In this episode, we meet Dr Carmel Harrington, Executive Sleep Guru.
Dr Harrington has been working in the world of sleep for nearly 20 years. A former lawyer and educator, she has a PHD in Sleep Medicine from Sydney University and consults with companies and educational institutions both here and overseas on sleep health.
An internationally recognised sleep expert, she is amazed at the seemingly little importance given to sleep. Emerging research clearly shows that sleeping well is a key component to optimal performance and health and if we want to be at the top of our game we need to ensure we get the best sleep possible.
Dr Harrington is the Managing Director of Sleep for Health and an Honorary Research Fellow at the Children's Hospital Westmead. She has written two books “The Sleep Diet” (MacMillan Press 2012) and “The complete guide to a good night's sleep” (MacMillan Press 2014).
In this episode we talk about:
- The crazy myths we carry about sleep and how short-circuiting this vital human function does far more than just make us tired;
- The different kinds of sleep and how many hours we need each night;
- Polyphasic sleep, caffeine, alcohol, and diet; and
- What to do when you can’t sleep.
Connecting with Dr Carmel Harrington
You can reach Carmel via her website, sleepforhealth.com.au.
Books and resources mentioned in the episode
- The Sleep Diet – by Dr Carmel Harrington
- The complete guide to a good night's sleep – by Dr Carmel Harrington
- The 4-Hour Body – by Tim Ferriss
“The big test is, I guess, how do you feel the next day when you wake up? Are you able to meet the joys and challenges of the day? We've got that terrible to-do list. We know we've got to do this, this, this and we knock them all off. But can we meet the joys?”
On why sleep is so misunderstood
- One of the reasons we haven't respected it is that we knew so little about it because everyone thought we just sleep when we're tired.
- We think of it as a passive state, but sleep is not passive; we now know that sleep is a very, very active time, both for our body and for our brain. Our body performs essential functions during sleep that it actually can't perform when we're awake.
- So what we do is repair and restore our cardiovascular system and our nervous system and we secrete lots of this beautiful growth hormone that allows our muscles to build and repair so that we're physically well during our wakeful hours.
- But our brain is doing all sorts of work that it can't do when we're awake because we're busy in the process of being awake. When we go to sleep at night our brain does all the internal stuff that it needs to do so that we can reset information, memories and emotions and all that so that when we're awake we can again respond to the external environment. It's very harmonious.
- What we do in our sleep really affects how we spend our wakeful hours, and in fact, how we spend our wakeful hours affects how we sleep. It's a very harmonious process and it's really unfortunate that people don't relish the idea of a good night's sleep because that allows them the next day to achieve their personal best.
On the different types of sleep
- One of them is our rapid eye movement sleep, this is also known as REM sleep or dream sleep. In dream sleep, our body is paralysed and that's for a very good reason because our dreams are so vivid that we would act out our dreams if our body wasn't paralysed. But our brain in dream sleep is very, very active and in fact, parts of our brain are more active in sleep than they are when we're awake, which is really incredible.
- Some of the things that we do in our dream sleep is we bed down memory and learning and if we don't get enough sleep we actually lose 40% in coding ability. So we lose 40% of our memory because we don't get the chance to encode it into our brain, as you would a computer.
- We also reset our emotional balance so that when we wake up in the morning, not everything is annoying us. We don't get frustrated really easily. So if we don't get enough sleep, of course we recognise that often we're more irritable and cranky and easily angered.
- Then we have non-rapid eye movement sleep or non-REM and there are two different stages in that. There's light sleep and there's deep sleep.
- Most of our sleep as adults is light sleep and that is also very important for memory.
- Then we sink into deep sleep, which is so important for our physical good health as this is where we get the secretion of beautiful hormones that keep us metabolically well when we're awake. Deep sleep is when we are the quietest we will ever be in the 24 hours. Our heart rate goes right down and our breathing rate.
- After about 40 minutes in our first cycle of deep sleep, we'll pop up into our dream sleep. The first cycle of dream sleep is normally very short, it can only be about five minutes and then we'll go back into light sleep.
- The full cycle of going from light sleep, deep sleep into dream sleep is called a sleep cycle and they range from anywhere between 90 to 110 minutes. We get most of our deep sleep in the first third of the night and we get most of our dream sleep in the last third of the night.
On how much sleep is enough
- Everyone wants a silver bullet, don't they? Actually study after study has shown that, as adults, we need somewhere between seven to nine hours. On average we say eight but you might need seven and a half and I might need nine so anywhere between seven to nine is completely normal.
- About 2% of the population have a short sleep gene so they only need somewhere between five to six hours to get done everything that we need seven to nine.
- And 2% of the population have a long sleep gene so they need slightly more than nine hours to perform those vital tasks that I was talking about.
- The big test is are you able to meet the joys and challenges of the day? Life should be joyful and one of the things we first start to miss when we're sleep-deprived is the joy of success, the joy of our children and it's just more on the to-do list.
On the crazy myths we carry about sleep
- We know somewhere between almost one in two of us adults are getting less than seven hours of sleep. So half of the Australian population is sleep deprived.
- A lot of adults try to catch up on the weekend, so they sleep longer. You can actually make yourself feel a bit better because you're refreshed but you miss out on all those things that you did night after night, like repairing your cardiovascular system or your nervous system, or your respiratory system, or you haven't produced all the beautiful growth hormones that you needed to have good metabolic health all during the week. Likewise with our brains. You can't catch up on those things on the weekend in a couple of hours' sleep.
- When we sleep our brain cells retract by about 50% and that allows our spinal fluid to wash over our brain and it cleanses our brain which is like having a shower at the end of the day, which is great.
