# Optimizing Workforce Productivity via Circadian Rhythms

**Podcast:** HBR IdeaCast
**Published:** 2026-04-07

## Transcript

On May 20th, join me at HBR's annual Leadership Summit with masterclasses, interviews with the CEOs of AT&T and Mattel, and an interactive case discussion led by Harvard Business School professor Kareem Lakhani.
This all-virtual day will give you practical frameworks to lead with purpose and strengthen culture across your organization.
To learn more, go to hbr.org slash leadershipsummit.
See you there.
I'm Alison Beard.
And I'm Adi Ignatius, and this is the HBR IdeaCast.
Adi, when do you do your best work?
You know, I generally have a lot of projects moving forward at once.
I'm tending to fires all day.
It's often at night after hours when I carve out time and do what's probably my best focused work.
I don't recommend this because it eats into my so-called real life, but I do find it necessary.
Okay, so it sounds like you and I might be the same.
I tend to sleep in, I wake up, I grab a coffee, and then I hit my stride mid-morning.
And I can work through the afternoon and also really, really late into the night if I need to.
So this means that you and I probably have similar circadian rhythms.
That's the internal clock that determines when we feel most awake and energized and engaged and when we don't.
And that's what we're going to talk about today.
Why leaders need to pay attention to their own rhythms and the rhythms of everyone on their teams to better manage and distribute work.
So I have to say, I've always been a little bit...
Skeptical about the circadian rhythm theory.
I mean, I've seen people talk about how we have these internal clocks and cycles and that they're real.
But I also suspect we can adapt.
In other words, that we have more control than you suggest about these rhythms and how they control our lives.
But I am not an expert.
Yes, well, our guest today is.
And he says that they're actually really hard to fight against.
And so you're better off trying to adapt within reason, of course.
And he has some really practical advice for leaders.
On how to organize around people's varying circadian peaks and ebbs to make sure that they're collaborating at mutual peaks and then splitting apart for their ebbs.
And this will all lead to better performance and well-being.
Stefan Volk is a professor at the University of Sydney Business School and author of the HBR article, Tapping Into Your Team's Circadian Rhythms.
Here's our conversation.
So let's start with the basics.
What exactly are circadian rhythms?
And how do they affect work productivity?
Well, we live on a planet that's rotating around the sun on a 24-hour cycle.
And over thousands of years, all living species on this planet have developed an internal timekeeping mechanism, which we call a circadian clock, that entrains us to specifically the light-dark cycle of our planet.
In 2017, the Nobel Prize in Medicine was given to the people who discovered the circadian clock.
And in humans, it is a little brain mechanism that sits over the eye nerves and it's very much related to our sleep and wake cycles whenever that little mechanism brain area recognizes darkness it uses hormones such as melatonin to make us sleepy and tired and when it recognizes light it floods our bloodstream with hormones that make us awake and energize and we all have these rhythms but they're significant differences in terms of when the peaks and troughs of these rhythms happen and that's what we call chronotypes and most people are probably aware of these terms of talking about morning people evening people intermediate people most children are morning types most teenagers are evening types and then from the age of 20 to 50 we become quite diverse people are morning types people are evening types and they say an extreme morning person extreme evening person could share bed with never sleep see each other because they have such opposed rhythms so people really do their best work are most energized at different times of day and that is currently not reflected at all in the workplace so we usually at least i said covid worked all very similar hours was traditionally the traditional nine-to-five approach and in addition there's a morning despise in many societies where there's often a belief that all the good things are happening in the morning yeah as a night owl i definitely dislike that morning bias and wish that everything would shift about five hours how much better are people at their circadian peak versus their circadian ebb in terms of their performance so the two aspects to it's it's the mental capacity and it's the emotional capacity right so when we are at our circadian peak we are more alert we are more attentive we have generally better cognitive processing capacities so we think clearer we are sharper we are better able to think clearer we are to respond to challenges we are better able to learn we can be challenged we can better deal with challenges while when we add our circadian trough then everything is slower it's harder we can still perform work but it's all a little bit essentially dulled and much more difficult it takes longer the other aspect how circadian rhythms affect us is through moods and emotions so when we are at our circadian trough we have reduced self-control we are more moody we are more impulsive and as a result we can be more impatient more irritable even more aggressive and also as leaders we are less effective because we just don't have the patience that we have when we are more emotionally stable at our circadian peaks why is it important for leaders to pay attention to not just their own circadian rhythm but also those of everyone else on their team what happens when they don't so in general most people are aware of their own circadian kind of predispositioning the problem with that is that we often assume that others are like us in particular people that are more morning types since they are more productive in the morning assume that most others are also more productive in the morning and that is obviously not the case right so knowing your team and knowing when your team have their peaks and troughs during the day obviously enables you to much better understand them understand why for example certain people in meetings are not