After her son died of SIDS, Dr Carmel Harrington left her job as a lawyer to devote her career to finding answers.
“You blame yourself. You must have missed something. How can such a catastrophic event occur without any sign or symptom?”
Her groundbreaking research into SIDS opened up another mission: to wake society up to the critical importance of sleep.
Carmel is the managing director of Sleep for Health. High-flying CEOs and even the Australian military are now turning to her expertise in a bid to master the art of sleep.
The stakes are high. In our wired world shut-eye often proves elusive – and that can have deadly consequences.
Sleep loss is linked to heart disease, cancer, dementia and depression, and it also affects your ability to think and learn.
Carmel explains how to sleep better, the incredible things that happen when you sleep (Brain washing! Memory encoding!), and what to do about technology in the bedroom.
She’ll also teach you how to spot subtle signs of sleep deprivation.
“One of the big things I like to talk about is, have you lost joy? So often with A-type personalities, we are very good at meeting the challenges of the day - but how good are you at enjoying the joy in your life?”
Carmel’s latest book is The Complete Guide to a Good Night's Sleep.
Mark Scott 00:01
This podcast is recorded at the University of Sydney's Camperdown campus on the land of the Gadigal people of the Eora nation. They've been discovering and sharing knowledge here for tens of thousands of years. I pay my respects to Elders past and present and extend that respect to all Aboriginal and Torres Strait Islander people.
Dr. Carmel Harrington 00:27
When you go to sleep, something really amazing happens. You get brainwashed, literally. First, your neurons go quiet. Your brain cells, which are usually really tightly packed like sardines, shrink a little bit, so there's spaces between them. A few seconds later, blood flows out of your brain, then a watery liquid called cerebrospinal fluid flows in. It washes through your brain in rhythmic pulsing waves, clearing away waste products that are toxic to your brain cells. It's like giving your brain a shower every night. This keeps your brain healthy and might even ward off dementia and Alzheimer's disease. Wash, rinse, repeat, all while you sleep.
Mark Scott 01:24
Let me start by invoking those great Australian poets – the Hoodoo Gurus. “I'm so tired of waking up tired. The lights are on but there's no one home because I'm so wired from waking up tired. I need a month of Sundays to help me cope with Mondays. I just want to stay right here, safe and sound.” You know that saying ‘you can sleep when you're dead’? Well, that advice could actually kill you. A lack of sleep hurts your body and your brain. It's linked to cancer, heart disease and dementia. And it costs the economy billions in lost productivity. But in our busy world, sleep can feel like a luxury. And many experts fear we're sleepwalking through a public health epidemic. I'm Mark Scott, the Vice-Chancellor of the University of Sydney and this is The Solutionists. Dr. Carmel Harrington is the managing director of Sleep for Health in Sydney. She's worked with parents, high flying CEOs, and even the military to help people get better sleep. Hi Carmel.
Dr. Carmel Harrington 02:42
Hi Mark.
Mark Scott 02:44
Carmel, do we need a wakeup call on sleep? Just how important is it?
Dr. Carmel Harrington 02:50
Well, it's fundamental. You know, we often think about the pillars of health being nutrition and exercise. But we have a third pillar of health that is really totally overlooked, which is sleep. And without good sleep, we all struggle to get good exercise and good nutrition. So, sleep really underpins how well we behave, think, feel, and every aspect of our life. So we know that the effects of chronic lack of sleep are quite significant, and we have a 50% increased risk for obesity or metabolic dysfunction, twice the risk of a cardiovascular disease, a 30% increased risk in some hormonal cancers, [and] an increased risk in vulnerability to cold and flus. We have a two-to-three-fold increased risk in development of dementia, or cognitive decline as we age. And the other factor that we need to recognise in our society today is the increased risk of depression, and that's very much associated with lack of sleep. In fact, there's a fivefold increased risk of developing depression if you have sleep issues and are being sleep deprived.
Mark Scott 04:00
So how tired are we? How many people are walking around in Australia, or around the world, who are sleep deprived?
