Ep 163 Circadian Rhythm: Live from Perth, Australia

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Good morning, Aaron.

Good morning, everyone, and thank you for the invitation to come and share a story that I went through in my career.

In 2012, I was an intern back in Dublin in a large teaching hospital.

It was six months after finishing my intern year, aged 23.

And I was working in a busy surgical unit.

It was January, and I was woken up at about 6 a.m.

to go and start my journey to work.

As I've gone to work,

bear in mind it's a Thursday.

I've already undertaken about 36 hours of work within this work week from Monday, and I'm about to go and start on another Thursday.

I feel I'm relatively well rested, but I know that I'm not feeling particularly good going in to start a very large shift, which I'm going to elaborate on a little bit now.

At 6:30, I arrive into work and I undertake results checking.

We look at all the results of our patients from the day before, recent blood tests, recent scan results, and ultimately to prepare for the ward round when our surgeons, the consultants and the senior doctors, will start undertaking looking at every patient on their list.

At seven o'clock we start sharp and we finish about eight o'clock.

And at eight o'clock those senior surgeons will head off to surgery and us as the junior doctors will then undertake the tasks of the day.

We'll look at organising consultations, we'll be writing letters, discharging patients, admitting new ones and then deal with problems as they occur on the wards.

It's fast-paced, it's a busy unit, but it's something that I thrive.

I enjoy the challenges as they present.

I really am passionate about the work and I'm very happy to work in such a busy environment, even though you might only be getting 20 minutes for a quick lunch break.

You feel very valued, you feel wanted and a key cog in that machine of the hospital.

But there's very much a drive, you have to have the work done, and it has to be done correctly, it's got to be done with precision because at the end of the day, patient care depends on it.

As the day continues,

we take over to about quarter to six in the evening.

And then the surgeons are starting to come out of theatre, and then we start doing a further round through the hospital again of all the patients that have been under the lists of the surgeons whom I've operated and those who are still waiting waiting after their operations.

These rounds then can finish about quarter past seven.

So bear in mind, I've been in the hospital since 6:30 and it's now quarter past seven at night.

I then start the next part of my shift.

And back in 2012, we were routinely rostered to do 24 hours.

So I will then move from my day job to then providing night cover in the tertiary hospital.

of which there are only four interns.

All of us have only done six months prior and we're all fresh out of college, maybe 23, 24, 25.

We each cover in the region about 180 patients each with one senior doctor to call upon for assistance as we go through the night.

Now usually you would get a scattering of sleep here or there of a few hours and maybe hold each other's pagers.

This particular night in question,

that was not going to be one of those cases.

We

were dealing with sick patients across the hospital and in my particular area that I was looking after.

I know offhand that I was dealing with a patient who was having an acute stroke on the middle of the ward, as well as a patient who was bleeding post-operatively on the ward and trying to get them back to theatre for emergency surgery.

Jobs kept creeping up as we went through the night and they did not stop.

But then we were getting to 6.30 in the morning and I was then starting to get set for the next ward round which my team were getting prepared for.

And it's at that point that I've been notified that we have a sick doctor on and I'm going to be required to stay.

And my boss has asked me to stay and conduct surgery with him.

Now, bear in mind, I'm not a surgeon, and I'm working under complete supervision of very senior surgeons at the time.

I'm not putting any patient within risk because I'm simply holding a retractor.

I'm not doing anything that's going to be compromising them.

It is simply to be able to hold something in theater and provide that extra bit of support so the surgeon and their assistant can do their work under full supervision at that time.

I finish and I'm wrapped up about 11.30 in the morning and excuse, at which point I've probably been awake for about 29 hours and scatterings of sleep here or there.

I make the decision to drive home and nobody forced me to make this decision.

I took that completely on myself.

And as I'm driving down the Grand Canal in Dublin, I fall asleep at the wheel.

and I wake up with a jolt and I've put my car into the back of a large Dublin bus.

I get out of the car, looking at the smashed windscreen, completely obliterated bonnet and smoke coming off the engine and I'm shaking.

I'm uninjured but really fraught with anxiety and just fear of what's happened.

I call my dad who's been a fantastic wealth of

wealth of advice and support for me over the years who helps me to navigate the situation in relation to getting insurance, calling retrieval authorities, etc., to get the cars off the road.

He slowly makes his way to come and see me on the Grand Canal dock and as traffic starts to move on, we get the daggered looks of the frustrated drivers whose days have been interrupted by

my accident.

What my dad has said had been a wealth of advice over the years says to me is that this has been a very valuable learning curve for you and you've gone through it without anybody being injured and for me that was what was really interesting was because now as I reflect back on that, my life could have taken a very different turn.

Not only was I uninjured, but I did not injure anybody else.

And it's something that it really does strike fear in me that I didn't only put myself in a position of danger, but I put others in danger.

And it only cost me the price of my car, not the cost of someone's life or my own life.

And leaving a family, potentially having an injured family member, or even my own family, where they would have to deal with my death because of the decision I made.

But in reality, I was far too fatigued to make that decision correctly.

And as I said, no one forced me to do this.

This was something that I did on my own bat.

And it's something I reflect on every day as I go to work, whether I'm making sure that I am not in a position where I can make an error like that again.

That is just a terrifying and very relatable story.

And I'm glad that you were okay.

I'm glad everything turned out okay.

And just thank you very much for sharing this story with us.

Yeah, thank you.

We're so glad, like you said, that the accident wasn't worse than it was.

And we really appreciate you sharing it with everybody here today.

I think it's something that unfortunately a lot of us can probably relate to.

So thank you so much.

Thank you for having me.

Thank you all.

Hi, I'm Erin Welsh.

And I'm Erin Alman Updy.

And this is this podcast will kill you.

And we are coming to you live with our very first recorded live episode from Perth, Australia, the lovely Perth.

And we're here at the 2024 AIOH Annual Scientific Conference and Exhibition.

And we are just thrilled to be here.

We really are.

Thank you all so much for having us.

A huge thank you to Zach and Kelly and David and everybody who helped organize this conference.

We are truly honored to be up here today speaking with you all.

Really?

And in light of the fact that we are at the annual meeting of the Australian Institute of Occupational Hygienists, and we just flew across one million time zones to get here, not an exaggeration,

we decided to focus on a topic that is of central importance to pretty much every industry, and that is fatigue.

Specifically, fatigue caused by disruption in our circadian rhythms in the context of shift work.

And because that alone is such a huge topic that there's no way that we could fit it all into a 90-minute plenary, we're not going to make you sit here for 100 hours.

Don't worry.

We're going to take you through just a few parts of that.

So, first, I'm going to focus on what do we mean by fatigue?

How do we define that and what does that actually mean?

How our circadian rhythms actually work, and how disruption in circadian rhythms can lead to symptoms like fatigue, excessive daytime sleepiness, and so many other chronic health conditions.

And then I'll get into how our understanding of circadian rhythms has evolved over time, the changes that led to shift work becoming as widespread as it is today, and how we came to recognize those negative effects of shift work.

And then we're going to bring on a subject matter expert, Dr.

Ian Dunikin, who will share some of the current exciting research that's going on on circadian rhythms and how to combat the negative effects of things like shift work and jet lag.

Yes.

But first,

no episode of our podcast, This Podcast Will Kill You, would be complete without a beverage that we call a quarantine-y, or in our case, a placebarita, because we don't have any alcoholic spirits in it.

