“Roll-up roll-up! Ladies and gentlemen, I am going to tell you about this miracle we are offering here at St. Emlyns that can improve your learning, make you live longer, reduce your risk of developing diabetes, cancer, cardiovacular disease, stroke, mental health issues and dementia, can help you lose weight and even make you better looking. And how much are we charging you for this miracle? We’re not asking $40; we’re not asking $20; we’re not even asking $5; in fact it’s free, and not only is it free ladies and gentleman but you don’t even need to do anything to get it…”
What is this miracle?
Enough of the snake oil salesman talk… It’s simply sleep; specifically 7-9 hours sleep a night. I have recently read Why We Sleep: The New Science of Sleep and Dreams by Matthew Walker, Professor of Neuroscience and Psychology and Director of Sleep and Neuroimaging at Berkeley California, and it’s been a bit of an eye-opener [ironic] to realise how important sleep is to us when it comes to learning. What follows is a brief, simplified, summary of his book and what it means to learning.
All of us have a circadian rhythm; our bodies’ 24 hour cycle that tells us when we should be asleep and when we should be awake through a mixture of adenosine, melatonin and sunlight. For 40% of people, that cycle is that of a lark; asleep by 10pm and awake by 6am to get a full 8 hours sleep at night. A further 30% of us are owls, who ideally would drop off about 2am and wake at 10am for their 8 hours of shuteye.
The astute amongst you will have noticed that 40% larks plus 30% owls don’t add up to a total population… The remaining 30% are somewhere in between larks and owls.
Simon (@EMManchester) is a lark. In fact Simon is the larkiest of all larks – the über-lark if you will! He is up at 06:00 everyday and often awake at dawn if that comes earlier [Just for the record he told me this – I’ve not been stalking his early morning habits!]. Me on the other hand – not so much. Whilst I am not exactly nocturnal, if left to my own devices I would go to sleep about 02:00 and get up at 10:00 but life won’t let me – I am the proverbial owl (it’s 21:50 as I am typing this).
If we look at our relative circadian rhythms Simon (the solid green line) is up at 06:00 and by 09:00 is getting in to his stride for the day. He is peaking in the early afternoon, and by 17:00 he is winding down for the evening, ready for bed about 22:00. Compare that to me (the dotted line). A 06:00 start for me is the equivalent of Simon getting up at 02:00! It isn’t until 10:00 that my body clock levels are the same as Simons getting up levels and as Simon is starting his wind-down for the day, I am just peaking… at home time. Due to being up at 06:00 I will collapse in to bed around midnight, because try as I might I won’t be able to get to sleep before then until much later in the week when exhaustion forces me to.
[Warning: the following paragraph is full of self-pity]
Owls tend to be treated unfairly by the world, being seen as lazy, but the evidence is that we can’t help ourselves; it’s our biological clock that can’t be changed. The rest of the world does us a disservice and makes us less productive by insisting we rise early when our body is crying out for more sleep. To be fair I work in a very forward thinking department [@MFT_UGME] that allows me flexibility in my working, but think how much more productive a department could be, and how much better the coverage would be if both larks and owls were allowed to work to their own body clocks.
8 hours of sleep
the World Health Organization (WHO) has now declared a sleep loss epidemic throughout industrialized nations.Walker, Matthew. Why We Sleep (p. 4). Penguin Books Ltd. Kindle Edition.
You will notice that I said 8 hours sleep… hands up if you get 8 hours sleep a night. I thought not. 7-8 hours – maybe a few of you. Most of us, I suspect, will be getting 6-7 and a few less than 6. Chronic sleep restriction is defined as less than 7 hours sleep on a regular basis. In fact, so many people get less than 7 hours sleep, that WHO have declared chronic sleep deprivation an epidemic in industrialised nations because of the way it affects health described above. And don’t think we can sleep less all week and then make it up at the weekend either – the benefits of sleep isn’t credit that we can pay back later; once we’ve lost it, it’s gone.
Sadly, human beings are in fact the only species that will deliberately deprive themselves of sleep without legitimate gain.Walker, Matthew. Why We Sleep (p. 4). Penguin Books Ltd. Kindle Edition.
Now I can hear your thoughts on this… ‘I don’t need more than 6-7 hours sleep’… ‘I get by fine on less’… ‘I’m more productive’. Yes we get by on less, in fact many do (hence the WHO declaration) but no, we are not fine on it and the evidence is we are not more productive. There are a few people who, due to a certain gene, require less than 5 hours sleep a night but the percentage of the population who have it, rounded up to the nearest whole number, is 0. We are more likely to be struck by lightning than have this gene. In short it’s really, really, really not likely to be you!
How learning happens as we sleep
Studies have repeatedly shown that learning, followed by 8 hours of sleep and then testing, improves performance by 20-40% when measured against 8 hours of being awake between learning and testing, when all other factors are taken into consideration. So how does this happen…?
By sticking people’s heads in functional MRI scanners and from measuring brain wave activity of people sleeping, along with cleverly devised memory tests, scientists studying this now have a good idea of what happens.
Two processes seem to happen during the stages of NREM sleep. Firstly our brain decides what is not important and needs to be forgotten (things like what we had for lunch or where we parked the car) by beginning to breakdown the neural connections it made during the day.
The other thing that happens is that we transfer fact based knowledge from short-term storage (where it’s easily lost) to the safer long-term memory for storage.
In other words, your brain will continue to improve skill memories in the absence of any further practice.Walker, Matthew. Why We Sleep (p. 125). Penguin Books Ltd. Kindle Edition.
