Sleep: A Complete Guide

Sleep is the foundation of everything we do... how we store memories, how we solve problems, how we recover physically, how we process emotions, how we 'cleanse' our brain, how we re-generate our cells, how we grow... literally everything stems from sleep, be it good, or bad.

This blog is not going to be short.

Sleep, and more importantly, our Circadian Rhythm, is one of my favourite topics. I have been lucky enough to spend time, work with, and learn from Sleep and Circadian Rhythm professors and experts based within Oxford University, authors and conductors of numerous sleep studies, and now I am able to apply my learnings to my client base (and anyone else who will listen).

Let's begin. At our very core, at our deepest level, our biology is governed by our very own 24-hour internal clock that advises us when it's the best time to sleep, eat, think, and to do a myriad of other essential tasks. Without the precision of our biological clock, our entire biology would be in chaos.

This internal body clock is called our Circadian Rhythm (Circa means 'about', dia means 'a day').

Our bodies need the right amount of materials (energy, hormones etc), in the right amount, at the right time of day. Our body clock anticipates the approaching day, prepares our body, so the new environment - the new day - can be exploited. This dates back to our hunter/gatherer days when we needed to be ready, quickly to...hunt and gather.

An hour or two before we wake, our blood pressure and metabolic rate increase, along with a plethora of biological processes to ensure we are ready to perform upon waking. A poorly adapted body clock (due to poor sleep, poor habits) would slow us down incredibly from the sleep state to our wake state.

In Greek mythology, Hypnos is the God of sleep. He is the son of Nyx (night) and Erebus (darkness). So we can see, in ancient times, sleep was likened to darkness and hell. We now know this is total opposite - it is where we grow and rejuvenate.

So, we know, a good night sleep is important. But how does sleep actually happen? And, what happens, while we are sleeping?

Our Circadian Rhythm drives us to wake. But then we have an opposing force, called Sleep Pressure, which builds from the moment we wake and is highest in the evening. Essentially we fall asleep when Sleep Pressure outweighs our Circadian Rhythm drive for wake. We then, naturally wake when sleep pressure diminishes and our circadian rhythm tells the brain it's time to wake up. We can train our circadian rhythm to wake us and work effectively for us. More on that later.

Once we are asleep, we stay alive by utilising stored energy. The energy is used to drive many essential activities and processes, including body tissue repair and removal of toxins that build up in our body during activity. We also generate ideas, solve problems, process emotions, and form memories. On top of that we build metabolic pathways and re-equilibriate energy.

Sleep goes through three NREM stages (Non Rapid Eye Movement) from a lighter state, all the way through to Slow Wave Sleep - SWS - then on to stage 4 - REM (Rapid Eye Movement) sleep. During NREM stages of sleep, we solve problems and form memories.

During SWS and REM, we recover physically. We wake naturally from REM sleep. If you've ever been woken by an alarm and feel dishevelled, wondering where you are, chances are you're woken from NREM stages of sleep.

The REM stage of sleep is where we dream - lack of REM sleep is linked to daytime anxiety, irritability, aggression. Hence dreams and REM sleep help process emotions and emotional memories. REM sleep is our brain putting our emotions in order and that often comes out in the dreams we have. Interesting fact! During REM sleep we experience paralysis from the neck down. This is to stop us acting out our dreams and causing ourselves, and others around us, harm.

After moving through all cycles of sleep, our circadian rhythm tells us to wake. Sleep defines our ability to operate when awake. Lack of sleep impacts hugely our health and wellbeing...

*One important thing to note is, in five years of training, medical students will only take 1 or 2 lectures on sleep / circadian rhythm. So blogs like this or books on the subject are often extremely beneficial to learn from.

Health Implications from poor sleep: When we are tired we produce more Cortisol (the stress hormone). Cortisol raises inflammation in our body and also breaks down collagen, which can lead to puffiness and water retention. Our circadian rhythm increases cortisol in readiness for the new day. It declines in the evening. Cortisol anticipates our demands for sleep and wake. If we become stressed, then cortisol release overrides our daily sleep/wake pattern.

Short term cortisol release is beneficial for fight or flight but harmful long-term, impairing our health & performance. The problem with long term stress is the emergency response is switched to the 'on' state for long periods and is unsustainable.

The link between lack of sleep and cortisol release is also important if we are trying to lose body fat/weight. Increased cortisol raises blood sugar levels. Cortisol opposes the release of insulin which removes glucose from circulation. This leads to more glucose in the bloodstream – again, useful for fight or flight – but unused glucose is then stored as fat around the abdomen. Cortisol also alters our appetite and increases cravings for high calorie, sugar-rich foods. Not good for a lean body.

High levels of cortisol also prevent us from retrieving memories – think of when we’ve had a test, we can easily forget what we have learned. Our immune system is also suppressed from long term exposure to higher cortisol levels.

*A study done over six nights allowed a group to sleep for only 4 hours a night. After six days, cortisol levels were markedly higher, particularly in the afternoon/evening when they should be dropping.

So inadequate sleep - defined as 7 hours or less - has many health implications, just from elevated cortisol alone.

The tendency towards depression increases with poor sleep and not being aligned with our biological cycle. Add that to the list above, plus increased aggression, irritability and anxiety, we can see we ignore our circadian rhythms at our peril.

How to set our internal biological clocks for the better: There is a great system we can use, called Entrainment. There are certain things we can do, on a daily basis, to help us go to bed in sync with our circadian rhythm, sleep better, and wake up refreshed.

