Mindset Article 24 – Sleep – Why do we need it?

Mindset Article 24 – Sleep – Why do we need it?

Adrian Leach

Senior Mindset Coach at Samuel and Co Trading. While studying and practising many energy healing systems spanning 40 years (EFT, TAT, TCM, Yuen Method, NLP, Applied Kinesiology, Qigong etc). He gained qualifications in Massage, Reflexology, Hypnotherapy and Psychotherapy. His goal is to continue to help his clients experience freedom from life’s emotional trauma, stress, negativity, limiting beliefs and to holistically balance the Mind, Body and Spirit.


Hi everyone, welcome back to my regular article. In this article, I want to cover the subject of sleep and why we sleep.

The simple answer to that question is, that we simply don’t know. Or more to the point, scientists and researchers don’t know why we sleep. I know why I sleep because I feel physically and mentally tired. So I get ready for bed, have a good nights sleep and wake up refreshed and full of energy. Well, that’s what we’re supposed to feel – right? We spend about 36% of our life sleeping, and if we live to a ripe old age of 90, we would have spent 32 of those years asleep – so it must be important. After all, it’s obvious why we need to eat and reproduce… but it’s not clear why we sleep at all.

There are many theories why we sleep but no one really knows what sleep actually does. From an evolutionary perspective, sleeping must really be important because when we sleep we’re vulnerable to being attacked by wild animals because our conscious mind shuts down and we stop moving. Although our conscious mind shuts down during sleep the brain is still highly active, in fact, some areas of the brain are more active during sleep then when we’re awake. Human beings are not alone when it comes to sleeping, it’s universal among mammals, birds, reptiles, amphibians and fish.

The brains master internal biological clock regulates our sleep-wake cycles, called our Circadian Rhythm, by releasing a hormone called melatonin during the hours of daylight and reducing melatonin production during darkness. Thanks to Edison and the invention of the light bulb, we now have light twenty-four hours a day and have messed with the natural sleep cycle of sleeping when it’s dark and waking when the sun comes up. On average, we need about eight hours of sleep, although some people seem to manage on less, while others need more.

Bats………………….. 20 hours
Lions…………………..13.5 hours
Laboratory rats……. 13 hours
Domestics cats…….12.5 hours
Baboons…………….. 9.5 hours
Humans………………. 8 hours
Pilot whales…………. 5.5 hours
Asian elephants……. 3 hours
Roe deer…………….. 3 hours
Giraffes……………….. 2 hours

Interestingly, dolphins and whales have the ability to shut down half their brain to allow sleep, while the other half remains active to allow them to surface and breathe. So let’s look at the cycle of sleep and see what the physical brain is doing before looking at the theories of why we sleep.

Sleep Cycles

The human brain has two sleep phases:

  • Rapid Eye Movement (REM sleep)
  • Non-Rapid Eye Movement (NREM sleep or Slow Wave Sleep)

Each stage of sleep has its own physiological, neurological and psychological features. They flow together to form whole sleep cycles. A complete cycle lasts around 90 to 110 minutes. So eight hours of sleep will give you around five sleep cycles per night.

Features of a normal sleep cycle:

Stage 1 NREM: Light Sleep – Brainwave frequencies decrease from Alpha waves (8-12 Hz) to Theta waves (3-8 Hz). You begin to lose muscle tone, causing twitches and jerks. You have hypnagogic hallucinations and lose self-awareness.

Stage 2 NREM: Light Sleep – Brainwaves show sleep spindles (spikes of electrical energy 12-16 Hz). You lose nearly all muscle tone as sleep paralysis takes over your physical body.

Stage 3 NREM: Slow Wave Sleep – Brainwaves decrease to Delta waves (0.5-3 Hz) – the lowest frequency marking a deep sleep. This is a dreamless stage where sleepwalking mostly occurs.

Stage 4 NREM: Slow Wave Sleep – Here, Delta waves are more pronounced as you enter a deep Slow Wave Sleep. It is the very deepest form of sleep.

REM Sleep – To complete the cycle, brainwave frequencies jump to highly active Beta waves (12-38 Hz). You have bursts of Rapid Eye Movement and muscle twitches. Most of your really vivid dreams happen during REM sleep.

Theories of Why We Sleep (and there are many theories).


Theory #1 – We Sleep To Rest

This theory is based on the fact that our lives are so hectic and fast-paced, that we physically burn up a lot of energy both mentally and physically. Therefore, we need to sleep in order to restore our mental and physical energy to recover and function normally. This theory is further supported by the fact that certain genes only switch on during sleep. Some of these genes are directly linked with mental health conditions such as schizophrenia and depression. https://www.bionews.org.uk/page_94284

Theory #2 – We Sleep To Heal

Sleep also allows our bodies to physically heal. This is marked by the constant growth and repair of the body’s immune and nervous systems, as well as our muscles and bones.

In a study on rats, sleep deprivation #2 actually slowed down the healing process of burns. Besides the immune system, sleep deprivation affects our metabolism (our internal chemical reactions). https://www.world-of-lucid-dreaming.com/sleep-deprivation.html

Theory #3 – We Sleep To Learn

Sleep is an active period in which a lot of important processing, restoration, and strengthening occurs that help us to solidify and integrate our memories. As we go through the day, our brain takes in an incredible amount of information. This information is first processed, filtered and stored; mainly while we sleep. During sleep, bits and pieces of information are transferred from our short-term conscious memory to stronger, long-term subconscious memory – a process called “consolidation”. Researchers have also shown that after people sleep, they tend to retain information and perform better on memory tasks.