Nope.

But we are drinking one today.

Erin, what are we drinking today?

We're drinking TikTok, you don't stop.

Get it?

Because it's like a clock.

Yeah.

It'll be funny if we

explain jokes so that they're not funny anymore.

But what is in TikTok?

You don't stop here.

It's a delicious beverage consisting of one ingredient, which is Australian ginger beer.

So, thank you.

Thank you.

It's delicious.

And also easily modified.

You can add whatever spirit you would like, or just leave it with a little bit of lime in there.

Delicious.

Yeah.

Sorry, we should have really had the foresight to make a drink for everyone, like under your seats, you can find.

Oh my gosh.

That would have been really Oprah of us.

Cheers.

Cheers.

To you all.

Okay.

Now, drinks are drunk.

Shall we?

We'll get into the biology of our circadian rhythms.

I can't wait.

Yeah, tell me all about it.

It's going to be fun.

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So we decided to do this talk today on fatigue because it's kind of this universal experience that also happens to be an occupational hazard in so many different industries.

Everyone has at some point been fatigued, experienced fatigue.

But when we talk about this idea, what do we actually mean?

Like, how do we define fatigue?

Right, it's super easy to define.

Yeah, right.

There's not a definition.

There is not a single definition of fatigue, but there are a lot of different definitions.

Most of them use a lot of synonyms, things like tiredness or exhaustion.

Most of the definitions include something like the decreased ability to function at your normal capacity or some kind of decreased capacity for mental or physical work.

Okay.

So overall, we're looking at fatigue as this generalized lack of energy that overall has some kind of impairment on your ability to function, be that your physical function or your cognitive function.

All right.

Make sense?

Okay, I'm following.

But in that definition, what's important about it is that we then have to intentionally separate fatigue from sleepiness.

Right.

Right.

And how does one do that?

How does one do that?

By defining sleepiness.

Okay, more definitions.

More definitions.

So we can do this by defining sleepiness as directly related to the physiologic phenomenon that is the act of falling asleep.

Okay.

Because that means that it's something that we can measure, okay?

At least to a better degree than we can fatigue, which is so nebulous.

Right.

And we do this, we can measure sleepiness with a couple of different tests.

There's one called the multiple sleep latency test which is i'm going to put you in a dark room and you're going to lay down and fall asleep how long does it take you wow sounds not stressful at all right no

and then there's also the maintenance of wakefulness test which is how long can you stay awake if we sit you in a dark room and ask you to not sleep sit you have to be sitting just sitting okay with your thoughts in a dark room no i don't like that idea

now sleepiness itself like falling asleep it's not a bad thing inherently we have to sleep.

It is required of all humans.

And as humans are diurnal species, we have evolved to sleep at night when it is dark and be awake when it is light.

So being sleepy at nighttime itself is not a bad thing.

But if that sleepiness is happening when we shouldn't be asleep, then it can lead to what's called excessive daytime sleepiness or this inability to stay awake during hours when you should be awake.

And that can be bad, or as we heard in our firsthand account, even downright dangerous.

Both excessive sleepiness and fatigue, though they are different and these definitions are important, they're also kind of two halves of a story, and they both contribute to the kinds of accidents and workplace events like we heard about in our first-hand account.

And while circadian rhythm disruptions themselves are by no means the only things that can cause excessive daytime sleepiness or fatigue, These are two of the most immediate consequences that we see from circadian dysfunction.

So having a basic understanding of what our circadian rhythms are and how they work can go a really long way to understanding what happens if they get pushed out of sync, which then can lead us to better anticipate the hazards that might be inherent to some professions or recognize these symptoms when they start to crop up during certain phases of life.

Hello, newborns.

Gotta love them.

And then evaluating and understanding these consequences of this type of circadian disruption can help us to actually implement strategies in the future to help mitigate some of these.

Hopefully, we'll get there.

Yeah, can it be done?

Can it?

So then, first we have to start with what really is circadian rhythm.

And I think most people probably have a sense of what this means in their mind, right?

It comes from the Latin circa means about and dies or diem means day.

Stole my line.

Thank you.

So when we talk about a circadian rhythm, we're talking about cycles that are happening in our bodies on an about 24-hour timeframe.

And Erin, I know later you're going to talk about why we have these rhythms.

Yeah.

Like from an evolutionary perspective.

Yep.

What are they doing for us?

They're important.

Are they?

Let's find out.

Yeah.

But I'm going to focus first on how they actually work.

And everyone is probably most familiar with a circadian rhythm in the context of sleep and our sleep-wake cycle.

Because our sleep-wake cycle is one of the most classic examples of our circadian rhythm in action.

So we can see a few different things that oscillate in our sleep-wake cycles.

One of them is something like melatonin secretion.

So our melatonin peaks in the couple of hours before we go to sleep and then we'll go to sleep.

Our cortisol levels will peak in the morning right about the time that we tend to wake up.

We also see oscillations in our body temperature with the lowest body temperature happening in the wee hours of the night while you're still asleep.

I just want to ask why for each one of these.

I don't have great answers, but I can tell you that what these, like the why is that these processes together are what are driving our drive for wakefulness

and our pressure for sleep.

Okay.

So these three things, they're not the only things that are involved in what's literally keeping us awake during the day and telling our bodies we need to go to sleep at night.

But these are three of the big drivers of that drive for wakefulness that happens during the day and that pressure for sleep that happens through like towards the night.

But what's the deal with temperature?

Oh, I don't know, Erin.

And also, what is that?

So the body temperature changes by how many degrees?

I knew you were gonna ask that and I meant to like look it up again to try and get a, I don't know.

I don't know that.

20.

It's just a few.

Yes.

Like a...

proportions of a degree.

Yeah, yeah, yeah, yeah, okay.

Or little changes.

But it's enough that it's sort of in that period when we're close to waking up, that drop in temperature is what helps our body stay asleep, essentially, right?

It's colder, stay asleep, etc.

Right?

Okay, all right, explain why I don't sleep well when I have that.

Yeah, we're going off track.

Yep.

So, as humans, because we're diurnal, we see these particular cycles again on this 24-hour clock where sleep is happening at dark and awake time is happening during the light.

So, this is what we all think of when we think of circadian rhythm.

But it is not just this.

Our circadian rhythm, like literally every single function and process in our bodies from the cellular level, like the genes that are controlling which cells are gonna divide when, the genes that are controlling DNA repair, does it happen in what cells and when, things like our immune system, our metabolism, our hunger cues, our bowel movements, our libidos.

Every function in our body is controlled to one degree or another by circadian processes.

It's like the ultimate, but wait, there's more.

It's not not just sleep, wake, it's everything.

Everything.

And these all are our circadian rhythms.

It's not just sleep, but sleep is a big part of our circadian rhythm.

And these circadian rhythms are mechanized internally in our bodies by what's called an intrinsic circadian clock.

But not just one clock.

We have multiple clocks.

We have a main clock in the part of our brain that's called the suprachiasmatic nucleus.

I'm really glad that you pronounced this because I just wrote SCN over and over again.

I don't even know if I talk about SCN, but no.

Now I know how to pronounce it.

The SCN or the suprachiasmatic nucleus.

And this region in our brain functions as like a master regulator of our internal clock.

But all of our peripheral cells and tissues, they all have clocks of their own.

