How Does Sleep Impact Your Health & Fitness? • Common Purpose

Featured read

How Does Sleep Impact Your Health & Fitness?


Words by Common Purpose Team

Published 7th November 2019

Approximately 7 Minutes Reading Time

Brief Article Overview

  • Despite the lack of knowledge regarding the origin and reason for sleep. There is no doubt that regular sleep is vital for health and is a consistent theme throughout life on earth.
  • Sleep plays an integral role in the recovery, restoration and development of all systems within the human body.
  • Sleep quality and quantity are on the decline in the UK.
  • Raising awareness of its importance may change attitudes towards sleep and may improve human health on multiple levels.

Introduction – A Core Function in Life

Oxygen, food, water and sleep; the basic fundamentals for life as we know it. But have you ever stopped to ask yourself, why do we sleep? Doesn’t it seem like a strange phenomenon? Having to subject ourselves to such a vulnerable state of unconsciousness seems to fly in the face of evolution. Imagine our ancient ancestors, constantly in a state of anxiety, simultaneously hunting for the next meal and on the run from predators. On the face of it, it would seem that it’s really impractical to go unconscious for 8 hours every night.

This hasn’t gone unnoticed amongst evolutionary and sleep scientists, and according to the Author of Why We Sleep, The New Science of Sleep and Dreams Matthew Walker;

“The cost of losing consciousness to survival is astronomical.” 

Clearly, the importance of sleep must then supersede the potential dangers it invites. Sleeping is universal and can be reliably observed amongst every single animal on this planet, no matter the environmental climate and pressures on survival.

The long-held theory that sleep is simply a state of inactivity just doesn’t seem to make sense. In fact, the latest scientific research reveals just how active the brain is when we sleep and how much we suffer when sleep is deprived, even temporarily. This core function in life is a non-negotiable staple. There is even a theory that life itself started in a state of ‘sleep’ and partial to full consciousness was developed further down the evolutionary timeline. 

Why Do We Sleep?

The answer is multifactorial and remains largely a mystery. Philosophers such as Sigmund Freud and Carl Jung, for example, have all taken the phenomena of dreams in particular quite seriously, and as philosophers do, have ended up with more questions than answers. 

Since the 1960s, thanks to the advancements in technology and the development of neuroscience, we can begin to put some theories to the test and scratch the surface of this deep and complex subject. 

A detailed review of the latest in sleep science isn’t within the scope of this article, but here is an overview of the crucial role sleep plays in our health and wellbeing:

  1. Global Cognitive Function – During sleep, new neural pathways are created which have been shown to improve cognitive abilities such as memory, emotional stability, learning, decision making and reaction times. (1, 2 & 3). 
  2. Preventing Neural Degeneration – Sleep has a profound impact on the risk of disorders such as Dementia and Alzheimers. (4)
  3. Clearing, Repairing and Renewing – Sleep initiates the activation of specific genes which code for the regeneration of old or damaged cells. (5)
  4. Hormone Regulation – The circadian rhythm is tightly coupled with hormone production and inhibition, which affect insulin resistance, mood, reproductive health, appetite, and metabolism. (6)
  5. Immune System Function – Fighting sickness and reducing the risk of disease/illness. It has been demonstrated that a lack of sleep significantly reduces the amount of NKCs (natural killer cells), which protect your body from pathogens. (7)

How Much Sleep Do We Need?

The general consensus for sleep recommendations is no less than 7 hours per night for an adult. It’s useful to note that sleep requirements do change throughout life. Check out this graph, which outlines the most up to date recommendations on sleep divided amongst specific age groups:

As you can see there are minimum, optimum and maximum ranges for each age group. Although there are conditions in which sleeping for too long can be unhealthy, this is quite a rare occurrence and is a topic for another time.

What this chart seems to indicate is that the ages at which the highest rate of development is occurring i.e. growth and learning, require the most amounts of sleep. It’s logical therefore to assume that if you want to develop and learn effectively as an adult, sleep is not only helpful but a key player in this regard.

The UK’s Current Sleep Health

According to the Great British Bedtime Report, this is the average amount of Sleep Brits get per night;

  • 70% of Brits get less than the recommended 7h of sleep! 
  • Almost half (47%) of Brits blame poor sleep on stress and worry, other causes include partner disturbance and environmental factors (light and noise).
  • The average Brit goes to bed at 11.15pm and gets just 6h 35mins of sleep per night!

Sleep in Modern Life

The above statistics clearly show that there is a disparity between our modern lifestyles and meeting sleep recommendations. 

