For someone who has run their own businesses for more than 30 years - burning the candle at both ends - researching how much sleep we require has had a profound effect on how I now live my life. Those who know me well will be astounded by what they read here.

There will always be periods in everyone’s lives where - due to external factors such as work, having young children or even party season - getting a good night’s sleep becomes a low priority. While the odd day or two of not getting enough sleep shouldn’t cause any long-term health problems, sleep deprivation over a sustained period can be very harmful. I personally found the views I am about to share with you very hard to swallow. For the past quarter of a century I have preached that the early bird catches the worm; that while you rest you rust; that I will sleep enough when I’m dead - and a number of other one-liners that in the main suggest that life is just too short to sleep. What I have now learned from in-depth conversations with several of this book’s contributors, is something very different indeed, and that the theory that ‘life’s too short to sleep’ is incorrect. It should be restated as, ‘life is cut short without sleep’.

It is really important that we don’t confuse rest with sleep, as they are two very different things. While resting for a few hours on the sofa watching a movie might help us de-stress and unwind, it does not allow our body to go into repair mode. It does not allow the brain to process its learnings from the day or let our various hormones get themselves organised.

Dr Shan Hussain 

Dr Shan Hussain

One of the most common complaints I hear from patients is, “I’m tired all the time.” On occasion, there may be medical causes for this, but the vast majority of the time the solution is very simple: sleep more, and then review your energy intake and expenditure.

Our Circadian Clock

In September 2017, American scientists Jeffrey C Hall, Michael Rosbash and Michael W Young won a Nobel Prize for their work on the internal clock of living organisms. Today, our internal biological timepiece is referred to as the circadian clock (pronounced ‘sir-kay-dian’).  

We have already mentioned the stress hormone cortisol, and how it can wreak havoc in our body if it not controlled properly. It turns out that, if we don’t get enough sleep at the right time of night, then as well as keeping ourselves awake we also rouse our cortisol monster. To explain why this happens we need to learn a little about our circadian clock.

Way before the British invented the grandfather clock and the Swiss perfected the wristwatch, Mother Nature beat them to it by creating the body’s circadian clock. It doesn’t need winding up or batteries but keeps time primarily by the rising and setting of the sun, which activates a hormone in our body called melatonin. Nature didn’t create the circadian cycle (often referred to as the biological rhythm) exclusively for us humans, but for every living thing on the planet – from animals to fish, plants to microbes. Understanding the cycle is extremely important to our health, so much so that in the 1980s a whole new field of science was created to study it – chronobiology.

circadian clock

For those of us who live a distance from the equator, our body has to adapt to huge swings in the hours of sunlight that we receive throughout the different seasons. In the UK, during the darkest winter days, we get as little as eight hours of sunlight, but in the middle of the summer we receive a whopping 16. With our circadian clock being regulated by sunlight, it’s a good thing that the change happens subtly, with sunrise and sunset changing by approximately just one minute each day.

Remember that what keeps our biological clock in sync is sunlight. The chart on the following page is based on the sun rising at 6am and then setting at 6pm, as it does mid-spring and mid-autumn in the UK - and pretty much all year round near the equator. At other times of the year, as the hours of sunlight move backwards or forwards by only a minute or so each day, our circadian clock is able to fairly reliably reset itself.

Let’s look at our 24-hour clock, starting at midnight, give or take 30 minutes:
  • 00:00 To make sure we feel tired, melatonin production reaches its peak around midnight. The thyroid gets to work and tells the mitochondria in our cells to burn energy to keep our inactive body warm. This is how we lose weight when we sleep properly.
  • 01:00 Melatonin slows down our brain activity so that we can process what we have learnt in the day and form long-term memories.
  • 02:00 Our deepest sleep, where the body starts to enter repair mode.
  • 04:00 We are at our most relaxed at this time, and both our neurological and immune systems are hard at work.
  • 05:00 It takes five or six hours of sleep for our body to reach its lowest temperature, this is why it’s nonsense to get less than seven hours sleep.
  • 06:00 We get a surge of cortisol and blood pressure rises in an attempt to wake us, and the brain mobilises our muscles.
  • 07:00 The body stops producing our sleep hormone melatonin and switches on our hunger hormone ghrelin.  
  • 08:00 Our bowels become active and if we ate the day before they stir action downstairs.
  • 09:00 The height of testosterone secretion for the day.
  • 13:00 The most alert we will be all day.
  • 14:00 Height of co-ordination (so we could track animals after the midday sun).
  • 15:00 Fastest reaction times (so that we could catch said animals).
  • 17:00 Maximum muscle strength and cardiovascular efficiency (in case we didn’t catch an animal the first time).
  • 18:00 Highest blood pressure of the day. As long as we are on a low CARB diet, in order to stop us eating too much, leptin will continue to rise until it’s time for sleep. If for some reason it doesn’t, then for goodness’ sake don’t eat CARBS, but try some coconut or avocado instead.
  • 19:00 Peak of body temperature.
  • 21:00 The body starts to produce melatonin to tell us we are tired and ready for sleep.
  • 23:00 So that we are not going to the toilet all night, our gastrointestinal works start to go to sleep.

Until a few years ago, both of my two youngest daughters, Jessica and Lili - used to always sleep with their bedroom lights on. I tried everything to get them to sleep in the dark. I taught them about our biological clock and how, if they kept their lights on, or left their iPads and iPhones blinking all night, how they wouldn’t produce enough melanin - and without it they wouldn’t get smarter at school. But it all went in one ear and out the other. Then I remembered a two-word phrase that everyone has heard. I reminded them that, as well as feeling healthy and improving their intelligence, if they turned off their lights, they would become even more beautiful than they already were. I simply told them that it’s called ‘beauty sleep’ for a very good reason, but it only becomes real beauty sleep when the room is totally dark. Any light in the room at all and the magic just doesn’t happen!