Dr. Carmel Harrington 04:08
Well unfortunately, it's [a] really high figure, and there was a recent study Deloitte undertook looking at the economic burden of sleeplessness in Australia, and I think they found about 48% of people were getting less than seven to nine hours recommended in their working week. Certainly, I think it's time for an education campaign telling people that this, I mean, there's an economic burden, but there's a huge health burden, and there's a personal burden. So now is a good time for people to wake up to the importance of sleep.
Mark Scott 04:36
How does sleep affect our ability to think and learn?
Dr. Carmel Harrington 04:40
Oh, it's enormous. So one of the things or many things our brain does when we sleep is bed down memories. So memory is a very complicated process and the hippocampus is very much involved in it. And if we don't sleep enough, what we find is that we lose the ability to encode memory. So, if we are sleepless and have no sleep at all, we actually lose 60% of our encoding ability. So it means that you might spend all that time learning or doing whatever, but you actually don't encode the memory. So it gets into the hippocampus, but it doesn't get out. And it's in that process of getting out and being circulated throughout the brain that we actually encode the memory for our thinking process.
Mark Scott 05:24
And so that would mean for students who are listening, the idea of an all-nighter, where they're studying all night, is kind of counterproductive to actually being able to remember what they've been learning and use it in the exams the next week.
Dr. Carmel Harrington 05:38
Absolutely. And the kicker in all of that, that's so true, they actually don't incur what they expose themselves to. But your prefrontal cortex, that front part of the brain that is most developed in humans and is responsible for our brain smarts, actually starts to shut down. And studies have shown that when it's not well slept, it finds it very difficult to recruit parts of the prefrontal cortex so that your thinking processes or your cognitive processes are not very good either. So the worst thing you can do is not get good sleep prior to an exam, or an important meeting, or the thing that requires your brain to be the active and effective brain that you've been hired for.
Mark Scott 06:20
How do we know if we're chronically overtired? I often reflect on this, what does great sleep feel like?
Dr. Carmel Harrington 06:27
Great sleep means that you wake up, you have no inclination to go back to sleep, you haven't had to use an alarm clock to wake up. You don't need coffee or energy drinks constantly throughout the day. You don't fall asleep as soon as you are in a passive situation, like you sit on the couch and you fall asleep, or you're sitting, even talking to someone, and people might even nod off. So they are the big indicators of that you are not getting the sleep that you need. The other thing, one more, is that what we call going to sleep or our sleep latency. If you've got a really short sleep latency, like as soon as you put your head on the pillow, you're asleep, you can't remember going to sleep, that indicates that you're carrying a sleep debt.
Mark Scott 07:10
And how long does it take to overcome a sleep debt?
Dr. Carmel Harrington 07:13
Yeah, look, there's a lot of work around this, it's looked at. And by and large, it's thought that if you are, say, in a deficit of 20 hours sleep, for example, you need to pay back 10. So two for one. But, you haven't undone all the damage that you did in that period of time that you were not sleeping, alright. So you got to recognise that on a day-to-day basis there is a cost that you just don't actually make up just because you've decided three weeks later that ‘I'm going to pay back that 10 hours’.
Mark Scott 07:45
We hear all these stories about high profile leaders, you know, Winston Churchill, Margaret Thatcher, Kevin Rudd, and the boast is they only need four hours sleep. Is that possible?
Dr. Carmel Harrington 07:56
We know that we need, as healthy adults, seven to nine hours. It is an individual need. There are extensions of that. So we have something called the short sleep chain, and the long sleep chain. And it's a rare genetic characteristic. Some people can get by on four to five hours when others need that seven to nine. However, I have met a lot of wannabe short sleepers. And when you drill down, they actually have all the characteristics of sleep deprivation. But they've adapted to having four to five hours sleep.
Mark Scott 08:31
What are the characteristics of sleep deprivation? What does that look like?
Dr. Carmel Harrington 08:34
Well, you're certainly not as engaged in the world as you would like to be. Often we see we're lacking motivation. And we're sort of not as well behaved. So we're a bit grumpy with the children, not as patient with our work colleagues. So there's quite a lot of subtle symptoms, or sometimes they're not so subtle, that we are sleep deprived. But one of the big things I like to talk about is ‘have you lost joy?’ Because so often with A type personalities, we are very good at meeting the challenges of the day. But how good are you at enjoying the joy in your life? So if it gets to the end of the week and you go home and your partner says ‘look, I planned this wonderful big picnic’, or ‘we're going to go out and look at the sunset with a glass of champagne’. And you look at them and think ‘all I want to do is go to sleep’, then perhaps you’re needing more sleep.