- Importantly, sleep gets rid of this metabolite called beta-amyloid peptide. This peptide is a very sticky protein and it forms clumps or plaques in the brain and these plaques are implicated in the Alzheimer dementia process. These plaques form up to 20 years prior to the overt presentation of dementia, so if we're not getting enough sleep on a regular basis, we really do suffer the consequences later on and we can't actually undo that.
On sleep deprivation in the real world
- In one research study, they took two groups of people and one group of people they actually deprived of sleep for two nights, so they maintained wakefulness for 48 hours.
- Then they took another group of people and took away two hours' sleep per night for 10 nights. So they were only allowed to sleep up to five hours. That sort of mimics real life, doesn't it?
- Well, the sad fact is that they actually performed (in a speed and accuracy test) as badly as the people that were totally sleep-deprived.
- We lose our ability to reflect about our sleep deprivation. We actually don't discern it subjectively ie. we think we're going okay when in fact we're not. But objectively our performance is equal to two nights of total sleep deprivation!
On power naps and polyphasic sleep
- Yes, power naps are great and as most of us realise, we have the lull in our alertness about 3 to 5 o'clock in the afternoon, depending on whether you're an early person or late person. This is a really good time to have a power nap and a power nap should be only about 20 minutes and you set an alarm, so 20 to 25 minutes. And a power nap does not interrupt or affect your ability to sleep that night, whereas a longer sleep may well do.
- Polyphasic sleep is lunacy for most of us and often people will suffer quite severe consequences mentally, with their mental health. There's nothing wrong with polyphasic sleep, provided you're still getting your seven to nine hours. But most people doing it only get eight lots of 20 minutes, which is not very much, so they're really, really sleep deprived.
- The other thing that can start to happen is they start to sleep and they don't know they're sleeping as well. So they have microsleeps when they can least afford to have them. They may not even be aware this is happening as well.
- If you can't get two sleep cycles in a row, like a mother of a newborn, try to add up what you're getting and make sure it's in the vicinity of seven hours per 24 hours.”
- A lot of shift workers, though are biphasic sleepers so they might have a four hour stint when they get home from their shift and then three hours just before they go to work that night, so they can be biphasic sleepers.
On preparing your body and mind for sleep
- If you haven't spent enough time preparing your mind for sleep and you're in a busy world, it's like getting out of the car with the motor running. So one of the key things is to disconnect from the world one hour before your planned bedtime.
- We actually need to put some discipline around our mobile devices. We live in quite an undisciplined time in regard to our technology, it tends to control us, we don't control it. It's time to say, “Okay, look I love it for 15 hours a day, but for the other nine hours, I don't love it. I'm not going to use it. I'm going to switch off one hour before bedtime.
- So you can have a warm to hot shower, you dim the lights in the bedroom because we need that dim light to produce our beautiful melatonin. Maybe do a relaxation exercise, maybe talk to your partner.
On what to do when you can’t sleep
- What you need to do is at the end of your working day, write down in a diary, a worry diary or whatever you want to call it, things that popped up during the day that you haven't had an opportunity to address. Write them down and write down potential solutions or what you're going to do about it. It's not War and Peace, so 10 or 15 minutes. At 3 o'clock in the morning when you wake up thinking, “Oh my gosh, I haven't done this or that” you are able to think, “Okay it's in my book. I don't need to worry about it.”
- If you start to get anxious, you should turn your attention to bringing down our breath rate. So we breathe in for one, and out for two. Do that over and over again and you'll notice that you actually reduce your heart rate and so does our blood pressure. And we stop producing the adrenaline and the cortisol that's going to keep us wide awake.
- Once you’re relaxed, you can do progressive muscle relaxation. What you do is you move up your body – start with your feet, you tense your feet for five or 10 seconds and then you relax. Then you tense your calf muscles for five or 10 seconds and then relax. And then your thighs, and you just move up your body all the way to the tip of your head. Just gradually tensing and relaxing and feeling that tension go out of your body through the bed and through the floor.
- By the time you get to the top of your head often we're sound asleep already but if you're not, don't worry, just accept it and if you can't sleep and you're still stressed, you get up.
On caffeine, alcohol and diet
- Caffeine does affect our ability to get to sleep and stay asleep. When we're younger we can probably have coffee within about four to five hours of bedtime, but as we age, so too does our metabolic rate slow. That means that as we age we process caffeine much slower. So from about the age of 40 onwards, you really should be avoiding coffee from about just after lunch, because we can take up to eight hours to work through the caffeine.
- Alcohol is a sleep stealer and often people are surprised by this because they say, “Oh no, a couple of glasses of wine really help me get to sleep.” Well actually they do relax you, and in fact, if you have enough of it, it comatoses you. But it is a toxin and so our body goes into overdrive to metabolise and get it out of our system. What happens about four or five hours after your drinking and going to sleep, you'll wake up, you'll be dehydrated, you'll be hot and your heart will be going faster and indeed you'll find it very difficult to get back to sleep again.
- The big thing to look out for is not to have a large meal within three hours of bedtime. Especially spicy food. You may well get to sleep and then find that your sleep is quite fragmented or that you only stay in light sleep, you don't get any of that lovely rejuvenating deep sleep because the body's busy digesting the food.
Final message of wisdom and hope for future leaders
- I think we have to just remember that life is long. Don't try to live it in a day. Take time and there's a lot of joy involved, it's not just that quick rush to the deadline all the time. I just think life is long and we can shoot for so much more when we've got longevity up our sleeve.