The saying ‘beauty sleep’ is based on the fact that, while we sleep, our skin regenerates itself up to eight times faster than when we are awake. We all want to look more beautiful, but let’s look at what happens on a less superficial level. While we are asleep:

  • The body goes into repair mode and increases our growth hormones
  • The brain assembles the jigsaw puzzle of knowledge that we learnt during the day
  • The brain takes the daily knowledge and stores it neatly into our mental filing cabinets, so that we can more easily retrieve and recall it in the future
  • The liver doesn’t have to deal with incoming food (it’s difficult to eat when we are asleep) so gets to work detoxifying our body
  • The body increases the production of testosterone

Without Sufficient Sleep

  • Knowledge and memories from the day’s activities become scrambled
  • The body struggles to regulate our body temperature, and becomes particularly inefficient at dealing with extreme cold or heat
  • The body creates an excess of cortisol, and we become easily stressed. Have you noticed how short-tempered we become after a poor night’s sleep? It’s not our fault that we become irritable and ratty, it’s an excess of the hormone cortisol
  • Our immune system begins to fail
  • Insulin struggles to regulate blood sugar levels, and a lack of sleep over time can lead to type 2 diabetes
  • Leptin and ghrelin hormones don’t function properly, leading to overeating
  • Our body can lose control of its fight with inflammation

Waking up happy

For years, I limited how much sleep I got because I thought it made me a better person, a smarter businessman, and because I believed it gave me more time to achieve things. Yet it turns out that, while I had a feeling of self-righteousness by getting out of bed at the crack of dawn, I was actually becoming a weakling by stopping my muscles from growing properly. I was becoming dumber by not allowing my brain to properly organise what it was learning, and I was killing my sex drive by not producing sufficient testosterone. Putting on my running shoes at 5am, feeling like the smarter martyr who was getting fitter than the rest of the population who were still in bed sleeping their life away, it was actually counterproductive - and rather than improving my overall health, it was actually impeding it.

How Much Sleep Do We Need?

There is no simple answer to this question as we are all different. The more active we are, the more sleep we potentially need. I also believe that it can vary a little from day to day. I personally sleep around six to eight hours during weekdays and get between eight and nine hours a night at the weekend. So, what do experts recommend? The National Sleep Foundation of America recently assembled 18 leading scientists and researchers and gave them the task of bringing their official recommendations up to date. As of June 2017, this is their suggestion:


Recommended sleeping hours by age

While we also have similar guidelines in the UK, the US study is so well researched that I personally prefer their findings.

It might be true that politicians such as Margaret Thatcher got by on four hours sleep each night, just as Donald Trump also claims to only need four to five hours, but is that actually good for our health? The simple answer is no! Researchers at the University of California in San Francisco discovered that 3% of people have a gene that enables them to perform well on just six hours sleep per night. But for the other 97% of us, in order to live a healthy, happy and long life we need to follow the above recommendations.

Dr Dan Maggs 

Dr Dan Maggs

You need as much sleep as you need! Don’t try and cheat it else it will catch up with you eventually... somehow.


Deborah Colson MSc 

Deborah Colson

If people are eating a diet which is high in sugar and refined carbohydrates, it can affect their ability to sleep, because the brain can be a bit wired. Magnesium is a really key nutrient for sleep; it really helps the mind to calm and prepare for sleep, and there’s also an amino acid called taurine, which is really important to sleep. Taurine definitely has a very calming and relaxing effect. The main source of taurine is offal, for example heart, which of course most people don’t eat.

Chilling Out and Cat Naps

There is definitely a place for taking time to relax when living primally, but that does not mean we are endorsing the couch potato way of life. Without doubt we are living in the laziest, fattest and most sedentary era ever. Think about the progression. We used to hunt for food, then we had to walk to stores to carry home food, then we could travel to restaurants – and even this burnt some calories. But today we can simply go online and order any takeaway we desire.

In the UK there is even a food portal called Just Eat, which can now deliver us almost any junk food meal we desire. We then sit down, turn on our TV and scoff down our food without even registering we’re doing so. And remember ‘scoffin’ is only one letter away from ‘coffin’!

It would be perhaps naive to think that our primal ancestors were on the go from sunrise to sunset. What we believe is that we should get around seven to nine hours of quality sleep each night. If we aren’t able to do that during the dark hours, maybe because of work commitments or childcare, then we should try to make up our missing hours of sleep with a Spanish-like siesta in the afternoons.

Interestingly, on the Greek isle of Ikaria, where there is a high percentage of centenarians, afternoon naps are commonplace. Plus, the Harvard School of Public Health reported that just napping for 30 minutes, at least 3 times a week, lowered coronary mortality. Now I normally discard this type of research, as it is not derived from a controlled randomised, interventional study, but in this case the conclusion feels logical and it’s certainly backed up by the longevity of people in regions where naps and siestas are regarded normal.

Dr Emer Macsweeney 

Dr Emer Macsweeney

I think people are increasingly recognising that sleep is very important for brain health. Actually, often people do say that when you’ve got a stressful day or a difficult day the next day, sleep is actually your best weapon.


There is now an increasing amount of evidence that sleep is not just important in terms of regeneration in the brain, but also the removal of potentially toxic compounds from the brain that we create during the day. Also, the quality of sleep is important.


But if you can’t get a good night’s sleep, then even frequent 20-minute naps during the day are really excellent in terms of restorative influence on the brain. While we don’t understand it all completely, I think it is now just incredibly well recognised that sleep is very important for the brain.