Health Part 2: Sleep
The second of our three Fundamentals of Health is sleep. Often the first thing to be sacrificed at the altar of stress or socialising, the impact of sleep on both positive outcomes for good practices and the negative effects of neglect cannot be overstated.
With a body of research that has been rapidly growing over the past decade the importance of good sleep on Health and Fitness is beyond doubt, with "Increased sleep duration independently associated with a reduced risk of in-season injury... even after adjustment for training load and subjective well-being. The effects of mood, fatigue, and stress on injury were no longer evident after adjustment for the effect of sleep duration." (PubMed ID 33225012)
In order to understand how to organise our nocturnal habits we must first break down the different phases of sleep, how they’re sequenced, and how to access them. There are three main phases that characterise the different depths of sleep.
Light sleep
This is the shoreline of consciousness and unconsciousness. As we progress through this stage of sleep the electrical activity of our brain shifts from wakeful Beta waves to slower Alpha waves.
In this phase we’re easily woken up, and the longer we’re undisturbed the more our muscles relax. We drift in and out of this phase over the course of the night, mainly to change position to prevent discomfort and muscle cramps.
Most importantly, when we wake in a light sleep phase we feel fresh and alert. If our alarm goes off in the deeper phases we feel groggy for 45mins or so after waking, even if we’ve had adequate amounts of sleep.
REM sleep
So called because of the Rapid Eye Movement that characterises it, this phase sees brain activity reach near-waking Alpha wave levels in a specific brain region called the Occipital Lobe.
Our muscles relax and we’re no longer conscious, so our brain activity is expressed to us as dreaming. Interestingly if we’re sleep deprived we can enter this phase too quickly, and as our body isn’t quite relaxed we act out the dream, twitching ourselves awake.
This phase affects our psychological tolerance to training, as well as emotional regulation, cognitive function, and memory.
Deep sleep
Characterised by Delta wave electrical activity, this phase has neither dreaming nor physical activity and is where we experience the greatest amount of physical restoration, with the release of various hormones stimulating muscle repair and immune system function, as well as leptin and ghrelin, hormones that suppress and increase appetite, respectively.
Taken together these phases amount to one sleep cycle of around 90mins, but the composition of each cycle varies through the night.
In the first cycle there is a greater amount of light sleep as we transition from wakefulness.
The first two cycles see us spend the greatest duration in deep sleep, drifting from light sleep straight into the deepest phase, then back to light, and repeating the cycle once more.
From cycle 3 we no longer drift to the deepest phase, but between light sleep and REM sleep, with the duration of REM sleep making up more and more of the cycle until we wake. This is important to note, as shortened durations of sleep means we miss these later REM-rich stages, which has a cumulative effect.
We encourage getting 35 cycles per week (More on tracking cycles per week vs hours per night below), which amounts to 5 cycles of 7.5hrs of actual sleep per night. A weekly prescription allows us to catch up on missed sleep, a realistic proposition for most people. It also allows us to plan ahead; if you know you’re going to have a night or two that won’t allow you to get enough sleep you can add the anticipated cycles to other days and sleep more ahead of time to build up a buffer to get through it, as well as a catchup period afterwards if necessary.
The most common recommendation is to get 8hrs of sleep per night, which largely lines up with 5 cycles per night once actually getting into bed and transitioning from wakefulness to sleep is accounted for.
8hrs is, unfortunately, most frequently translated to 6-7hrs, because it’s close enough, isn’t it? And we all think of ourselves as the exception to the overwhelming body of scientific evidence. Except we’re not.
In 2009 a clinical trial saw participants first become sleep saturated for three days. No alarms, they slept for as long as they needed. Once saturated they performed some cognitive tasks; timed language and mathematics exams, abstract problem solving. They were asked how they felt on waking and how they felt they’d performed after testing.
The majority of participants actually settled on 9hrs sleep, although when participants were woken up after 8hrs they suffered no ill effects; their performance on the tests remained in the same range, which was reflected in how they felt they’d done.
The next stage of the study had the participants woken up after 6hrs, or 4hrs of sleep. As one might expect they reported feeling tired, performing poorly, and this was reflected in the test results.
Most interestingly, however, after 2-3 days of 6hrs sleep participants reported feeling less tired, that they felt that they had adapted to their new sleep schedule; they felt better and their self-reported performances on the cognitive testing went up, claiming their “adaptation” allowed them to perform better on 6hrs or 4hrs sleep. But they didn’t. They only felt like they did. Their actual performances stayed at the impaired level, they simply convinced themselves that they had adapted and improved.
Around 1% of the population have a genetic mutation that means they genuinely require less than 8hrs sleep. That means that right now maybe one member of the gym has this capacity. And I bet you at least half of the people reading this think it’s them. Yep, you and everyone else…
Setting Up for Sleep
A good night's rest actually starts at around midday, which is the latest that we should consume caffeine as it has a half-life of 12hrs, meaning that a cup of coffee at midday has a similar effect to consuming half a cup at midnight. There are broad genetic differences in response to caffeine but the mean is a good place to start.
Caffeine blocks adenosine receptors in the body, a sleep-inducing compound that builds up through the day and is cleared from the body during sleep.