And together, all these clocks drive our many, many circadian rhythms in large part by the buildup and then the breakdown of specific proteins whose literal job it is to be made, build up, and then break down on a 24-hour cycle to keep these clocks all in sync with each other.

Okay.

Does that make sense?

Yeah.

It's like pretty basic, right?

Yeah.

Super simple.

I'm sure it took no time at all to figure that out.

No, no, no.

So that's how these circadian clocks are working on like a cellular level.

And I said that these are intrinsic.

And we know that these are intrinsic because these cycles cycles will persist on an about 24 hour basis.

In humans, it's a little long.

We tend to run about 24 hours and 10 minutes.

I got 11 in here, 11 minutes?

11 minutes, 9 to 11 is what the literature says.

We can have a range.

Anywhere from 9 to 11 minutes.

And our clocks.

And 24 hours.

And 24 hours.

And 11 minutes.

9 to 11.

And our clocks keep doing this even if we put someone in a dark room with absolutely no external environmental excuse.

Like in in absence of the environment, our clocks still run.

However,

these environmental cues are in fact an essential part of our circadian rhythm.

Because a lot like clocks, old tiny clocks, not newfangled watches, which work by magic is how my eye watch works.

Yeah.

Okay.

Old tiny clocks, mechanical ones, you used to have to wind in order for them to keep correct time.

Our circadian clocks also have to be wound in order to keep them on as close to a 24-hour cycle as possible.

And this happens through a process called entrainment.

And the environmental cues that we use for entrainment in our circadian clocks are called Zeitgebers, which is my attempt at German.

And that is German for time giver.

How'd she do?

Did anyone speak German?

Not great, I can tell.

I tried really hard.

Zeitgebers.

In humans, it is light, predominantly light from the sun that acts as our number one zeitge or time giver.

And the sun, light from the sun, is detected by these specialized cells in the back of our eyeballs that project directly to that SCN, the suprachiasmatic nucleus.

And that part of our brain, again, is this pacemaker that coordinates the cycles in all of the rest of our body.

And they do this, they coordinate the timing of like so many different processes, right?

Through direct and indirect pathways to keep us on this 24-hour cycle in sync with the sun or the light around us.

Now, light is by no means our only zeitgeer.

Food can be a powerful one, especially for other mammals other than humans.

We also can see exercise, social activity, other things can serve as zeitgeers.

But light is by far the primary one that our particular clocks use, which means that although these rhythms are generated internally, they do require entrainment, mostly via light, in order for so many of our biological processes to match our environment.

So when our environment changes, like when we travel across exactly nine time zones, I counted between California and Western Australia to come to a conference.

10 for me.

Suffice to say, our internal clock no longer matches our external environment.

I'm feeling okay, though, I will say.

Thank you, caffeine.

Yeah, that's a big part of it.

Right.

And we all know this particular phenomenon very well.

This is jet lag.

And with jet lag, because of this discrepancy between your external environment, the timing of light exposure, and where your internal circadian clock was set before you left, you end up feeling pretty terrible.

Right?

I'm not, not myself.

Not today, right now.

We feel great.

But you can end up feeling pretty terrible.

You might have symptoms like a really hard time falling asleep when it's time to fall asleep.

Or maybe you simply cannot keep your eyes open for like an afternoon meeting when you get to where you're going.

And because, again, this maladjusted timing is affecting every body system that we have, not just sleep, it's not just being fatigued or being excessively sleepy.

You might also have GI upset, mood changes, brain fog, and so much more.

Now, in addition to regular old jet lag, there's also a phenomenon called social jet lag.

We'll separate it.

All right.

And social jet lag is basically this idea that we all, as like a society at large, not us in this room here, we have all decided that our day starts at like 8 a.m., right?

Or whatever.

Yeah, we can say.

And that is when the day is supposed to start for everyone across the board.

But a lot of us maybe end up relying on like our alarm clocks to wake us up on the weekdays to be able to get ready for work on time.

A lot of us.

A lot of us.

Who doesn't?

That would be

amazing.

Yeah.

And then when that happens, many of us might perhaps on weekends, when our schedule permits it, sleep in later, go to bed later, stay up later.

So we have this shift in what our schedule looks like between weekdays and weekends.

And it turns out that different people might feel differently.

Some of you might be like, oh yeah, I do that.

And others are like, nah, dude, 6 a.m.

I'm ready to go.

That's because we all have different chronotypes.

And a chronotype is like different natural tendencies to either sleep early or sleep late, like early bird, night owl.

It's a real thing.

Which are you?

I'm an early bird.

You're an early bird.

Very early.

And like, so what is the threshold?

Oh, what a fun question.

Yeah.

I don't know.

I don't know.

Okay.

I don't know if there's like a specific thing.

And can you be neither or can you be like a light early bird?

You can be neither.

You can be whatever you want to be.

Okay.

Are you an early bird or any bird?

I think I'm a mild early bird.

A mild early bird.

Yeah.

Like a not too early

bird.

Yeah.

I don't want the first worm.

No, I want like the second or third.

Floods are still left at the buffet.

I don't want them all gone.

I love that.

I'm an early.

Like that's very early?

No, no, probably not.

Okay.

That's being maybe I wish I was that early.

Yeah.

It's too much.

But for people, especially who veer more night owl,

then they might have an especially hard time waking up for that 8 a.m.

start every day, right?

This is especially true for teenagers, and that's not just a stereotype.

Teenagers actually, we see shifts in their intrinsic circadian clocks during the teen years.

And like most teenagers, at least in the U.S., start their days at like before seven.

Right.

Which is forced them to do it.

It was miserable.

It wasn't my idea.

And so this system of forcing these early wakings on some days and then maybe seeing a shift in what your patterns are like on the weekends, it can end up causing chronic sleep deprivation.

And so that's what we see in this phenomenon of social jet lag.

And that's something that a lot of us have probably experienced to one degree or another.

But we also then have even more severe or persistent disruptions in our circadian cycle that can result from a more chronic forced mismatch between our environmental cues and our intrinsic clocks.

And this is what we can see in shift work.

So across the globe, it's estimated that anywhere between 10 and 30% of all adults in industrialized countries, which is a lot,

work in shift work.

And often, if you work in shift work, then you might end up working outside of a traditional eight to five of like a regular old job.

And that might mean you're working night shifts.

And night shifts, of course, are going to require a complete flip of your circadian cycle where you have to adapt to working entirely during the dark hours and being asleep during the light hours, right?

But it might not just be night shift.

It can also mean rotating shifts.

Right.

It can mean late afternoon shifts that bleed into nighttime.

Or it can mean early, early morning shifts that require you to start your day before the dawn.

My mom was an afternoon night shift worker or an afternoon worker as a nurse, but she loved it because she would just lay out at the pool until 3 p.m.

Oh my God, that's hot.

That's what she said.

She was like, I loved it.

And then I would go home and have a look at that.

Is she a night owl?

Not anymore.

She's 7.30.

Because that would track.

But so all of these scenarios, any of these scenarios can serve to end up disrupting our circadian clock because they're disrupting the typical timing of our light-dark exposure.

In a lot of cases, it might be exposing our eyes and thus our brains to light essentially 24 hours a day.

And while sometimes people can adjust the timing of when they're asleep and when they're awake, like maybe they sleep just fine during the day, lay like sleeping in late and then laying out in the sun or whatever, what we do see is that the vast majority of shift workers do not show a complete shift in all of their circadian rhythms.