Finally during NREM sleep (specifically it seems late stage 2 NREM in the last 2 hours of an 8 hour sleep), our brain mentally rehearses new psychomotor skills, improving what is (incorrectly) referred to as muscle memory. That our brain will continue to improve skills memory without further physical practice is frankly amazing.
the sleeping brain fuses together disparate sets of knowledge that foster impressive problem-solving abilities.Walker, Matthew. Why We Sleep (p. 132). Penguin Books Ltd. Kindle Edition.
During REM sleep we replay what we have learned and look for connections with pre-existing knowledge to create new ideas. So on a simplistic basis whilst NREM sleep consolidates the fact ‘A>B’, REM sleep takes this fact, adds it to some pre-existing learned knowledge that ‘B>C’, and makes new knowledge ‘therefore A>C’ from this.
Hopefully you can now see just how important sleep is to learning. We literally learn as we sleep.
So how does loss of sleep affect our learning?
This is a typical sleep pattern of us sleeping for 8 hours as we flip between NREM and REM sleep. Whilst we flip between the two every 90 minutes or so, the majority of NREM sleep is done at the beginning of the night and the majority of REM sleep is done at the end. This means that if we cut our 8 hour sleep by 2 hours, although we are losing 25% of our total sleep time, we are losing almost 50% of our REM sleep where the brain is doing the higher level learning of making connections between new and old knowledge. Since a lot of our NREM2 sleep occurs in those last 2 hours we are also losing a lot of the mental rehearsal of psychomotor skills.
We are not learning enough because we are tired; so we work late in to the night… We sleep badly due to the anxiety this creates and the amount of coffee we’ve been drinking to try to keep ourselves awake so we can work late… We cut our sleep short and get up early because we have so much to do (or have to be in early) and find we’re not learning enough… We are creating our own negative feedback loop.
What does it mean for learning then?
For every day you are in a different time zone, your suprachiasmatic nucleus can only readjust by about one hour.Walker, Matthew. Why We Sleep (p. 25). Penguin Books Ltd. Kindle Edition.
As I am writing this many people are preparing to pack up and head to probably the world’s best medical conference in Sydney. But do we maximise our learning potential when we attend big international conferences? Let’s think about it. We arrive at a conference; if it’s an international conference we may be a little jet-lagged. We meet with colleagues travelling to the same conference, possibly in a bar, where we might consume a more than moderate about of alcohol; go to bed in our hotel and either sleep poorly because of the jet-leg or have no REM sleep because of the alcohol. The next morning we wake up early to attend the conference, still jet-lagged, tired, not at our best, where we sit through amazing talks and workshops. We then maybe attend a conference dinner where we stay up late, maybe consume more wine than we should – eat, drink, sleep, repeat – Do you see where I am going with this?
Alcohol is one of the most powerful suppressors of REM sleep that we know of.Walker, Matthew. Why We Sleep (p. 82). Penguin Books Ltd. Kindle Edition.
Now of course you are still going to learn loads and be inspired by attending a great conference, but we pay all that money to listen to amazing clinicians or medical educators and when we get there we are not maximising our learning potential. Thank god for Twitter and podcasts.
Another issue is the timings of teaching session. Scheduling any teaching at 09:00 disadvantages 30% of learners, even before allowing for the fact that many healthcare professionals go to ‘mandatory’ teaching before or after a night shift, or on a zero day when we should be resting. Insisting people lose sleep to learn is counter productive – it this day and age there are better ways than this ridiculous insistence that trainees have to endure.
Improving your own sleep
Let’s not pretend that if we are a habitual six-hour-a-night sleeper we are going to change to an eight hour a night sleeper overnight (we should, for the sake of our own learning, performance and health, but we won’t) but there are somethings we can do…
Try getting a little bit of extra sleep a night, even if it’s just half an hour extra – every little will help. I habitually used to get less than 7 hours sleep a night… Now I try to make sure I get 7, and if I am doing something important, I’m aiming for more. If you’re revising, you shouldn’t sacrifice sleep for revision… It’s not worth it.
Try taking naps. I’m not talking about naps to catch up on sleep because we were burning the candle at both ends last night, but naps following learning. These have been shown to improve fact-based learning by up to 20% (attention remained the same). Naps of as little as 20min can give an advantage as long as they contain enough NREM sleep.
Turn on the ‘do not disturb’ function on your phone for the time you are supposed to be sleeping so you won’t be disturbed by social media pings.
But I can’t get to sleep earlier
If we’re have trouble sleeping then laying off the coffee in the afternoon could help as caffeine has a half-life of 5-7 hours. Switching to decaf might be better but even that still contains 15-30% of the caffeine of regular coffee (about the same as tea).
Maintaining darkness throughout the night is important… Invest in some blackout curtains.
iPad reading delayed the rise of melatonin by up to three hours, relative to the natural rise in these same individuals when reading a printed book.Walker, Matthew. Why We Sleep (p. 269). Penguin Books Ltd. Kindle Edition.
Blue light from devices and LED lights play havoc with our body clock as it suppresses the rise of melatonin by up to 50% – it makes your body think it’s daylight. I am not suggesting for one minute that we all go back to living in caves (or even the early 2000s), but there are things we can do to help. Do not use every light in the place to illuminate your rooms in the evening; mood-lighting is the order of the day. Install or activate the software on your device that will gradually desaturate the LED light omitted over the course of an evening.
[For more info on sleep hygiene read Nat’s (@_NMay) post here and to download the free StEmlyns eBook The Resuscitationist Guide to Health & Wellbeing CLICK THIS LINK which will take you to the iTunes Store]
This is a simplified overview so I would highly recommend reading this book to get the full picture. Not only for the knowledge about sleep and learning but also life-changing information about sleep and health.
If you don’t snooze, you lose.
Walker, M. P. (2018). Why we sleep: unlocking the power of sleep and dreams. London UK: Penguin.