The only person who knows exactly how much sleep you need is you. We find that around eight hours is the magic number for most people. Evidence suggests that too little (less than 6.5 hours), and too much (more than 8.5 hours) sleep can have negative health implications. We have a ball-park for what constitutes an optimal amount of sleep, but as with nutrition, movement - and pretty much everything health - so too, sleep is an individual experience.
The secret is to find your sweet spot; which may change over time.
The sleep ‘sweet spot’ will be affected by your genetics, but also your state of health, age, and your physical and emotional stressors. To optimise, my recommendation is to regularly get as much sleep as you naturally would while on protracted relaxing holidays.
Every now and then you can ‘getaway’ with less sleep, just don’t let this become the norm and kid yourself that you won’t pay for it later. As we prior learnt (here), skipping out on sleep can have dire consequences, so at this point, we’re going to assume you already know this and just want to learn how to optimise... read on.
Sleep is not just about duration, but also: quality. The first being reasonably straight-forward, the second… less so, and frustratingly elusive for many.
Quality sleep is a tale of two hormones: melatonin and cortisol.
The pineal gland (in your brain) produces melatonin (your ‘sleep hormone’). It does so according to several factors:
Your sleep pattern/behaviour and exposure to light both dictate how much melatonin is produced.
Melatonin is naturally produced in wave-cycles of around 90 minutes (which correlates with a natural sleep cycle). If you have ever experienced overwhelming sleepiness, and then found your ‘second wind’ shortly after, you have just experienced the peak of your melatonin wave, followed by a tapering off, and now you are set to avoid sleep again for another hour. Conversely, you may have experienced being sleepy and setting off to bed, only to find that after you have brushed your teeth and pottered around for a few minutes, once in bed, you are wide awake… oops you missed the melatonin wave!
The human body – being an adaptation machine – has a system that allows us some variance to our sleep patterns; enter cortisol.
Our adrenal hormone cortisol – like melatonin – is regulated by our circadian rhythm, but otherwise has an opposing effect. Being our ‘survival hormone’, cortisol is profoundly affected by stress and busyness. When cortisol levels are high at inappropriate times (usually due to stress), melatonin is overridden and unable to do its job, meaning sleep is difficult to find or maintain, despite us desperately wanting it. The experience: ‘tired but wired’.
Think of melatonin and cortisol as sitting on opposite ends of a see-saw – when one is up, the other is down. It’s important to understand that lifestyle stress impacts on cortisol levels, and therefore negatively impacts melatonin.
With melatonin levels at their wave-peak, it is enough to overcome cortisol. Still, as melatonin levels drop, the cortisol again provokes wakefulness, until melatonin peaks again and the cycle continues. The experience: ‘waking hourly’.
To understand how good sleep quality is found, we simply need to look back to our ancestors.
The time we are most productively active is during the day, with warmth and light. As the light fades, we gather around the fire to eat and tell stories, as is our custom. With nothing more than a fire, or a strong moon, to provide light after dark, not much to do or worry about, and limited clothing to ward off cold, we are best to seek shelter, huddle, cuddle and sleep, during the coldest, darkest portion of the daily cycle.
The seasons change slowly and so, therefore, does a change in useable daylight; the time the sun goes down tonight will be indiscernibly similar to last night, and thus the time we sleep will likely be similar too. We don’t experience jetlag; jets don’t exist… you know, what with them being cavemen and all.
Given a natural environment, quite reasonably, the body presumes:
Like most systems it is elegant, given the environment it evolved in, and therein lies the problem.
We have now mastered warmth, travel, and light, and are no longer subject to any daily rhythm other than that which we choose to conform to. Thus, there is little in the way of strong signalling to our body that sleep is approaching, or even imminent. Instead, we choose when to sleep according to our whim, often giving our body no prior indication.
Meanwhile, the stress in the modern world is very rarely an issue of survival, being more-so and ever-increasingly just a by-product of busyness; the way we live our lives. The expected short-term stress variance the body is experiencing never goes away, and thus we find it hard to re-calibrate to normality.
Yet - despite the clearly dramatic departure from our evolutionary norm - our genetics have not changed; we’re still running the same ancient sleep architecture. Our body doesn’t know that busy is the new normal, or that light is on a switch, it just seems confused signalling with a lack of pattern; poor sleep hygiene.
The solution for good sleep regulation, therefore – perhaps unsurprisingly – is with good sleep hygiene, which comes down to habit, and expectation.
If you have ever spent much time around a little one, then you probably know of the sleep magic that is: dinner, bath, book, bed. A predictable sequence of events that is focused on the parasympathetic nervous system – rest, digest, repair. Somehow we recognise that routine works for kids, but you know who else it works for? Humans. Adults aren’t any different.
Simply let your body know that sleep time is coming (a predictable sequence of parasympathetic focused events). After it learns to read your messages (gets into the habit), it will begin winding down so that you can sleep. The keys here are in letting your body know when sleep is coming (increase melatonin), and allowing yourself to wind down (decrease cortisol). If you maintain good sleep hygiene as according to habit, your sleep cycle will fall in to sync. This is ‘the way’ of sleep.
Sleep has been a critical part of survival for all of our species evolution. To expect that suddenly we don’t need it in the quantity or quality of our ancestors is a fast-track to poor health. So be prepared to let go of FOMO, and… go to bed!
It may take 2-4 weeks before your body learns to read your new sleep signals, so I encourage you to be patient and continue with it until this new habit sticks.