One of my favourite lines in Dr Matthew Walker’s international best selling book Why We Sleep is this “I was once fond of saying, sleep is the third pillar of good health, alongside diet and exercise. I have now changed my tune. Sleep is more than a pillar; it is the foundation on which the other two health bastions sit.”

Reading these words on a page (and of course being me, going in depth and researching this further) changed me in some ways. As a registered nutritional therapist, it’s easy for me to get sucked into promoting healthy, manageable diet and lifestyle recommendations to aid health problems. It has been drilled into me to look at an individual’s symptoms and get to the root cause to help eradicate that problem thus leaving the body able to help heal itself through the two pillars mentioned above (and obviously with simultaneous medical supervision from my clients general practitioner). Sleep has always been an important topic amongst this recipe to health, but I never knew just how important or placed emphasis on promoting it until I delved deeper in and saw what a difference it made to my clients goals. 

Whether you want to tackle cardiovascular disease, shed a few pounds, enhance fertility, regulate hormones, help digestive complaints, improve cognition or fight deadly diseases, without sufficient sleep, you will be fighting the hardest battle to get there. In fact every major system, tissue and organ in our bodies suffer when sleep becomes short. 

More than 20 large scale scientific studies have tracked millions of individuals over decades showing the same clear relationship, the shorter your sleep, the shorter your life. Below I have outlined just some of the ways disrupted or insufficient sleep can impact our health and wellbeing. 

Our Cardiovascular System

The results of almost 2 decades of studies on over 500,000 individuals of different genders, ages and races across the world has shown that short sleep was associated with a 45% greater risk of fatal and nonfatal coronary heart disease within a 7 to 25 year window. (1) In many of these studies the link between the two remains strong even after accounting for other known cardiac risk factors such as smoking, physical activity and body mass. Adults over 45 who get 6 hours or less sleep per night are 200% more likely to have a heart attack or stroke in their lifetime. A large part of the reason why the heart suffers so much under the weight of sleep deprivation is the blood pressure. Sleep loss pumps up blood pressure across your entire body which can lead to cardiac failure, ischemic heart disease, stroke or kidney failure. 

A lack of sleep not only increases your heart rate and pumps up blood pressure. It also erodes blood vessels and causes them to become narrow or completely blocked, especially our coronary arteries (responsible for supplying the heart itself). 


The less sleep we get, the more likely we are to consume higher calorie meals, in addition to that, our bodies become less able to manage these calories effectively, especially when it comes to balancing out blood sugars. It  is due to this poor management of sugar regulation and higher consumption of calorie intake when sleep deprived that can contribute to becoming overweight, obese and increase our chances of developing type 2 diabetes. 

In healthy individuals, the hormone insulin will trigger the cells to absorb glucose from the bloodstream to be used as an energy source, however if these cells stop listening or responding to insulin (for example due to a continuous supply for overfeeding) they cannot effectively absorb the glucose circulating through the bloodstream, and just like a blocked drain, these levels will cause a swell which will cause the body to go into a hyperglycemic state, eventually leading to the individual becoming pre-diabetic before ultimately developing type 2 diabetes. 

The same principle applies to loss of sleep and weight gain. Two hormones that control our appetite (Leptin and Ghrelin) start to misbehave when sleep deprived. Leptin’s role is to signal the feeling of fullness whereas Ghrelin triggers a sensation of hunger. Studies have shown that sleeping 5 to 6 hours a night triggers disruption to these hormones (decreasing concentrations of Leptin and increasing the levels of hunger-stimulating Ghrelin), leading to weight gain. 

Reproductive System 

Sleeping less than 7 hours a night has been shown to reduce a mans testosterone level so much that it can effectively age him by 10 to 15 years in terms of testosterone vitality. The same can be said for sperm count, with studies showing men who experience less sleep or report poor quality sleep have 29% lower sperm count than those who obtain restful nights sleep, with the sperm themselves having more deformities.

As with men, women who sleep 6 hours or less a night experience a 20% drop in follicular-releasing hormone, which peaks just before ovulation and is necessary for conception. Women who are pregnant and routinely get less than eight hours of sleep per night are also at higher risks for miscarriage in the first trimester. 

Sleep and the Immune System 

Oh that age old saying to rest when you’re unwell. In fact when we are unwell (think of those yucky snotty noses, sore throat, coughs and total lack of energy) our bodies make us feel sleepy so it can get on with fighting against infection. 

It does this by deploying all of its secret agents (think natural killer cells), a reduction in sleep, even for just one night can hinder our bodies immune system and here is where the issue of cancer becomes relevant. In fact, sleep is so important for our immune system that the world health organisation has classified shift working as a carcinogen. Our natural killer cells have a roll in finding and successfully killing malignant tumour cells, so what we want is an abundant army of these guys ready to fight, but you get the complete opposite with a lack of sleep. 

The link between lack of sleep and cancer can be mostly attributed to the agitation of the sympathetic nervous system when there is a lack of sleep. Our nervous system ramps into overdrive which provokes an unnecessary and sustained inflammation response from the immune system. It’s this prolonged chronic inflammatory response that a lack of sleep provokes that causes a whole host of health problems, including those relevant to cancer. 

Sleep loss and our DNA

Not only can sleep loss increase your risk of developing Alzheimer’s disease, diabetes, mental health disorders, obesity, hypertension, cardiovascular disease, cancers, reproductive disorders and autoimmunity, it can also fragment your DNA. 

Thousands of our genes rely on consistent and sufficient sleep to stay stable. A lack of sleep will cause these genes to malfunction and not translate their codes efficiently if at all, causing all sorts of problems to our health and well being. In fact a study into sleep loss and DNA damage showed that around 711 genes had been abnormally revved up in their expression by a lack of sleep with the rest shutting down completely. Scarily, the genes that had shut down were those genes responsible for maintaining metabolism and optimal immune responses and those regulating cholesterol. 


1. 0.Tochikubo, A. Ikeda, E. Miyajima, and M. Ishii, Effects of insufficient sleep on blood pressure monitored by a new multibiomedical recorder, Hypertension 27, no. 6 (1996).

2. M. Walker, 2018. Why We Sleep. Harlow, England: Penguin Books. Penguin Books

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