contributing seem to be disengaged at a certain time it helps you to better understand why people sometimes might be a bit short-tempered why they might not be performing as usual and also when you can best leverage their strength and weaknesses during the day so for example the surgical team you know when you have two surgeons and you have a nurse in an operating room when they are all morning types and they are doing surgery in the evening that it's the worst time of the day where they would be least attentive and and most likely to be in the middle of the night and they would be in the middle of the night to make mistakes and errors so it makes sense to pay attention to people's peaks in particular when you have an ability to distribute work across the day to some extent and i can see that being true in sort of professional office settings as well where it seems less high stakes but at the same time you want people to be at their peak when they need to be collaborative and you need to schedule different types of work when people are at their ebbs or even give people a lot of time to break yeah so clearly we cannot always work around people's circadian rhythms that's in fact one of the most common criticisms i get about this type of research that people say what do you expect us that we now all work around people's individual preferences but that's not what we're saying we're saying is it makes sense to pay attention to this right and i do a lot of executive education where we talk about this and people then say they took it into their teams and they realize why that 9 a.m meeting on a monday morning doesn't work why it doesn't work so well i would imagine that when there are circadian mismatches there's also much greater conflict on teams when people are in particular when they are in their circadian trough it's similar to when we are tired when we are sleepy right so a major mechanism through which this works is self-control one way that keeps us from saying out loud what we think is an ability to realize that this is not the right thing the ability for self-control there's a brain connection between the brain area that produces strong emotions which is the amygdala and the brain area that controls these emotions which is the prefrontal cortex and that connection that essentially steps in and prevents us from being moody being impulsive is impaired when we are either tired sleepy or when we are at our circadian trough so as a leader we need to be aware that difficult conversations can be tricky when we are at the circadian trough because we are more likely to be impatient we are more likely to snap.
And similar for team members.
And that just can create a very negative kind of work environment.
What about the argument that people can change or shift their sort of natural preferences, that you can sort of train yourself to be a morning person?
Well, that's interesting.
I just had a journalist contact me from a finance newspaper saying he wanted to write an article about how to train yourself to get up at 5 a.m.
and love it.
And I said, so I'm really the wrong person for this because I'm really arguing against this.
The thing is that we know that the circadian system is a very slow, stable system.
And it changes very slowly.
So for example, I think over a 10-year period, it changes like around seven minutes during adulthood.
And you can see it, for example, when you travel.
Jet lag is nothing else but your circadian system trying to catch up with the new light-dark cycle.
And it can change.
You can only do this by one hour per time zone that you traveled.
So you may think you have adjusted quicker because you're already going to bed and waking up at the right time.
But it's a deep biological process.
All your organs, even down to the microbiota in your gut, they have a circadian rhythm.
And they have to adjust to this new kind of setting.
It's a very slow system.
And if we are in our natural setting, it won't change much.
And that's what happens a lot.
People try to get up earlier, but evening types cannot easily fall asleep earlier.
It's because their biology, their body doesn't settle down early.
Their melatonin production doesn't start early enough to initiate sleep, right?
So what then happens is that people that try to become morning people simply cut down on sleep.
And when you cut down on sleep, it has a whole range of other negative consequences in relation to your performance, in relation to your health, and in relation to your moods and emotions.
This is all music to my ears, because I am constantly told that I need to try to wake up earlier and that I should recover from jet lag more quickly.
And now you're giving me scientific evidence that I can't.
I can't.
So we are in an era when teams span time zones.
People can work from anywhere at any hour.
Does that make it easier for people to work at the right hours for them, you know, within their circadian rhythms?
Or is it harder because we're all constantly connected?
The only good thing that came out of COVID is that many organizations realized that flexible work arrangements are not as bad as they thought they would be.
However, if you look at it, you see that a lot of flexible work is actually about flex place, but not flex time.
So you still have to attend that 8am or 9am meeting.
So people are still essentially stuck in a very strict kind of time schedule.
And what we are suggesting is, and what many organizations are in fact already doing, is that you have some core working hours during which, everybody has to be available for meetings, for creativity, for teams to be able to coordinate, for example, from 10 to 3.
And then there should be hours where people can add to make up their full hours.
So for example, some people could add hours in the morning, some people could add hours in the evening.
So that type of flexibility, we suggest can kind of combine the needs of the organization, the needs of teams with individual preferences.
For people who aren't sure what natural rhythm is or what their chronotype is, how do you figure it out?
Well, the most simple way is when do you wake up on a weekend with an alarm clock, right?
So morning people wake up early, they are jumping out of bed at 5am and are fresh and sharp.
And I hate those people because I'm an evening person.
