (2018, July 11). "Communication overload: Our research shows most workers can't go 6 minutes without checking email or IM." RescueTime blog, https://blog.rescuetime.com/communication-multitasking-switches/ : anonymised data from 50,000+ users, a "check in" defined as switching to a communication tool during other productive work, median time between check-ins about six minutes.
The three-hour figure comes from a software company's annual survey of about a thousand American workers estimating their own time on email.
"Here's how many hours American workers spend on email each day." CNBC, 22 September 2019, https://www.cnbc.com/2019/09/22/heres-how-many-hours-american-workers-spend-on-email-each-day.html : Adobe's annual email usage study, over 1,000 American workers, about 3.5 hours (209 minutes) a day on work email.
The seventy seven checks a day come from a peer-reviewed field study: Mark, Iqbal, Czerwinski and colleagues, CHI 2016. Forty workers in a research division of one large company, about twelve days each, with computer logging and chest-worn heart rate monitors. More time on email in an hour went with higher measured stress; more time on email in a day went with lower self-rated productivity.
Mark, G., Iqbal, S. T., Czerwinski, M., Johns, P., Sano, A., & Lutchyn, Y. (2016). Email duration, batching and self-interruption: Patterns of email use on productivity and stress. Proceedings of the 2016 CHI Conference on Human Factors in Computing Systems (CHI '16), San Jose, California. DOI: 10.1145/2858036.2858262 (as printed on the paper). Full text: https://www.microsoft.com/en-us/research/wp-content/uploads/2016/06/Email20Duration20Camera20Ready20submission3-1.pdf
Batching was tested in the same study: eleven of the forty were classed as batchers; batching had no significant effect on stress, and batchers rated their productivity higher than mixed-strategy users only at high email durations.
Mark et al. (2016), as in item 26: 11 batchers, 23 consistent checkers, 6 mixed; batchers defined as those whose three busiest email hours held at least half their email use; batching alone did not predict productivity; batchers rated productivity higher than mixed users at high email durations (interaction p ≤ .05); no significant effect of batching on stress, alone or in interaction.
Kushlev and Dunn, 2015: 124 adults in Vancouver, about two thirds students, spent one week asked to check email three times a day and one week with unlimited checking, in randomised order. Daily stress was lower in the limited week, about 1.46 against 1.55 on a scale from zero to four. In the limited week people checked about five times a day on average, against about twelve and a half in the unlimited week. The authors call the study exploratory and write that it is "by no means a panacea".
Kushlev, K., & Dunn, E. W. (2015). Checking email less frequently reduces stress. Computers in Human Behavior, 43, 220 to 228. DOI: 10.1016/j.chb.2014.11.005 (confirmed via Crossref and the publisher's resolver). Full text: https://www.interruptions.net/literature/Kushlev-ComputHumBehav15.pdf . University news release: https://psych.ubc.ca/news/checking-your-email-less-can-help-reduce-stress-new-study-by-phd-candidate-kostadin-kushlev/
Mark, Gudith and Klocke, 2008: forty eight people, mostly German students, role-played answering a set of work emails with interruptions every two minutes or none. Interrupted, they finished faster with no more errors, and reported more stress, frustration, time pressure and effort. The interrupted work lasted about twenty minutes, in a lab.
Mark, G., Gudith, D., & Klocke, U. (2008). The cost of interrupted work: More speed and stress. Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI '08), 107 to 110. DOI: 10.1145/1357054.1357072 (confirmed via Crossref). Full text: https://www.interruptions.net/literature/Mark-CHI08.pdf
The four principles rest on interviews, company cases and a survey of Newport's readers in autumn 2019 with more than 1,500 responses, and Newport describes the testimonies he quotes as anecdotal.
Newport (2021), chapter 1; Spanish reading sample (item 1): a reader survey in autumn 2019 with more than 1,500 responses, and the author's warning that these testimonies are anecdotal.
No study was found that recruited adults with ADHD and measured the cost of workplace or field interruptions.