Meaning things like their melatonin secretion, as an example, will still happen at nighttime.

And in some cases, can be up to 12 hours out of phase from when they're actually sleeping.

Wow.

Right?

Yeah.

There was one paper I read that estimated that only about 25% of people who work night shift long term actually show evidence of having a lot of these circadian rhythms actually being shifted in line with their real life.

Wow.

Right?

It's a pretty low percentage.

Okay.

And this is like continuous night shift work, not like rotating shift work or like two weeks on, two weeks off.

Exactly.

This was in people who were like night shift for the long term.

Yeah, yeah.

And so this can, unsurprisingly, result in what's called shift work disorder,

which is a disorder that can be characterized by things like insomnia, which is difficulty falling asleep or staying asleep.

Or it might be excessive sleepiness, like falling asleep when you shouldn't be at work or micro-napping.

But it can also lead to increased irritability.

It can lead to mood changes like depression or anxiety.

And it overall can lead to this mental fog that can lead to increases in mistakes because of all of this fatigue and sleepiness.

So some studies suggest that working during the night alone increases the risk of workplace accidents by 40 to 100%.

Whoa.

Which is huge.

It's a huge range also, but it's also huge, like very significant.

And shift work disorder alone is not that uncommon.

Some papers estimate up to 27% of shift workers meet the formal definition of shift work,

shift work disorder.

Okay.

But on a practical level, everyone who has worked shift work has probably experienced to one degree or another this negative effects of this circadian disruption.

Yeah.

But again, it's not just fatigue and sleepiness at work or outside of work, because especially what we see with time spent working night shifts having really significant impacts on long-term health.

Shift workers are at about a 20 to 35% increased risk of breast cancer, prostate cancer, colorectal cancers, but also type 2 diabetes, coronary artery disease, and depression, and many other chronic health conditions as well.

Eric, but like, what is the mechanism for that?

Like, why?

What do we know about that?

We don't know everything,

which is

a classic line.

And I will say that there has in the literature been some like pushback as to like how causal is this relationship because a lot of these disorders also have a lot of other lifestyle factors that influence them as well.

And so sometimes you might see difference in lifestyle between people who work shift work or night shift work specifically compared to day shift workers and things like that.

But the evidence, especially for cancers in animal studies, is so significant that

circadian rhythm disruption in animal studies leads to cancer formation, tumor growth.

And it is such overwhelming evidence that the International Agency for Research on Cancer named night shift work a probable carcinogen all the way back in 2007.

Wow.

This is like new information.

No.

But then if we dig even deeper on like, what is the mechanisms, we know that our circadian rhythms are affecting so much of our overall body functions.

And what we see is that dyssynchrony of our sleep-wake cycles and our endogenous circadian rhythms ends up leading to things like increases in blood pressure, reduced insulin sensitivity, elevated lipid concentrations.

And so, all of these might put us at risk for things like diabetes, hypertension, cardiovascular disease.

There's also some evidence between like timing of and amount of melatonin secretion and the effects on oncogenesis or cancer formation.

That's interesting.

Exactly.

So, at like a basic level, what it's thought to be is that all of these increases in risk are a result of the fact that that so many of us working night shifts, our endogenous circadian rhythms do not adapt to this forced pattern of being awake at night and being asleep during the day.

So it's a mismatch between our internal cycles and the environment.

So that's the best answer I've got.

I mean, I think that's a pretty good answer.

There's a lot of moving parts.

It is.

Yeah.

And probably a lot of specific mechanisms that go into each of the different

disorders and things like that.

But on the whole, I think I've convinced you all that it's abundantly clear that our circadian rhythms are very, very integral, not just in our sleeping and our weakness and our alertness or fatigue, but also in so much of our health.

So circadian rhythms are an important thing to consider in the context of a lot of our stages of life, a lot of our professions.

So I have a question for you, Aaron.

Uh-huh.

Ask.

Go ahead.

If this thing, these things, these circadian rhythms,

that seem today to be, it's so easy for us to disrupt them, to get them messed up.

You just hop on a plane, just change your clocks back, just go into a grocery store at night, right?

If it's so easy for them to get disrupted, and when they get disrupted, they can cause so much trouble.

Why do we have them?

What do they do for us as humans or creatures?

Like,

and when did we, how did we know all of this?

Tell me everything.

Okay, I'll tell you as much as I can tell you.

Maybe not everything.

Hi, I'm Morgan Sung, host of Close All Tabs from KQED, where every week we reveal how the online world collides with everyday life.

There was the six-foot cartoon otter who came out from behind a curtain.

It actually really matters that driverless cars are going to mess up in ways that humans wouldn't.

Should I be telling this thing all about my love life?

I think we will see a Twitch stream or president maybe within our lifetimes.

You can find Close All Tabs wherever you listen to podcasts.

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Wherever you are, whether you're here in this room in Perth, Australia at this conference, or you're tuning in from across the world, I want you to imagine yourself as a dot on the globe, as a pin on the map.

I've marked Perth here.

Now, let's rewind time.

Let's say 200 million years or so, keeping that pin in its original coordinates.

And I want you to picture a time lapse of the continents shifting, colliding, separating, oceans expanding and shrinking, mountains forming and crumbling.

What is your pin witnessing in all of this?

Has it mostly been adrift in a vast ocean?

Or has it been at the center of continental action, witnessed to collisions and separations?

Or maybe your pin has seen it all.

As our time lapse comes to an end, eventually, and the continents have settled into their familiar positions, Let's take a minute to marvel at the incredible dynamic changes that our planet has seen over those 200 million years, which is just a fraction of the Earth's four and a half billion year existence.

Grasslands turned to deserts, rainforests turned to freshwater lakes, and temperature, rainfall, and atmospheric composition shifting tremendously over these millennia.

Life on Earth has had to deal with a lot of change, even just over those 200 million years.

But throughout those transformations, there has remained one near constant.

The sun always rises and the sun always sets.

I love that.

It's so profound.

And while the time between sunrise and sunset varies across latitudes and seasons, the existence of a day has always been a feature of life on Earth.

So let's go back to your pin in the map, the 200 million years ago.

The day you'd experience, outside of like having to fight and hide from dinosaurs, is nearly identical to the one that you'll experience today.

Just about an hour shorter, thanks to the Earth's gradual slowdown.

In a world filled with so much uncertainty, it can be reassuring to have that one constant.

And this sentiment is shared across much of life on Earth.

Most organisms have evolved to anticipate these daily changes.

Plants, animals, fungi, algae, even cyanobacteria all possess internal clocks that control the timing of biological, physiological, and behavioral responses.

I love that we see it even in bacteria.

Again,

unbelievably fascinating.

It's so cool.

I also love that someone looked for that.

Right?

They're like, we've got to find it here.

It's not just us.

It's not just us.

It's everyone.

Or is it?

Is it?

That I don't know.

Rhetorical question.

But these behavioral responses or these biological responses, things like sleep, like the release of certain hormones or like feeding that occurs at certain times of day or night.

And we call these rhythms that, or these responses that repeat over a roughly 24-hour period, of course, our circadian rhythms.

The ubiquity of these rhythms across all or almost all of life, I guess I don't know what's going on in like the worms that live in the deep sea vents,

whether they have circadian rhythms.

They always mess things up.

I don't know.

They could have.

They probably still do somehow.