And it's my own experience of being an evening person that has essentially shaped my research in this area because all the important things happen in the morning, right?
Like it starts in school with exams and universities with exams, job interviews, presentations, important meetings all usually happen.
And during the first half of the day, when morning people are having an advantage because they're operating at full capacity, while evening people are at a disadvantage.
But in general, when you naturally wake up on a weekend is a good indication what kind of type you are.
Most people are aware of what they are.
The problem is more to understand what other people are.
And when you wake up on a weekend, you have to you can measure circadian rhythms and chronotypes and lab settings through biological indicators.
But the field that does research on this, which is chronobiology, they have developed questionnaires that have been validated based on these biological indicators.
And they're very easy to administer, they're freely available.
And what I suggest, for example, in my executive education is that people take these questionnaires, and they do them in their teams.
And they use this as a conversation starter that people firstly can reflect on their own results, and then they can reflect on their own results.
And then they can reflect on their own results, but also see what other people are, and then start a conversation around what does it actually mean for you, you know, in terms of work, in terms of performance, in terms of preferences, and what does it mean for us as a team?
How can we essentially try to work across these differences?
Or maybe we are all morning types, which would be then easier, but that is rarely the case.
So let's dig into some of the changes that one might make when they know their own circadian rhythm, and they know how that compares to other people.
So let's dig into some of the changes that one might make when they know their own circadian rhythm, and they know how that compares to other people.
So let's dig into some of the changes that one might make when they know their own circadian rhythm, and they know how that compares to the people on their team.
I guess the first step is sort of understanding and optimizing for your own rhythms.
What work should we all be aiming to do in our peaks, especially as leaders?
Different people have different preferences.
But basic rule is the thing that you really don't want to do that's really challenging for you, that's the one that you should really tackle during your peak time, because that's when you are mentally, emotionally at fullest capacity, we have maximum self-control, we have maximum It could be for some people having a conversation with a team member.
For others, that's something that they actually enjoy, to having that conversation with a team member, but they loathe doing the accounting or, I don't know, other things.
And then there are obviously many other tasks, more routine tasks, for example, often email.
There's a thing that they call the morning inbox problem, is that often, in particular, when you work with international teams, when you wake up and you come to the office in the morning, your email box is full.
And then people start working through these emails.
And a lot of this is just routine work.
And morning people, in particular, are wasting their best hours doing this type of routine work.
And then once they're done with the emails and they're going into the early afternoon, they go and do the more challenging work, like strategic planning, for example, or interactions with team members, meetings, and so on and so forth.
But then they have already wasted their best hours.
I do wonder, though, in terms of adjusting your own schedule to suit your circadian rhythm, there must be teams and organizations where just a specific type continues to be valued because that's a culture.
You know, so is it really possible to adjust on the margins in a way that will make you feel healthier if there is an expectation that there is always 7 a.m.
meetings or that there are always late night dinners?
It is, to a large extent, driven by the leader, right?
So we know, for example, that people like Arianna Huffington is a big supporter.
She's a big supporter of the healthy sleep and circadian alignment.
In other areas, like, for example, Donald Trump usually talks about how little he sleeps and how this helps him to be more competitive.
So the people at the top essentially set the tone.
But we have research that shows, for example, that leaders misjudge their employees.
For example, if your boss is a morning person and you're an evening person as a team member, you're more likely to get bad performance evaluations compared to a team member who's also a morning person.
A lot of this is around awareness.
My experience is that starting a conversation around this typically brings about positive change that people are more likely to recognize that there is value in allowing people to adjust to a certain degree.
So once leaders are aware of, you know, the different chronotypes and rhythms on their team, and they know sort of which type of work should be done when, either collaboratively or handing off, what's the best way for them to adjust to a certain degree?
To sort of instruct people or schedule people or encourage people to do the right thing here?
It depends on the size of the team, obviously, right?
But in general, if you know your team members, you know, you will know very quickly once you start a conversation, what types people are, right?
And then it really depends.
What is your own chronotype?
Are you a morning person?
Do you have a big job, a big presentation in the morning?
Do you need the support from a team member that is equally peaking?
At this time, right?
So who do you choose to go into that meeting with you to go into that presentation with you in order to support you in that presentation?
Similar if you have to do that presentation in the afternoon, right?
Where you are not at your best, you're not going to take the same person, you take the person where you know that person is more of a afternoon person and is sharper and, you know, stronger at this point of time.
Sometimes you need somebody to support you at peak time.
Sometimes you want to support somebody at peak time.
Sometimes you want to take yourself out as well.
So for example, in the afternoon as a morning person, that's a good time to take yourself back a little bit, not essentially drive every single decision, everything, single process.
This is a good time to empower people to delegate work to other people that are more energized during that time, you know?
