‘Sleep is the single most important behavioral experience that we have.’ Russell Foster, Circadian Neuroscientist, University of Oxford.

A healthy lifestyle should place the utmost importance upon sleep. This cannot be stressed enough. Doing everything in our power to ensure a good night’s sleep is critical. Our diet and exercise may be perfect but if we are not getting the right amount of sleep on a consistent, long-term basis, problems will arise.  Improving our sleep can contribute to improving our health. Improving our health can contribute to improving the quality and longevity of our lives. They are inextricably linked yet why do we often find it so hard to make the changes that are needed?



In the UK, we sleep for an average of 6.5 hours per night which is inadequate. A third of people are getting just 5-6 hours sleep a night and only 22% have 7-8 hours sleep. Although 41% of people read a book before bed, 38% of people watch television in bed and increasing numbers of people are using electronic devices. Stress and worry keeps 47% of us awake at night. Nearly 8 million people are using alcohol to try to get a better night’s sleep and 7 million people are taking medication to help them sleep. (Statistics from The Sleep Council Report). These are worrying figures but what are the practical steps we can take to improve our sleep?



As always, we need to look to the ancestral model and try to adapt it the best that we can. We are ‘hard-wired’ to follow the natural rhythms of the world around us – winding down and sleeping as the sun sets and naturally waking with sunrise. However, in our modern world a myriad of external factors can disrupt this rhythm, leaving our mind and body confused, stressed and unable to function at its capacity.

Our circadian (‘around the day’) rhythm is a built-in cycle that regulates physiological and biological changes in the body. It is adjusted to external cues in the environment such as light levels, which are picked up by the brain in the hypothalamus. Chronic disruption of our circadian rhythm and sleep pattern has been linked to diseases such as diabetes, cancer, depression and heart disease as well as inflammation, high blood pressure, obesity, insulin problems and decreased immune function. Leptin and ghrelin levels are also disrupted, causing over-eating, cortisol levels increase, the list goes on and on…

In a natural environment, the day draws to a close and blue light decreases while red light increases. This triggers the pineal gland into the production of melatonin (produced from serotonin) which promotes sleep. As we sleep, our body temperature and heart rate decreases and blood pressure drops. Conversely at daybreak when light levels increase, our body temperature and cortisol production rise and melatonin production decreases to extremely low levels. As essential melatonin production is suppressed by blue light, controlling our sleeping environment and our exposure to blue light in the hours before bedtime is critical for a good night’s sleep.



In his excellent Ted talk (see link below) Circadian Neuroscientist Professor Russell Foster, University of Oxford suggests that one of sleep’s important functions is to facilitate important brain processing and memory consolidation. Professor Foster describes how the individual’s ability to learn a task is severely disrupted by sleep deprivation and how our ability to come up with novel solutions to complex problems is hugely improved with a good night’s sleep – in fact giving us a threefold advantage. Sleep may actually enhance our creativity.



Professor Foster explains how sleep deprivation leads to poor memory, poor creativity, increased impulsiveness and overall poor judgement. As well as this, he notes that a sleep-deprived brain leads to dependence upon stimulants such as caffeine and the need to sedate with alcohol, which gradually becomes less and less efficient leading to the need to consume greater quantities.

He adds that if you sleep 5 hours or less a night you have more than a 50% chance of being obese. Sleep deprivation gives rise to ghrelin – ‘the hunger hormone’ which encourages the brain to seek out carbohydrates. It also leads to stress and suppressed immunity and plays havoc with glucose levels.

With all of that, how do we know if we are getting enough sleep? What is too little? How much is enough? As always, listen to your body. Professor Foster suggests that if you need an alarm to wake up, if you are feeling tired and irritable upon rising, if you require caffeine to function, these are all signs that you need more sleep. Professor Foster’s research into sleep and mental illness is also very interesting – please listen to the talk for further information.


Dr. Thomas Wehr at the National Institute of Mental Health conducted a landmark experiment (see here) in which he placed a group of normal volunteers in 14-hour dark periods each day for a month. He let the subjects sleep as much and as long as they wanted during the experiment.

‘When a young woman slept in long (14-h) artificial “nights” (upper position of figure), her sleep expanded and separated into two 3-to-5-h bouts with a 1-to-2-h period of wakefulness between them, as was typical of many other individuals. When she slept in conventional short (8-h) artificial “nights” (bottom portion of figure), her sleep was compressed and consolidated, as is considered to be normal. Historical records (see text) indicate that before the Industrial Revolution, many humans slept “from sun to sun,” and sometimes in two bouts, like the woman in long artificial scotoperiods. Raster plot shows electroencephalographically monitored sleep as black bars. Data extracted from Wehr et al. (1993).’ 

Research with modern hunter gatherers suggests that Homo erectus would have spent periods of time asleep interspersed with waking and that they would not have one long uninterrupted sleep. This split sentinel duties.  Such bimodal sleep has been observed in many other animals and also in humans who live in pre-industrial societies lacking artificial light. In such societies, people go to sleep at dusk, wake for around an hour and then go back to sleep and rise at dawn.

Culture obviously has a big part to play – modern tribes such as the !Kung have a very fluid sleep state, sleeping when they feel like it, while other tribes sleep communally and many societies take naps in the afternoon.

Scientists still believe that the total number of hours amounted to 8 though – even if uninterrupted – and stress that this seems to be the ideal.

It is thought that a natural sleep pattern is bimodal during the long winter nights and gets compressed during summer.

In view of this,  we should not worry if our 8 hours is interrupted during the night and should not stress if we wake. We should  not turn blue lights on but relax until we resume sleep, using an eye mask and ear plugs to ensure we are able to make up the extra hours. We should adjust bedtime accordingly or take a nap in the afternoon if possible.




Give yourself a good amount of time to wind down before actually going to sleep – reading, relaxing, praying etc.

Limit blue light and increase red light in the hours before bed – switch to red/orange bulbs, install f.lux on monitors or better still turn them off, wear orange glasses if needed such as Gunnars or Uvex

Make sure there are no blue light emitting devices in the bedroom (alarm clocks etc.)

Create a pleasant sleep environment – ensure a good, supportive mattress, make sure that the room temperature is not too hot or cold, block out light with curtains or blinds, ensure the room is uncluttered and attractive

Use sleep aids if needed – eye mask, ear plugs

Ensure sufficient exercise in the daytime

Keep regular hours – try to go to bed and wake up at roughly the same time each day and keep a routine

Monitor your sleep with an App such as Sleep Time

Limit caffeine and alcohol

Read my blog post on sleep here and see the links below for further information.


Watch Dr Kirk Parsley’s excellent Tedtalk on Sleep below:


Russell Foster, University of Oxford, discusses circadian rhythms and mental health

The connection between sleep and mental health

Lighting to wake you up?

How artificial light is wrecking your sleep and what to do about it

The Sleep Council

The Great British Bedtime Report

Why do we sleep? Russell Foster

Read the Chapter ‘Honoring the Sun’ in Mark Sisson’s excellent book ‘The Primal Connection’

How much do we really know about sleep?

How much can an extra hour’s sleep change you?

Insufficient Sleep Is a Public Health Problem

See my notes from Dr Kirk Parsley’s excellent talk on sleep at Paleo f(x) here.


For a list of Paleo-friendly suppliers and products see the Resources and Suppliers page.

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