Mark Scott 09:25
Jerry Seinfeld had this routine where he talked about night Jerry talking to morning Jerry, and how night Jerry would always think there are many hours ahead to stay up and party and enjoy. But morning Jerry would always resent the decisions that were made the night before. How do we convince ourselves that it's just time to go to bed?
Dr. Carmel Harrington 09:45
Look, the one I recommend is, because we always got that party brain, we just want to keep enjoying, have an alarm clock go off one hour before the proposed bedtime. That then makes you make a decision. Am I going to party on or am I going to take my sleep seriously, because think about your morning brain. And at that point, switch off technology, start to do relaxation exercises, have a hot shower, there's all those sorts of tips for what to do in the hour before bedtime, because by having the alarm clock, it means ‘okay, now I have to make a decision and a proper decision’.
Dr. Carmel Harrington 10:25
In the military, sleep deprivation is often accepted as a normal part of life on duty. Some soldiers believe that they can control how much sleep they need. And others think that they're weak for needing sleep. But soldiers, like everyone else, need sleep, they need it to recover from physically demanding missions. And they need it to help them make split second decisions. That could be the difference between their life or death, or one of the members of their team. So the military is now recognising that we need a well-slept brain to have the high performance that we require. Technology now is pretty advanced in the military, like it actually takes care of a lot of things. But the brain, they recognise, and sleep researchers have known for a long time, it's sort of like the last frontier, this is the thing that's gonna let you down when you're not able to make that split second decision, where you're not able to process new information coming in, or when your prefrontal cortex is shutting down because of lack of sleep.
Mark Scott 11:39
So sleep might be a secret weapon, and not just in the military but at work too. Carmel, you also work with business executives. There's been a recent push to embrace naps at the office. Google has installed sleep pods, I still think they're a pretty unfashionable thing to do. Do we need to rethink that? And what do we know about the power of a nap?
Dr. Carmel Harrington 12:05
Yes, it's interesting the idea of a nap. But now, [with] a lot of people working from home, you might be surprised how many people are actually getting a nap in that afternoon lull. Essentially what you're doing is a neurotransmitter, sleeping neurotransmitter, called adenosine. Now the longer we're awake for, the more [of] this adenosine we build up in our brain. Now, this then tells the brain how tired it is and it increases our drive to sleep. When we have a power nap, A) we don't produce any more of this adenosine, but we actively degrade it, so that when the brain wakes up, it doesn't feel, it hasn't got as high a sleep drive. So we're more alert and our brain function is restored. And it's been shown to be very good in enabling you to have the next four or five hours with an alert, processing brain.
Mark Scott 12:53
Adenosine. Does caffeine interact with that, is that how caffeine works?
Dr. Carmel Harrington 12:57
Absolutely, you’re spot on there. What happens is caffeine hides the adenosine receptors, so the brain doesn't realise how much adenosine it has. And so it doesn't feel as tired, but this is why you get the kick. However, the tow with caffeine is it has a half-life. So you're constantly relying on caffeine, it will come away from the receptors. And in that time, you've built up more adenosine, right. And so if you're about to drive home, you're at risk of a micro-sleep or an occupational accident or whatever it is. So be aware of how much you're using caffeine to hide this adenosine.
Mark Scott 13:34
How important is deep sleep, and the extent to which hours in bed, hours in sleep, hours asleep, you know, seven to nine hours you talked about is one thing, but do we need to be in pursuit of a certain quality of sleep? And how do we do that?
Dr. Carmel Harrington 13:48
Deep sleep is really important for our physical good health, as it is that when you watch somebody sleeping, which I've done over the years many times, I can always see when they go into deep sleep because that is the most quiescent that we are in the 24 hour period. Our heart rate goes down, our respiratory rate goes down, our nervous system activity goes right down. Because our body at that point is busy repairing and restoring its secreting beautiful hormones that make our metabolism quite balanced the next day, it's repairing our muscles secreting growth hormone. So this state of sleep is very important for our physical good health. Now, dream sleep or our rapid eye movement sleep is really important for our cognitive good health and how we think and behave the next day.