PubMed searches on 2026-10-07: "(ADHD OR attention-deficit) AND (interruption[Title/Abstract] OR interruptions[Title/Abstract]) AND adult" (30 records, none on task interruption in ADHD; the hits concerned medication interruption, ageing and pain); "(ADHD[Title/Abstract]) AND ("task resumption" OR "resumption lag" OR "interrupted task" OR "prospective memory" interruption)" (one record: Altgassen, Koch & Kliegel, J Atten Disord 2019;23(1):51 to 56, DOI 10.1177/1087054713518236, eighteen adults with ADHD and eighteen controls on an event-based prospective memory task, which concerns remembering to interrupt a task, not the cost of being interrupted); "ADHD[Title/Abstract] AND (email[Title/Abstract] OR "e-mail"[Title/Abstract] OR notification[Title/Abstract] OR interruption[Title/Abstract]) AND (work[Title/Abstract] OR workplace[Title/Abstract] OR employee*[Title/Abstract] OR occupational[Title/Abstract])" (four records: a transgender adolescent cohort, pandemic medication access, a pediatric workload vignette study and a genetics meeting report; none on interruptions). A web search for interruption and resumption-lag studies with ADHD samples returned none.
Forster, Robertson, Jennings, Asherson and Lavie, 2014: seventeen adults with ADHD, diagnosed through a London adult ADHD clinic or support groups, and matched controls did a letter search; on one trial in ten an irrelevant, brightly coloured cartoon image appeared. It slowed the ADHD group significantly more than controls (p = .005). Raising perceptual load reduced the distractor's interference, as effectively for the ADHD group as for controls. Fifteen of the seventeen took stimulant medication and were tested after a twenty four hour washout.
Forster, S., Robertson, D. J., Jennings, A., Asherson, P., & Lavie, N. (2014). Plugging the attention deficit: Perceptual load counters increased distraction in ADHD. Neuropsychology, 28(1), 91 to 97. PMID: 24219607. PMCID: PMC3906797. DOI: 10.1037/neu0000020. Checked on PubMed 2026-10-07 (abstract: distractor interference greater in ADHD, p = .005, partial eta squared .231; load reduced interference as effectively in ADHD as in controls).
Kushlev, Proulx and Dunn, 2016: 221 undergraduates, not an ADHD sample, spent one week with phone alerts on and one week with them silenced, in random order. With alerts on, self-rated inattention and hyperactivity symptoms were higher; the differences were about a tenth of a point on a one-to-four scale. The authors state the findings do not show that notifications cause ADHD.
Kushlev, K., Proulx, J., & Dunn, E. W. (2016). "Silence your phones": Smartphone notifications increase inattention and hyperactivity symptoms. Proceedings of the 2016 CHI Conference on Human Factors in Computing Systems, 1011 to 1020. DOI: 10.1145/2858036.2858359 (confirmed via Crossref). Full text: https://www.interruptions.net/literature/Kushlev-CHI16.pdf
A field experiment across sixty six large firms and about seven thousand knowledge workers randomly gave some workers access to a generative AI assistant built into the software they used for email, documents and meetings, for six months. Workers who used it spent about two fewer hours a week on email, from a pre-period average of about 11.7 hours, and worked less outside regular hours. The study found no detectable change in the quantity or composition of workers' tasks. It is a working paper, and it was run by researchers at the company that makes the tool.
Dillon, E. W., Jaffe, S., Immorlica, N., & Stanton, C. T. (2025). Shifting work patterns with generative AI. arXiv:2504.11436 (v4, 13 November 2025), https://arxiv.org/abs/2504.11436v4 ; also NBER Working Paper 33795, https://www.nber.org/system/files/working_papers/w33795/w33795.pdf
Peopleware, by Tom DeMarco and Timothy Lister, was published in 1987; it argued that knowledge workers' offices were noisy and interruptive, treated the telephone as a source of interruption, and argued for doors and control over noise.
DeMarco, T., & Lister, T. (1987). Peopleware: Productive Projects and Teams. Dorset House. Review with page references: "RISE: Peopleware" (19 August 2013), https://bfwa.com/2013/08/19/rise-peopleware-productive-projects-and-teams-demarco-lister-1987 ("noisy, interruptive, unprivate, and sterile", p. 40; chapter 11, "The Telephone"; "Where there are sufficient doors, workers can control noise and interruptability", p. 75).