A common response is that "Caffeine just doesn't affect me", in truth an echo of the above perception of how we imagine our capacity to function on less than adequate sleep, nothing more than a story we tell ourselves.
Very often these same people also claim to not be able function without caffeine throughout the day, meaning that they are a responder. The two claims contradict one another, either caffeine doesn't affect you, in which case you can go without it, or it does affect you, in which case consuming large amounts and late into the day disrupts your sleep. Being dependent on something and building up a tolerance to it is not the same as being a non-responder.
Even if you have no trouble falling asleep, caffeine will ensure that you won't get as much Deep and REM sleep, reducing the quality of rest even when in bed for an adequate duration.
If you consume more than three cups of coffee a day and/or consume it well into the afternoon you're in need of an intervention more than most. Try replacing coffee late in the day with tea, which has less caffeine and also contains L-Theanine, a sleep promoting compound.
Proximity and amount of alcohol before sleep is a similar consideration but at the other end of the spectrum. Where caffeine is a stimulant, alcohol is a depressant. Because of this we often think we're recovered because we spend more time in bed, but sedation ≠ sleep, and the majority of that time is spent in the lighter phases of sleep, punctuated with trips to the bathroom depending on the individual.
These effects are not linear, either, acting more like compound interest once two drinks are passed. That said, depending on our habits the "one or two" drink nights can often be the most insidious, as they tend to happen more frequently, we don't feel drunk, but suffer many of the ill effects of a larger dose of alcohol.
We can mitigate these effects by cutting ourselves off prior to sleep. It takes around 1hr to process 1unit of alcohol, so keeping an eye on our overall volume and leaving 2-3hrs between your last drink and bed will limit the effects.
To be clear, we're not anti-alcohol or caffeine at all, we just want everyone to be fully informed about the effects. When we stopped having a glass of wine at the end of the day we found we recovered much better, had far more mental clarity and on reflection didn't really need the wine, it was simply a habit, but one which chipped away 1% at a time, unnoticeable but significant.
Challenging the behaviours that exist simply because we don't pay attention to them, or worse wilfully deny their effects, leads to all of our habits pulling in the direction we want to go instead of feeling like we're doing all the right things but getting nowhere e.g. spending 8-9hrs in bed but still feeling tired because we had a coffee at 1pm and a glass of wine before bed.
We can also use this knowledge to accept the consequences of our social lives, making a conscious effort to get to bed early after a big weekend until you're back on track, or even getting more sleep leading into those events.
Having covered common sleep disruptors, now we need to ensure we're actually getting enough sleep, and a great place to start is to work back from your alarm. If our alarm is set for 6am we work back in 90min cycles to find our ideal bedtimes (Note that the diagram below sets a wake time of 7:30am, but the principle is the same):
4:30am-3am-1:30am-12am-10:30pm-9pm-7:30pm
Working with our sleep cycles in this way ensures our alarm goes off around our light sleep phase. An even better intervention is the Sleep Cycle app, which wakes you within a 30min window when your phone microphone registers movement. Movement = light sleep, light sleep means waking up feeling fresh.
For my schedule the 9pm or 10:30pm times work best, meaning I have to start getting ready for bed 30-45mins prior, being in bed and ready to sleep at that time.
Use this time to put your phone away (The ill-effects of phone use in bed is beyond the scope of this post, and if you're not already sold on this nothing I write here will tip the balance), if you use it as your alarm put it on do not disturb/airplane mode, and make any preparations you need for the next day. This is especially useful if you find it difficult to sleep through overthinking, making a list clears your head because you know you'll see to your to-do list the next day.
Eye masks to block out light and ear plugs to reduce sound can be really helpful for staying asleep and accessing deeper phases for longer. The mask pictured below is AMAZING as the cups prevent the mask pressing down on the eyes/eyelashes and they block out all the light. Click here for the ear plugs we use.
There are many supplements that claim to improve sleep. The only one that we strongly recommend is Magnesium Threonate, which we've found helps us to fall asleep more easily, stay asleep longer and get more deep and REM sleep. We use a fitness tracker that gives us data on sleep phases and the difference to our restorative sleep has completely sold us on the efficacy.
It's important to note that while you may have experimented with other forms of Magnesium previously, the most common forms (Bisglycingate and Citrate) have a bioavailability of around 8%, whereas Threonate is upwards of 30-40%. Again, the difference we've experienced is notable. We use Time Health and you can get a 15% discount using SHIROKUMA15
For further reading we recommend:
A thorough look at sleep phases and the effects beyond Health & Fitness. It can sometimes be a bit heavy handed in parts, for example he is very rigid about claims that you can't catch up on sleep and therefore most of us are headed for dementia, but overall it's a good read and well researched. The effects of caffeine and alcohol mentioned above are from this book.
Lesser known but much more practical, Littlehales is a sleep coach who has worked with many top athletes and sports teams. As such his recommendations are more applicable to the realities of life, socialising, parenting, travelling; in the same way that players have little say over kickoff times and post-match press conferences, there are many things that we can't control. The idea of counting sleep cycles not hours, as well as the bedtime recommendations, are from this book.
Sleep well, and if you’re a member we’ll see you next week. If not, hit “Book Free Intro” to get started.