Something, yeah.

We'll find out.

Yeah, we'll look into it.

But it just speaks to how important these rhythms are.

But why?

Why would it be so crucial to partition our activity or our physiology across a 24-hour period?

That's my question.

Why does it matter?

In a word, optimization.

Our external environment changes in many ways every day.

Food availability, predator activity, temperature, when other members of your species are also out and about.

You want to spend your energy where it counts.

If you're a bird who relies on color vision for foraging for berries, you probably want to do that during the day when the light actually helps you pick out those colorful berries.

You can see them.

You can can actually see them.

That helps.

But if you're a small prey mammal species like this flying squirrel, maybe running around at night is your best bet to escape predators or flying around.

You also don't want to be active all the time.

That would be exhausting.

Our sleep is incredibly important for housekeeping tasks that our body can't do while we're running around.

And circadian rhythms help us optimize how we spend our energy and when it's safe to get the rest that we need to recuperate.

Anyone who has pulled an all-nighter or who has had to run on a few stolen hours of sleep after welcoming a newborn knows the pain of being out of sync with the world.

But for the most part, we can easily recover from these one-time or short-term disruptions.

But what happens when there is a constant mismatch between your internal clock and the external environment?

Well, we know from what you just told us, Erin, that it's really not great.

Not good for humans, at the least, not good for most, if not all, of the animals we've studied.

And decades of research have shown that it's not great for really anything.

So let's take a minute to get into the story of how we came to understand these rhythms of our lives and the consequences of their disruption.

Humans have recognized circadian rhythms in ourselves and other creatures for millennia.

Aristotle in the 4th century BCE noted that bees slept.

Bees.

Bees slept.

How cute is that?

4th century.

4th century BCE.

BCE.

I love that.

They're just cutting open hives, being like, oh, that one's asleep.

Oh, yeah, I'm sure.

Sorry for disturbing me.

Tucked up like this.

It's very cute.

So cute.

And around the same time, Androsthenes observed the leaves of the tamarind tree curling and uncurling over a day.

The famous ancient Greek and Roman physicians Hippocrates and Galen described fevers that peaked at certain times of day.

What do we think that might be?

I love this.

It's malaria.

It's malaria.

It's probably malaria.

Yeah.

And one of the leading hypotheses for why these cyclic fevers exist is that the parasites match the circadian rhythm of their host or their mosquito vector for more likely transmission.

Like, do they go into the bloodstream at certain times of the day so that that's when the mosquitoes are biting?

It's really.

That's the part that's my favorite.

Not malaria.

It's horrible.

Yeah.

But the fact that they know, and the parasites are like going to be active at certain times to maximize transmission, that's

mind-blowing.

Evolution, man, it's pretty cool.

But for centuries, all of these observations remained just that, observations.

No one attempted to answer the question of why until the 1720s, when a French scientist by the name of Des Meron decided to take a closer look at a plant, specifically Mimosa pudica, which also goes by the adorable common name of sensitive plants.

Or shy plant.

Or shy plant.

And anyone who has interacted with this plant can see where it got its nickname.

When you touch its delicate leaves, they fold in on themselves like, ah, don't touch me.

And then a few minutes later, they'll open back up.

They calm back down.

But it turns out that the plants also do this folding and unfolding routine throughout the day, folding up at night.

Des Maron, observing this, thought to himself, what if?

The two words at the heart of every scientist.

What if they aren't exposed to light?

Then what happens?

And so he plopped the plant into a dark cupboard and saw that it still opened and closed its leaves over that 24-hour period, even in complete darkness.

And so if light wasn't driving this pattern, what was?

In 1832, about 100 years after Des Marin's experiments, Swiss botanist Auguste de Kendall took this question further, placing mimosa plants under continuous light.

Initially, the plants still showed their daily leaf movements.

But as the days went on, de Kendall watched as this pattern grew out of sync with day and night.

Something internal, like an internal clock perhaps,

seemed to be driving these movements, governed by a cycle slightly shorter than a day, around 22 hours compared to 24.

De Candle's experiment was the first to demonstrate the concept of a free-running rhythm, where an organism's internal clock is slightly longer or shorter than a full 24-hour day, and in the absence of external cues, their rhythms will eventually decouple from that 24-hour cycle and instead be guided by their internal ones.

Humans, for instance, 24 and 10 minutes.

24 hours and 9 to 11 minutes.

9 to 11 minutes.

But as it often goes, de Candle's conclusion that organisms are guided by an internal clock, as opposed to responding solely due to external stimuli, was not immediately embraced.

Shock.

Imagine that.

You learn something new and not everyone believes you.

The debate on whether these daily patterns were directed by internal or external forces continued basically up to the middle of the 20th century, coinciding with the peak of the nature versus nurture debate.

But while nature versus nurture seemed to be only increasing in contentiousness, research on rats, plants, birds, bees, even humans demonstrated clear evidence for an internal clock.

Cut off from external cues, mice and rats kept running on their wheel or sleeping right on schedule.

Chickens who had been incubated at at constant conditions still hatched with an innate biological rhythm.

Bees demonstrated a keen sense of time and an ability to communicate that time.

Bees are just an amazing example of circadian rhythms.

And flower timing, they're really good.

You have to like schedule, like have a little schedule calendar for, oh, I need to do this flower then, because that's when it's producing nectar.

Right.

They have it all in a little notebook.

I just imagine getting there a little early and they're like, oh my gosh, late.

Wait, this is, where's the nectar?

Got places to be.

Next one opens in five.

And humans turned out to be no exception to this, as a series of cave, arctic, and underground bunker experiments demonstrated.

The first of these took place in 1938 when physiologist Nathaniel Kleitman called his graduate student Bruce Richardson into his office one day, at least this is how I'm imagining how it went, and said, hey, Bruce, can I interest you in an all-expenses paid, 32-day trip to Mammoth Cave, Kentucky, where we'll hang out in a cavern and try to adjust our bodies to a 28-hour day?

The nearby hotel will take care of our gourmet meals.

You can bring whatever books you'd like.

I've got a deck of cards to play Bridge.

It'll be great.

One deck of cards, 32 days.

Yeah.

Cool.

Well, that's all you need, really.

Yeah, really.

But Bridge, just bridge?

I don't even know how to play Bridge.

Me either.

Two conditions, though.

You've got to record your sleep movements and your temperature at regular intervals.

Richardson said yes.

I mean, who wouldn't?

Like, I would do this.

That sounds fun.

I saw

his advisor, and he's like, well, I can't say no.

That's true.

Yeah.

I tried to do it with ticks.

Do you remember this?

I was sampling in Panama and I tried to measure, see if there was like a diurnal pattern of tick abundance.

And then the rainy season started at

3 a.m.

and I got rained out and I had to leave.

And this is over.

Yeah, it was exhausting.

New experiment.

Yeah, I never did it again, though.

Oh, well, opportunities for the future.

But while the scientific conclusions drawn from this N of 2 experiment, just Kleitman and Richardson, they were a little vague, right?

Richardson apparently readjusted to 28 hours, but Kleitman did not, it made quite an impact on the budding field of chronobiology, drawing the attention of journalists who sketched a story of scientific adventure, as well as researchers who wanted to try it for themselves.

Like Michel Sifré, who spent two months in a cave in the Italian Alps in 1962, waking and sleeping when he felt like it.