It’s completely normal, for example, to finish work at 6/7pm, socialise with friends or family or sit in front of a screen to wind down, have a shower and before you know it, it’s midnight and you’re setting your alarm for 7am the next day. 

This only gives you a 7-hour window of opportunity for sleep. If you don’t have a solid sleep strategy in place, find it difficult to get to sleep, or your sleep is often disturbed, it’s highly unlikely you’ll squeeze in more than six hours of high-quality sleep (especially if you add alcohol, caffeine, artificial light and noise into the mix, more on that in part 2). 

Sleep loss due to voluntary bedtime curtailment has become a hallmark of modern society…  Chronic sleep loss, [whether] behavioral or sleep disorder related, may represent a novel risk factor for a plethora of disorders, illnesses and diseases”

– Spiegel K.

The Weekend Payback

Do you think you can pay back the sleep debt you’ve accrued over the week with a Saturday lay in and lazy Sunday? First of all, if you have kids or any kind of active social life, good luck with that. 

Secondly, let’s do some simple math; if you owe 2 hours per night over 5 nights, that’s an extra 10 hours you have to make up over two days? So you’re going to have to sleep 13 hours on both Friday and Saturday night. It’s pretty difficult to get this amount of high-quality sleep in one go. 

Additionally, according to recent studies, negative consequences of partial sleep deprivation occur almost immediately. A bit like interest on a credit card. Sleep debt doesn’t remain constant. It builds compound interest over time with the negative effects exponentially increasing!

Is it Time For Change in Perspective?

We feel that a full night of quality sleep is too often seen as a dispensable commodity. Here are some questions we would like you to ponder over the next few days to perhaps change this perspective and initiate some self-reflective mindfulness when it comes to your own sleeping patterns.

  1. How highly do you prioritise sleep? 
  2. How many hours of quality sleep do you average per night?
  3. Have you ever consciously noticed your sleep habits and routines?
  4. How much time do you normally give yourself as a window of opportunity to sleep?
  5. How do you feel when you wake up?
  6. Do you need caffeine to feel awake in the morning?
  7. When was the last time you had a great night’s sleep?

We hope this article has given you a helpful perspective on sleep. It’s clear that more than 7 hours of sleep a night is a non-negotiable staple of health and is not a dispensable commodity. 

In Sleep (part 2), we will be discussing what a good night sleep looks like and how to clean up your sleep hygiene. 

If you’re interested in starting your health and fitness journey with us…

Disclosure: This article is not to be used as medical advice. If you are currently experiencing physical or mental health issues, please seek professional advice from a fully qualified Nutritionist, GP or Physiotherapist. 



  1. Sleep deprivation: Impact on cognitive performance. Alhola, P., & Polo-Kantola, P. (2007). Neuropsychiatric disease and treatment. 3(5), 553–567.
  2. “A deficit in the ability to form new human memories without sleep.” Yoo, S., Hu, P. T., Gujar, N., Jolesz, F. A., & Walker, M. P. (2007). Nature Neuroscience 10(3): 385-392
  3. Neural basis of alertness and cognitive performance impairments during sleepiness. Effects of 24 h of sleep deprivation on waking human regional brain activity. Thomas M, Sing H, Belenky G, Holcomb H, Mayberg H, Dannals R, Wagner H, Thorne D, Popp K, Rowland L, Welsh A, Balwinski S, Redmond D. (2000) J Sleep Res. Dec;9(4):335-52 
  4. Sleep, Cognitive impairment, and Alzheimer’s disease: A Systematic Review and Meta-Analysis. Omonigho M. Bubu, MD, MPH,  Michael Brannick, PhD, James Mortimer, PhD,  Ogie Umasabor-Bubu, MD MPH, Yuri V. Sebastião, MPH,  Yi Wen, MS, Skai Schwartz, PhD, Amy R. Borenstein, PhD,  Yougui Wu, PhD, David Morgan, PhD. (2017) Sleep, Volume 40, Issue 1.
  5. Mistimed sleep disrupts circadian regulation of the human transcriptome. N. Archer, E. E. Laing, C. S. Möller-Levet, D. R. van der Veen, G. Bucca, A. S. Lazar, N. Santhi, A. Slak, R. Kabiljo, M. von Schantz, C. P. Smith, D.-J. Dijk Proc. Natl. (2014) Acad. Sci. USA (2014) 111(6)
  6. Role of sleep and sleep loss in hormonal release and metabolism. Leproult, R., & Van Cauter, E. (2010). Endocrine development, 17, 11–21
  7. “Partial sleep deprivation reduces natural killer cell activity in humans.” Irwin, M. et al. (1994). Psychosomatic Medicine 56(6): 493-498.)