Mark Scott 14:36
You and I probably work regular hours. You know, we work during the day, we sleep at night. There are plenty of people who don't have that privilege and that option. Can you be a great sleeper if you're a shift worker and what do we know about the impact of shift work on the physical consequences of the requirements of sleep?
Dr. Carmel Harrington 14:52
Yeah, so shift workers constitute about 20% of our working population and for sure, getting good sleep is more problematic for them. We need to educate our shift workers because guess what, shift work is not going to go away anytime soon. So we need to A) let them know that sleep is a priority. We need to educate them about the importance of the use of light, what and when to eat, when to nap, when to start doing biphasic sleeping or multiphasic sleeping, we've got all sorts of tools in the toolbox to help them get better sleep. But unless they've been educated about this, they just don't know. And this is some of the things I work with [in] high performance teams.
Mark Scott 15:36
Carmel, you were a biochemist and then a lawyer. Then tragedy hit the family in 1991. Tell us about that and what changed everything for you.
Dr. Carmel Harrington 15:46
Yeah, look, life is long, as we both know. And you never know where you're going to end up. So, you're right, I was a biochemist then a lawyer, and I was happily a lawyer, and [that took an] abrupt turn when my son died suddenly and unexpectedly one night. In those days, it was called cot death. Now it's referred to as sudden unexpected death in infancy. Like most parents, you really blame yourself. You must have missed something. Because how can such a catastrophic event occur without any sign or symptom? So, you know, I really was on an incredible guilt trip. But some time after his death, I thought to myself, it's so cruel that that was the night I didn't get up to him because his twin sister Charlotte had very problematic sleeping and I was up every single night dealing with her. And because they're in side-by-side cots, I would fuss around him as well. And so I thought, wow, why was it that that night was the only night I didn't get a chance to check on him. Eventually, when you can start to breathe again, I had thought that maybe he actually couldn't arouse on his own. Maybe it was because Charlotte was arousing him, and I was going in there, that kept him alive for as long as he did. So once I had that thought, that was it. That was the start of my research into sleep and my research into autonomic function. So gave up a legal career, left my marriage, and started a PhD here with Professor Colin Sullivan looking at the autonomic nervous system in infants at risk of SIDS.
Mark Scott 17:23
And what did you find?
Dr. Carmel Harrington 17:25
What I found in that research was that yes, some children who we viewed as vulnerable to this event actually had a deficit in arousal. And so that then started years of other research. And just finally, last year, I published a paper indicating, or showing, that there was an enzyme involved in arousal that was deficient in SIDS infants, infants who had actually died from SIDS, compared to surviving infants and infants who had died from other causes. Now, while I would have loved that to be a cause, it was not, it was a biomarker. Nonetheless, really important, because it now gives us a very clear direction of where we want to go. When I started this research, and I told Professor Sullivan that what I actually eventually wanted to do was develop a screening test, he said, ‘trying to find the cause of SIDS is like trying to find a needle in a haystack’. Now, I think we found maybe one of the needles, but we've got a lot more work to do. But you know, since the time that we've published this paper, I've had the most amazing emails, from mostly mums, who have written to me and said, you know, this is the first time ever that I have not felt I did something wrong, that actually, something's going on in these babies that we don't understand. We don't know how it's going. But for the first time ever, I don't feel responsible.
Mark Scott 18:48
Our daughter recently moved back in home, as people do, with her partner and her new baby. It's wonderful. And seeing all these things, I think the advice seems to have changed a lot since she was a baby. And I think there's a lot of focus and concentration on sleep and safe sleep. What should new parents learn about sleep?
Dr. Carmel Harrington 19:09
So, most people recognise the importance of placing their child in a safe sleeping environment, which includes placing the baby on their back, a smoke-free environment, no toys or blankets around them. If you wish to co-sleep, the recommendation is that you have a little crib within the bed itself, a potty. And so you put the child in that. So co-sleeping is really important, its formed part of our communities for forever. And so we can put the child safely into that potty and then we can breastfeed and just put the child back. But one of the other bits of information parents like to hear is ‘how do I get sleep?’ Because that becomes very problematic. The advice for parents is, do not take turns in getting up to your baby. If you say that ‘I got up half an hour ago, it's your turn to get up’, all that means is that both parents are sleep deprived and both have fragmented sleep. So you have nights on, and you have nights off, and you make that decision before you go to bed. Life's not perfect, but you need to watch also how much sleep you've been getting. So if you've had two nights of really poor sleep, on the third night, you need to reset. So you're not going down that spiral, because we know that sleep deprivation is very much implicated in postpartum depression and we don't want that to happen. So every third night, get the sleep that you need. And I'm talking about both parents, not one or the other. Yeah.