Ultimately, when he emerged, he was shocked to find that he had lost two weeks.

He thought, I'll just, it'll be exactly where I think, but no, he lost two weeks.

Because he's too long.

And this work helped to incite interest into the study of circadian rhythms.

And by the early 1960s, the field of chronobiology was born, with one of its leaders, Franz Hallberg, introducing the term circadian rhythm in 1959.

I love that.

It seems so recent.

Recent, I know.

Yeah, it is.

I mean internal clock, I think, was at least from the 1800s.

This is the term circadian rhythm that's more recent.

And since then, researchers examined the process of entrainment, which you described.

And I was thinking about Zeitgebers,

again, apologies for the pronunciation, as kind of like right now how you're giving a talk and you think, oh, I'm right on time.

I'm doing great.

And then someone at the back holds up like a five-minute warning and you're like, whoops, I'm only halfway through my presentation.

I feel like that sign is a Zeitgeber.

Yeah, it's a good analogy.

I like it.

And researchers have examined the mechanistic basis of how these external signals are received by the hypothalamus, eyes, pineal gland, or by some other means.

They've attempted to decipher the genetic basis of biological clocks, identifying clock genes and observing how these genes synchronize across our body to orchestrate broad physiological and behavioral changes during a 24-hour period.

They've done a lot.

Yeah.

A lot.

And this research has been integral to understanding what drives the rhythms of our life, why they're important, and what happens when they're disrupted.

Which brings me to

shift work.

Shift work has been around forever, or at least for thousands of years.

Standing guard, keeping the fire lit, watching over your flock of sheep, caring for the sick or wounded.

The military and certain trades have long required irregular hours, like shipbuilders who had had to work with the tides or rope makers.

I found a quote by a rope maker from 1742.

We cannot make ropes when the sun shines.

We begin at eight o'clock at night and work till eight in the morning, and sometimes we work all day if we can hold it.

I don't know why.

I tried to look into it and I even asked like Blue Sky and I got varied answers and some fun hypotheses, but if anyone knows or has an idea,

please reach out.

Come find me.

But until the late 1800s, shift work was a fairly uncommon occurrence.

Then let there be light.

Specifically, electric light.

In 1892, just three years after the invention of the light bulb, the first power plant in New York opened, supplying continuous power to those who could receive it.

The effect on industry was immediate.

Factories that had to shutter their doors shortly after the sunset or who used lanterns or gaslights for overnight work could now operate around the clock bathed in the glow of artificial light.

For the heads of industry, the benefits of around the clock operation were clear.

Again, the word optimization comes to mind.

Factories could be more efficient while maximizing production, and a 24-hour workday, broken down into shifts, became the new norm for many industries, even those that had not previously required continuous labor.

Shift work was not just something to give them a leg up, but it was becoming necessary to survive the competition.

It was apparent that industry was enjoying an economic boom from this increased productivity, but how were workers faring in this brave, new, well-lit world?

Doing great, I'm sure.

Doing wonderful.

Interest in this question grew in earnest over the first couple decades of the 20th century, and a new concept termed industrial fatigue was introduced to describe the exhaustion caused by overexertion, too long working working hours, and insufficient rest, often measured by a decline in productivity.

All about productivity, Aaron.

Yeah, I mean, so under this framework, human health was reimagined as or equated to the body's capacity for productivity.

So in other words, if you're sick, that means diminished output.

If you're exhausted, that means more mistakes, which means diminished output.

And this concern with worker health and productivity, especially when it came to industrial fatigue, led to the formation of committees such as the Health of Munition Workers Committee in Great Britain, who sought to get a sense of the scope of the problem.

One thing became clear.

People working on night shift were especially prone to industrial fatigue.

So I'm going to read you a quote from a 1918 report by the Health of Munition Workers Committee about night shift.

The objections to night shift may be shortly summarized as follows.

Number one, it is uneconomical owing to the higher cost of wages, lighting, and heating.

Number two, supervision at night is not always so good as by day owing to less effective lighting or to the employment of fewer or less experienced foremen.

Number three, the inferiority of lighting may make work and especially fine work more difficult.

Number four, the workers may be unable to obtain adequate sleep by day.

This may be the result of the dislocation of the ordinary habits of life or of social causes, e.g.

noises and disturbances or the care of children.

Workers are tempted to curtail their period of sleep through rising to join the family midday meal or to obtain some recreation and enjoyment.

Number five, social intercourse, recreation, and amusement may be seriously interfered with.

And number six, finally, it is not natural to turn the night into day and to deprive the body of the beneficial effects of sunlight.

Not natural.

Not natural.

Not natural.

You're not wrong.

So as far back as 1918, people recognized the harm that night shift work could cause.

But the next line in this report reveals the stark reality facing this kind of work.

Under existing conditions, night work at any rate for men and women is inevitable.

And those existing conditions that are referenced in that happened to be World War I.

And then they happened to be World War II.

And then night shift work and shift work in general stopped being discussed as something that was an exception to the rule and slowly became the rule, a normal part of many industries.

From transportation to hospitality, logistics to entertainment, round-the-clock work became a fact of life.

Many countries introduced pieces of legislature that limited the harsh working conditions, especially like long and irregular hours, that had become so widespread during the late 18th and early 1900s.

But shift work remained a staple of industry, growing in prevalence, particularly through the mid-20th century.

I can share a couple of old stats here if you want.

Yes, please.

I love stats.

Okay, so these are from a 1981 symposium.

In France, between 1957 and 1974, the percent of shift work across the workforce more than doubled from 10.3% to 22%.

Wow.

And in some industries, that percentage shot up to 50% and over.

Okay.

In Great Britain, full-time night work was estimated to increase by 1%

every year from the end of World War II to the late 1970s, which 1% doesn't sound like much, but every single year.

Yeah, wow.

The bottom line is that over the course of the 20th century, we've got more people than we ever have doing shift work.

And accompanying this growth in shift work was heightened interest in its health effects on shift workers, as opposed to solely the effects that it had on accidents, injuries, or lost productivity.

Partly driving this change in research interest was the growing field of chronobiology.

While researchers were uncovering the physiological basis of the internal clocks that guide circadian rhythms, they were also exploring what could happen if or when those rhythms were disrupted.

On purpose.

Intentionally.

And as you might expect, this research held great interest to both industry as well as the military.

Can a person ever truly adjust and switch from diurnal to nocturnal?

Spoilers?

Not so much?

Not so much.

And if so, how long does that switch take?

And how easy is it to reverse it?

Right.

Go back to normal.

Can you switch?

Is it every two weeks?

Is it every three weeks?

Is it a month?

Okay.

Can it be done?

Can it be done?

How does shift work alter physiology of different systems in the short term?

And what are some potential implications for the long term?

By the 1980s and the 1990s, some of these long-term health effects of shift work were coming into focus.

Digestion issues, which had long been recognized recognized to be a part of shift work, cardiovascular disease, cancer, immune system issues, diabetes, mood disorders, and a host of social and lifestyle risk factors emerged as possible consequences of shift work, or more generally, a disrupted circadian rhythm and poor sleep.

We have made great strides in our ability to evaluate the links between shift work, circadian rhythm, and health from epidemiological, physiological, genetic, psychological, and sociological perspectives, all the perspectives.

We've also come a long way towards understanding how we can control those risks in the workplace.

But as everyone in this room, everyone listening, can attest, we've still got some ways to go to put what we've learned into practice for sustained improvement and prevention.