Sunlight is the most powerful factor for entrainment. Particularly dawn and dusk light. Light exposure in the early evening will delay our circadian clock = we go to bed later and

wake up later the next day. By contrast, morning light will have the opposite effect, helping us go to bed earlier and wake up earlier. So, in the morning, as soon as possible, by getting some sunlight exposure - in the eyes (you dont need to stare at the sun, merely be exposed to it) this will set your system to want to sleep earlier and wake earlier.

Sunlight is hugely advantageous over artificial / indoor lighting. Light is measured in lux. After dawn there is 2000-3000 lux of light compared to 100-400 at home or the workplace. By noon it can be 100,000 lux outside. There really is no comparison for natural light. Even light coming through a window isn't as beneficial as being outside. It's about half as strong, generally.

*A U.S study, camping in the Rockies, looked at how one week of morning light exposure changed the wake up/go to sleep pattern by TWO hours compared to those with electrical lighting. So the 'natural lighters' went to sleep and woke up two hours earlier than their counterparts.

Could we entrain ourselves to become nocturnal? The simple answer is no. Studies show that 97% of night workers remain synced to daytime. This is due to daylight exposure - we would need to be totally shielded from daylight. This isn't feasible for most night shift workers. One study did, however, expose night workers to 2000 lux of light at night and totally shielded them from natural day light – they became nocturnal. However, if we are exposed to any daylight, we will always remain synced to ‘daytime’.

Employers assume night shift workers will adapt. This is wrong. Employees can become dangerously ill, overweight and mentally impaired and a higher risk of road accidents.  There is so much evidence to support this.

Fact! After the clocks change in spring time, studies have shown a 4% increase in road accidents, given to more morning tiredness and our circadian rhythms not adapting to new 'time'.

Exercise and eating times can also affect entrainment. Exercise earlier in the day has been proven to aid earlier sleep at night and an earlier wake up the following day. Conversley, exercise in the evening releases adrenaline, which will keep us awake longer. Our body literally anticipates what is coming, going by what we have done over the last three to four days. If you want to become more of a morning person, expose yourself to early sunlight and morning training sessions, and in three to four days, your body will anticipate more of it, and prime you ready for the day. That's two invaluable tips so far for a better nights sleep - early exposure to sunlight, and exercise early in the day.

By eating later in the day, our stomach and digestive system are processing food, when we should be trying to calm everything down. If your target bed time is between 10-11pm, it is suggested we finish eating by 7pm at the latest, to allow for full digestion. This tip is also helpful for people wanting to lose belly fat - unused energy from food is stored as fat around the abdomen. So stop eating by 7pm latest for better sleep and body composition. A gentle walk would be great after your last meal too, nothing strenuous, just 30 mins, at a slow pace.

How else can we prepare for a great nights sleep? Limit phone, tablet and computer use 30-60 minutes before bed. But not for the reason you think, possibly. Most people believe the light emitted keeps us awake - this has not been proven. Mobile phone use at night increases alertness in the brain leading to daytime sleepiness. It's the alerting effect that is the problem. If we can replace screen time with some stretches, a book, or quietly going over our day, we would fall asleep much quicker.

A cool room, is beneficial for a good night sleep too. The body has to drop its temperature to allow us to sleep. This is also the reason why a hot shower or bath before bedtime helps us sleep better - the cooling effect after the shower releases sleep inducing hormones, 20-30 minutes afterwards, making it ideal for better sleep.

Melatonin: good or not so good? Most of us hear the word melatonin and automatically think it helps us sleep. Research is very mixed on this to say the least, stating melatonin is not proven as ‘the sleep hormone’. Bright light prevents melatonin production, so being careful with this before bedtime should be considered. Also, by taking melatonin supplements at the wrong time can confuse our circadian rhythm and blunt the effects of light, leading to worse sleep! For help sleeping, we should always apply the practices stated throughout this blog before reaching for the melatonin supplements.

Many long haul pilots, flight attendants and travellers use melatonin to go to sleep in the new time zone, but entrainment via sunlight exposure is our best bet to adapt and sleep well as soon as possible. General Rule – if you travel west from the UK seek out light ASAP as our clock needs to be delayed. If you travel east seek out light later in the day as their clock is ahead and you need to advance yours. Calculate when it is dawn and dusk in your new time zone then aim to seek or avoid daylight to delay or advance your clock for the first few days. Eating at local times will help too.

*An interesting study on long haul flight crew revealed smaller temporal lobes – affecting memory, reaction times & cognitive function over long periods. Flying for 6-7 hours, through different time zones, our circadian rhythm simply cannot adjust quickly enough.

Caffeine: Coffee and caffeinated drinks are ok, again, earlier in the day. If we can stop caffeine ingestion (coffee, tea, coca cola & other energy drinks) by 2pm, it will have a positive effect on our entrainment for better sleep. A hormone called Adenosine makes us feel sleepy - caffeine blocks receptors which detect adenosine, preventing the brain from detecting how tired it actually is.

So there we have some tips for better sleep and being aligned with our circadian rhythm, which in turn leads to better health, performance and wellness - something we all strive for. If anybody has any questions on this topic, I welcome them, please contact me via my website.

I am also available to discuss this topic in Spain and in the UK, as part of my work as a fitness and health expert.

Thank you for reading! Iain