So when do you take charge?
When do you let go?
You know, when do you delegate?
When do you step in?
In particular, outside of your circadian peak time, have to conserve the limited energy you have for the really important situations where you have to step in.
But obviously, you can already at the beginning of the day, start to plan your day tasks around these things in terms of when do we do the more challenging work?
When do we do the more routine work?
And how can we distribute it across the team?
The beauty of the team is that you can really leverage these differences and coordinate them in a very productive way as much as possible.
Sometimes morning people and evening people have to work together.
And then there's often also a middle ground where you work in the middle.
So for example, I know my supervisor was a morning person, I was an evening person.
So we used to have our meetings around noon when he was still mentally alert, and I was already mentally alert.
So we found a bit of a middle ground there, right?
The same probably goes for team meetings and collaborative work, you know, brainstorming or, you know, anything where you need, as many people at their peak as possible, you just need to find that common ground time that will be best for everyone, right?
For most people being engaged, yes.
And at the fringes of the day in the early morning, in the late evening, you're more likely to lose a substantial fraction of your team.
So they say around 20% of people are morning people, around 20% are evening people.
But it's actually a continuous variable.
People can peak at any point during the day, right?
So, it's quite distributed, but, you know, it's a bit of a normal distribution where most people are more in the middle of the day.
So scheduling late morning would be a good time because we also know that in the early afternoon, there's a little dip in our circadian rhythm.
That's what you feel when you're really tired in the early afternoon.
Often people think it's a high carb lunch, but it's probably less the lunch.
It's more that we have a predisposition to nap.
We have an evolved predisposition to nap.
And it's a little bit of a dip in our circadian rhythm.
So, you know, you can still see it in the circadian rhythm.
So there's a little dip in the early afternoon.
And that is usually the worst time to have meetings.
And as a boss, when you need to ask people to work outside their peak time, how should you communicate that and make sure that they're going to give it their all, you know, even though they're not at their best?
So people are used to do that, right?
Because that's been the standard.
So people are just being asked to work at times.
And whenever it suited the organization, the team, not so much when it was in their own preference.
So people probably won't complain about it.
But it is good to be aware that they can still function, right?
But everything takes longer.
Everything is harder.
They're depleting quicker, right?
So if you do this constantly, people are much quicker burning out or developing other health problems.
So we have to account for this.
We have to allow for recovery.
We have to rotate people out of these patterns.
People have to be aware that.
And in fact, we are mostly not aware of this, that when we are outside of our circadian peak, our attention, our reaction time, all these things are slowed and subdued.
Happens also for me very often when it gets too late and I want to finish some work before I go to bed, just I want to finish the project.
And a job that would take 10 minutes usually takes me an hour and then it's not even well done.
So we have to be aware.
We have to have the second set of eyes.
We have to be aware of that.
And then we have to be aware of that.
We have to have more checks and balances and we have to give people more ability to recover and recharge.
And then we can also obviously work outside of our rhythms for a certain time.
Is there an example of a team or organization that you've seen implement these changes and team performance has demonstrably increased as a result?
So in the article, we have a couple of examples.
For example, there's Think2See of Rivago, who is a morning person and has realized that this is precious time for him.
And he essentially blocks that morning time for his own work, essentially.
So he doesn't have any meetings in the morning in order to be able to do the tasks that he perceives as most challenging during that time.
We have an example of Citigroup that has different teams working at different times, depending on their ability in cross-border transactions, where they, also, could see an improvement in performance, improvement of happiness of the employee.
It is something that is still relatively new, though, right?
So that's why we talk about it.
It's what most organizations are not aware of.
Again, we have industries where this has been implemented for a long time, where it's very clear evidence that it's related to reduced errors, reduced mistakes in aviation, in transportation, where this has been done for decades.
But it often is seen as it's only relevant, if you go to the extremes.
For example, night shift work, right?
But it's not just about night shift versus day shift.
Within a day, within a regular 10 to 8-hour day, there are quite significant differences in terms of people's ability to perform.
And adjusting to this can have very positive effects in terms of performance, in terms of well-being, and in terms of long-term health.
Terrific.
Well, Stefan, this, as I said, has been a conversation that is music to my ears, because...
I definitely work best at night, and I want to keep doing it.
And so I am now not going to wake up at the crack of dawn to try to be more productive.
And I'm going to encourage everyone on my team to follow their own circadian rhythms as well.
So thank you so much.
It's been a pleasure talking to you.
Yes, thank you.
Thanks for having me.
That's Stefan Volk, professor of management at the University of Sydney Business School and author of the HBR article, Tapping Into Your Team's Circadian Rhythms.
Next week, Adi speaks with Marcus Buckingham about the importance of customers truly loving your products.
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