We've recognized the negative effects of shift work for over 100 years, since it became a feature of our everyday lives.

And there are some brilliant minds working on innovative solutions to address and reduce the impact of circadian rhythm disruptions at both individual and systemic levels.

And we are so excited to have with us here today one of those brilliant minds, Dr.

Ian Dunikin.

Like Dr.

Eilif, the provider of our first-hand account, Dr.

Ian Dunikin is also originally from Ireland, but moved to Perth where he completed his many degrees, including his PhD in sleep and performance, which he earned at the University of Western Australia.

Dr.

Dunikin is the director and chief advisor of Melius Consulting, a scientific consultancy undertaking research, consulting, and education.

And he also hosts and produces the Sleep for Performance podcast, Fellow Podcaster.

On top of all of that, Dr.

Dunakin is also an adjunct senior research fellow at the University of Western Australia and is involved in numerous research projects related to sport, shift work, nutrition, safety, death, and psychology.

So, please join me in welcoming Dr.

Dunakin.

Thanks so much for coming.

We made this meme just for you.

Yeah.

This is the first time I ever heard my name and brilliant together, so we can retract that afterwards in the end.

Don't worry, we can cut.

Thank you so much.

We're really, really excited to chat with you.

We're going to just pepper you with questions.

Ready?

So like Erin kind of has described already, we've known for a really long time that work that disrupts circadian rhythms can be pretty detrimental to human health.

So if we look first from a systems perspective, what measures can organizations or companies take to help reduce the impact of shift work?

Yeah, it's a good question.

I think it's really important to take a systematic view.

Many companies tend to just chase one thing and go, ooh, let's get technology.

Let's look at rosters.

So we always advocate a system view.

And we have this paper that we published a couple of years ago in Safety and Health at Work, which has 14 elements.

And it's very holistic.

Some of those key elements obviously include things like shifts and rosters, sleep disorders, which many people really don't focus on.

And I know you spoke about sleep happening earlier on.

There's over 770 recognized disorders by the American Academy of Sleep Medicine that we follow here in Australia.

But typically many companies just administer a questionnaire like the

sleeping scale and they think that's an actual sleep disorder program when it's not.

So we need to look more holistically there.

Other components include educating our workforce and that's not just a few slides and an induction.

That's actually spending two to three hours, you know, like what you've done here today, in more detail about how to manage shift work at a personal level around sleep patterns, diet, nutrition, commuting to work, if travel's involved as well.

So, these are just some of the elements that we would take in a system view as well.

But another crucial aspect not to be overlooked is actually staffing.

Because if we don't have enough people to do the job, we're just going to lead to more overtime, more stress on the individuals, and more rework.

And so, it's very important at the first level that we have the staffing correct before we start trying to implement the system.

And finally, on this point, you don't actually have to have a system that stands alone.

That system could be integrated in your health, your safety, your other sort of systems there in a business.

So it doesn't have to be a standalone or a newly constructed system.

It may exist in other ones as well.

Okay, that makes sense.

Yeah.

Yeah.

And so maybe you're lucky enough to work at one of these places that does incorporate a more holistic view of sleep and shift work, or maybe you're not.

But what can anyone do at an individual level to kind of reduce the negative impacts of shift work?

Yeah, I think at the individual level I think you've done a really good job today of highlighting some of the negative impacts.

But what a lot of studies haven't done is looked at what is the benefit of some of the interventions or case control studies where people are doing something going forward.

The first thing I would say to anybody undertaking shift work is keeping your own physical fitness and mental health in check is number one.

So, you know, excessive alcohol consumption that we see, excessive nicotine, caffeine use that we see in shift workers.

We need to bring that back into normal, tolerable levels.

When we start increasing our body weight, that's going to lead to things like sleep-related breathing disorders.

It's going to lead to more of that generalized fatigue that you define at the start as well.

So it's really important that your own physical fitness and mental health and well-being is in check and in shape.

And that's really key, I would say, for individuals.

And also, as well, when you are away undertaking shift work, whether it's here in Western Australia or elsewhere, like in the classic fly-in, fly-out, is having a routine.

And that routine doesn't mean going to the pub every night and having drinks.

That routine may involve some exercise, connecting with other people, family and friends back home as well.

So it needs to be holistic in nature as well for the individual.

Just being healthy, you mean?

Yes.

Which is difficult when you're working 12, 13 hour days.

But you've got to make time.

And I would say to people as well, don't think about going to the gym as a one or two hour exercise.

Even 15 to 20 minutes of high-intensity exercise can be really good for you.

Yeah.

And just having that routine.

Right, which is such a hard part to maintain.

Especially important if you're on those rotating shifts or things like that, but that makes a lot of sense.

Yeah.

So a hot topic, hot button topic these days, why we made you this meme, is our screens, especially our personal devices, and especially the use of those at night.

So I want to ask you, what do we actually know about how much these devices are disrupting our sleep or disrupting our circadian rhythms and contributing to things like fatigue?

And how much of it is the light or the things that we're doing with our devices?

So do you want the scientific answer or do you want the clickbait answer?

I want your answer is what I want.

Because I won't give you the clickba answer.

It's really interesting because we did discuss this a few weeks ago.

However, over the last few days, there has been a bill introduced in Australia to ban social media.

What?

Yeah, so this was passed the other day, I believe.

I'm not getting into politics.

I'm not going.

That's as far as I'll go.

So if we look at electronic device use and its impact on sleep, There's two ways of looking at this.

One is the subjective evidence.

How do people report they feel with electronic devices?

And two is the objective evidence.

What's happening in laboratories with polysemography?

What's happening with actigraphy of risk-worn devices?

The subjective stuff is saying, ooh, this is really impacting my sleep.

The objective stuff is saying it's not.

So the science and the data and the quantitative method actually is showing very little.

of how it's out there.

We're currently undertaking a systematic review and a meta-analysis.

A few scientists are on that from around the world.

Russell Foster, who you may know, who actually discovered the SCN, he's on that paper with us as well.

And so what we're finding so far, self-reported stuff, very influenced, I think, by the media and the general population.

I've ran two studies in athletes, no impact onto sleep.

However, there's three mechanisms how electronic devices may be impacting sleep.

One is the light emitting from these devices.

That could be TV, iPad, social media, could be anything or gaming.

Two, the nature or the stimulating activity.

And many of us in this room do this.

We get home, put the kids to bed, do our exercise, whatever it might be.

And then we go, ooh, a bit of me time.

I put on Netflix, open up my laptop, do some emails.

I'll check Instagram as well while I'm having a glass of wine and healthy dark chocolate.

And it's all this like stimulation plus alcohol plus caffeine.

And then you wonder why you can't sleep.

I wonder why.

Not a single explanation there.

And as you've explained

in your review earlier on, is in the graph, is when cortisol is high, melatonin can't be released.

So furthermore, it's stimulating activity.

We cannot release melatonin or it delays the time of melatonin.

But also, as well, artificial light may have that impact, as we said.

And the final thing is that we're replacing sleep time with other time.

Classy example is: I'll just watch one more, and tonight, Yellowstone is out as well.

But the bad part about Yellowstone at the moment, which is also good, is there's not one more episode because it comes out weekly.

That's the trick.

That's why streaming services are ruined, right?

So that's what we can actually blame is Netflix.

Yeah, no.