Mark Scott 20:40
Carmel, many people, most people, sleep with the phone on the bedside table. What's your advice about technology, the bedroom, and the phone at night.
Dr. Carmel Harrington 20:51
So my recommendation is we do not have technology in the bedroom. This became particularly problematic through COVID, when people had to, were working from home, and some had to make their bedroom their office. And then we saw all this increase in sleep problems, inability to initiate sleep, inability to maintain sleep. So your brain is very quick to associate different things in your bedroom with sleeplessness. So all technology out of the bedroom. Now people say to me, ‘I need my phone by my bed for an alarm’. That's the biggest excuse I've heard. If you have discipline around your phone, are not tempted to get hold of it at three o'clock in the morning, then that's okay. But if you're finding that you are using your phone, in the bedroom, in bed, then get it out of the bedroom and get an old fashioned alarm clock, because if that's the only reason you've got it in your bedroom, then it's, and using it for other purposes is not good enough, not a good excuse. And sometimes making that simple change can make all the difference in the world. But I don't want people listening to this to feel despair because they have made these changes and nothing's happened. Because over time, what can happen is we build up a resistance to sleep in so far as we start to associate our bed with sleeplessness, not sleep, because of whatever's happened. And so this is very powerful in the brain. And so no matter how much you change your sleep behaviours, you actually can't manage to get to sleep properly. This is actually called psychos physiological insomnia. But luckily, we have a tool at our disposal. Now that works quite well, which is cognitive behavioural therapy for insomnia, or CBTI. It's not a simple fix, but it will fix. It takes a little bit of time, but it doesn't fix things overnight. And lastly, I would just caution about, whether or not you might have sleep pathology, so you might have tried everything. Again, [if] it's not working, maybe talk to your healthcare provider.
Mark Scott 22:49
I'm Mark Scott, Vice-Chancellor of the University of Sydney and a huge thanks to Dr. Carmel Harrington, the director of Sleep for Health in Sydney. Carmel, I know a lot of exhausted people are going to be thanking you as well.
Dr. Carmel Harrington 23:01
Thank you Mark, it's been a pleasure.
Mark Scott 23:07
Make sure you're following The Solutionists in your favourite podcast app, so you never miss a chance to meet the brightest minds working to solve the most complex issues, the people who are making change happen. The Solutionists is a podcast from the University of Sydney produced by Deadset Studios. It's been incredible to meet so many Solutionists this season. We tackled extreme heat, unlocked a love of lifelong learning, and explored the art of bringing people together. We've learned how to age better, and stay younger for longer, and how to give babies the best possible start in life. We'll be back in the new year, exploring the biggest challenges we're facing, in our bodies, in our minds, and in our communities. In the meantime, if you missed anything in season one, scroll back in your podcast feed wherever you're listening right now, and meet the people who are making change happen. I'm Mark Scott, and thank you for joining me on The Solutionists. I met someone last night who said ‘I listen to it going to sleep, I find your voice very soothing and reassuring’, I thought, that sort of links into this. So we help you go to sleep, play my voice and go to sleep.
The Solutionists is a podcast from the University of Sydney, produced by Deadset Studios.
Keep up to date with The Solutionists by following @sydney_uni on Twitter, Instagram, and Facebook.
This episode was produced by Monique Ross. Sound design by Jeremy Wilmot. The executive producer is Rachel Fountain. Executive editors are Jen Peterson-Ward, Kellie Riordan and Mark Scott.
This podcast was recorded on the land of the Gadigal people of the Eora nation. For thousands of years, across innumerable generations, knowledge has been taught, shared and exchanged here. We pay respect to Elders past and present and extend that respect to all Aboriginal and Torres Strait Islander people.