No, you can't blame Netflix.

Yeah, it's on stand here in Australia, anyway.

So you can blame Netflix, but not stand.

That's why I'm wearing my Orin Williams boots and belt today for Yellowstone.

I was going to wear a hat, but my wife said, no.

I recently bought an ice of Cubra.

So it's those three mechanisms, the light, the type of activity, and then replacing sleep time.

But so far, we are not seeing a definitive link.

A couple of weeks ago, we had the Australasian Sleep Association conference in the Gold Coast and even a massive study looking at body motion cameras with kids.

No result, no impact on sleep.

Wow.

It's so interesting because all of the recommendations are still like no screen time, one hour, two hours before bed.

Even like all the sleep, you know,

organizations still like recommend that blanket statement, which is so interesting.

But it's not definitive, but what I would say to people is if you're having trouble sleeping, shift work disorder, sleep onset insomnia, trouble winding down, eliminate that activity before bed, lessen that light.

And just basically use that time to basically just wind down and calm down.

Which probably leads in to the recommendations on light.

Yep.

Yeah.

And And this is something that we're really seeing now.

Yeah, that makes a lot of sense.

That makes a lot of sense.

And so this may or may not be a question of personal interest, seeing as we just traveled across nine and ten time zones.

Or a million time zones, is what it feels like sometimes.

But what can we do to minimize or escape the effects of jet lag?

Like,

are there any tips or tricks, or are we all just doomed to be sleep deprived and brain fog and groggy when we cross more than a couple of time zones?

Yeah,

you really are, but you can listen to that.

Yeah, the answer is yes, but

you're going to be impacted by jet lag.

There's no escape now.

There is no biohack, regardless of who you listen to on a podcast, you cannot biohack out a jet lag.

And then people go, what happened years ago when people came to Australia?

They came on a slow moving ship.

It took six weeks.

So they slowly adjusted.

But now we have this rapid trans-meridian travel, which leads to jet lag.

So you can do some pre-adaptation, like with shift work, but a lot of people can't do that because they're trying to work before they go.

And then you've got to really kind of use rapid adaption when you get there.

And going east and west will have different effects, like switching from days to nights or nights to days and shift work.

And so there's many things you can do.

The number one thing I would say is light.

Light is key.

So for you two here today, trying to get over jet lag, this is the worst environment you could be in.

Nice and dark, nice and cool, artificial light, no zeitgeers, no time gearbox.

It's a bit like a casino.

And that's what they do in a casino.

They use all those things against you to keep you in there.

You have no idea

what's going on.

And now at 12 midnight, that we are now,

you've got no idea what time it is.

And so that's what's happening there as well.

But with that, I would say for people trying to overcome jet lag is light and natural light is key.

So today I would recommend as much natural light as possible.

That's the number one mechanism you can do.

So don't get off the plane and go straight to the casino.

Go outside, get some fresh air and get some movement.

Oh, I love it.

We have one last question for you.

It seems like a very exciting time to be working in these fields in coronobiology and sleep science.

What are you most excited about or most hopeful for in the future of this field of research?

I think some of the most interesting research is coming out of Flinders University in Adelaide at the moment and it's looking at light.

Now I'm separating the word light from social media and I'm looking at the impact of light on our health like you spoke about artificial light, people working in nighttime and so on.

Sean Kane, Andrew Phillips, Angus Burns, some of those guys there are doing some really interesting work around the long-term impact of light and they're using the UK biobank data to show the impact on cardiovascular disease, mortality, all of these things as well.

And as you said earlier on,

in this research space, still lots to do, but we know that so far that less than 3% of people can fully adapt to permanent night shifts.

And that's very, very few people, but most people think they can.

So you cannot biohack your way out of this.

There is no free ride.

And you've really displayed that today.

So what I would say is that the sort of the light and the science is really key going forward and the final part is i think using individual sleep uh tracking metrics is really key for the future because we have to individualize this and we're starting to look at individualizing light as well because people have different sensitivities to light some people can be in a brightly lit room go straight to sleep other people can't yeah so looking at more an individual level of sleep and wake patterns and individual light sensitivity as well is the next phase i think we're going to get into oh yeah i can't wait fascinating i know i have a million more questions but i know that we do have to wrap this up.

So thank you so much for sharing your expertise with us today.

That was super fun.

Yeah, we were really excited.

If everyone here also got really stoked about this and wants to learn a lot more about circadian rhythms, about shift work, we have a very long list of the sources that we use to put together this episode.

There's another page.

There's a lot.

Just come and find us.

And I've got a ton of sources for this, but we always shout out just a couple that we want to specifically highlight.

So two in particular.

One is a book by Russell Foster and Leon Kreitzman titled Circadian Rhythms, A Very Short Introduction, published in 2017.

And on the history of shift work side of things, there was a great 1986 paper by Gordon et al.

titled The Prevalence and Health Impact of Shift Work from the American Journal of Public Health.

And then I also had a number of sources, a couple really great overview papers about circadian rhythm that I loved.

One was from The Lancet 2022 by Meyer et al.

titled Circadian Rhythms and Disorders of the Timing of Sleep.

And that that was part of a four-part series that was also really, really great.

And then another one from the New England Journal of Medicine by Aleda and Bass in 2021: Circadian Rhythms in Medicine.

But we had a lot.

We always post them on our website, this podcastwillkillyou.com under the episodes tab.

You'll be able to find this list of all of our sources.

My book, my books.

I was going to say, please,

end your session.

Yeah.

I just released a book today for pre-order on

and it's called, I'm very much, it's a ghostwriter.

And it's called A Guide for Sleep Health and Shift Work.

Love it.

And it's got over 240 references in it.

And it's designed for people doing shift work, organizing sleep and shift work patterns.

It's available for pre-order.

It's up on LinkedIn.

It's on our website, Miles Consulting.

Fantastic.

Please go over there and do it.

And tomorrow, we have a fatigue management symposium from half past one to half past two.

And we'll be delving more into this with

five speakers in that session.

Excellent.

That's going to be great.

Thank you.

Well, and a big thank you again to Dr.

Eilif and also you, Dr.

Dunikin, for sharing sharing experience and expertise with us.

We really appreciate it.

Yeah.

And thank you again to Zach Bentley, Kelly Fipers, David Lowry, and everybody else here at AOA.

Oh, I can't say it.

I know.

And I say the H wrong, I know.

H.

H.

No.

Thank you, everyone,

for inviting us and for organizing this conference.

We're really, really excited to be here.

And we've got a couple more of our usual outro episode thank yous, which is thank you to Blood Mobile for providing the music for this episode and all of our episodes.

Thank you to Liana Scolaci and Tom Breifogel for their amazing audio mixing.

Thank you to everyone at Exactly Right.

And a huge thank you to our amazing listeners, including everyone here today.

Thank you, thank you, thank you.

And until next time, wash your hands.

You filthy animals.

I've never said that to people in real life.

Sorry.

I'm so sorry.

Hi, I'm Morgan Sung, host of Close All Tabs from KQED, where every week we reveal how the online world collides with everyday life.

There was the six-foot cartoon otter who came out from behind a curtain.

It actually really matters that driverless cars are going to mess up in ways that humans wouldn't.

Should I be telling this thing all about my love life?

I think we will see a Twitch stream or a president, maybe within our lifetimes.

You can find Close All Tabs wherever you listen to podcasts.

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