Theory #4 – We Sleep To Dream

Everybody dreams, every night (even if you don’t remember them). Dreams are an expression of our unconscious thoughts and conscious experiences. They are so important that if we are seriously sleep-deprived, we actually start to dream while awake. Dreaming appears to be a by-product of REM sleep.

Theory #5 – Neuroplasticity (The Plastic Brain)

The phenomena of neuroplasticity, the brain’s ability to restructure and reorganise itself while we sleep is perhaps the most compelling and is a combination of all the theories mentioned. Sleep appears to play a crucial role in the brain development of infants and young children. Infants spend 13 to 14 hours per day sleeping, and about half that time is spent in REM sleep, where most dreams occur.

During the process of sleep, the process of “consolidation” strengthens existing neural networks while deconstructing unimportant ones, while the body restores and rejuvenates by repairing muscles and tissues, and synthesising hormones. The link between sleep, sleep deprivation and brain plasticity also affects adults and their ability to learn and perform a variety of tasks. It is also believed that the brain, during sleep, is able to clear out the waste produced through the process of “consolidation”.


How much sleep do we need?

Adults need 7-9 hours of sleep per night, one-year-olds need roughly 11 to 14 hours, school-age children between 9 and 11 hours, and teenagers between 8 and 10 hours. During these critical periods of growth and learning, younger people need a lot of sleep for optimal development through the process of “consolidation”. Sleep deprivation cannot be corrected by sleeping continuously to make up the lost time. The best sleep habits are consistent, healthy routines that allow all of us, regardless of our age, to meet our sleep needs every night.

Going without sleep

In a study by Turner et al, 40 people were allowed only 26 minutes of sleep per night. They were given cognitive tests which showed their working memory deteriorated by 38% over four days. Without REM sleep, they found it much harder to complete memory tasks and solve problems. Other sleep experiments have shown that procedural memory (your ability to perform certain skills) is dependent on REM sleep. Similarly, declarative memory (your knowledge of facts) relies on getting enough Slow Wave Sleep.

A 2014 study published in The Journal of Neuroscience found that a mere 24 hours of sleep deprivation caused healthy people to have hallucinations and other schizophrenia-like symptoms. Going without sleep will literally make you psychotic and, eventually, kill you. It’s clear that sleep is crucial to the body’s ability to function.



We all need nightly sleep to function normally. But there are plenty of things that get in the way of this: working night shifts, travelling through multiple time zones, sleep disorders like insomnia, stress, depression, the menopause etc. The body clock doesn’t shift to accommodate our lifestyle or the demands of working at night. It’s locked onto the same light-dark cycle. So when the night time shift-worker is going home to get some sleep, the body clock is saying ‘wake up’, this is the time to be awake. So when we’re tired through lack of sleep, we have poor memory, poor creativity, increased impulsiveness and poor judgement.


Despite this, we all go through it at some point or another. An increasing number of us are chronically sleep-deprived because of our modern lifestyles. And the cost of that sleep deprivation on society is thought to be massive. American businesses are thought to lose $100 billion in productivity each year. Even worse, tired workers are thought to be responsible for disastrous assaults on nature – ranging from the giant oil spillage of the Exxon Valdez to the nuclear meltdowns of Three Mile Island and Chernobyl. https://www.world-of-lucid-dreaming.com/sleep-deprivation.html

So, when our brain is tired it starts craving things to wake it up; drugs, stimulants and caffeine is the preferred stimulant across much of the Western World. Most of the day is fuelled by caffeine or nicotine and when it gets to 11:00 o’clock at night, the brain says to itself ‘I need to be asleep shortly’, ‘what are we going to do about that while I’m feeling completely wired?’ Well, some resort to alcohol. Now, small amounts of alcohol are effective to help sedate you, to help ease the sleep transition. Alcohol doesn’t provide sleep, it sedates you, and so harms some of those neural processes going on during memory consolidation and recall, so don’t become addicted to alcohol as a way of getting to sleep at night.

Another connection between loss of sleep is weight gain. If you sleep around 5 hours per night or less, then you have a 50% likelihood of being obese. The connection here is sleep loss seems to give rise to the release of the hormone ghrelin, the ‘hunger hormone’. A signal gets sent to the brain that ‘I need carbohydrates’ and particularly sugars. So, there is a link there between tiredness and a predisposition to weight gain. Tired people are massively stressed, which causes a lack of memory. Short term stress or ‘acute stress’ is okay but, sustained stress associated with sleep loss is a problem and leads to suppressed immunity. Tired people tend to have a higher rate of infection. Higher levels of stress release glucose into the system and eventually, you become glucose intolerant, leading to Diabetes 2. Stress increases cardiovascular disease as a result of raising blood pressure.

How do you know if you’re getting enough sleep?

If you need an alarm to get you out of the bed in the morning, if you’re taking a long time to get up, if you need lots of stimulants, if you’re grumpy or irritable or if you’re told by your work colleagues that you’re looking tired and irritable then chances are sleep deprived. So what can you do to help get a better nights sleep? The first thing to do is to prepare your bedroom for sleep. Make your bedroom as dark as possible and make it slightly cooler than the rest of the house. Reduce the amount of light exposure you’re exposed to at least 30 minutes before going to bed. Light exposure increases your level of alertness. Turn off the mobile phones and computers, anything that’s going to stimulate and excite the brain. Try not to drink caffeine too late in the day, ideally not after lunch. Start to slow down prior to going to bed in preparation for sleep. However, in the morning seek out light as this will stimulate the biological clock.

Final Thoughts

The functions of sleep are still unfolding. We understand the natural sleep cycles and a number of effects of sleep on the brain and body. However, there is no unifying theory that answers the question “why do we sleep?” Take sleep seriously, as a good nights sleep;


  • Concentration
  • Attention
  • Decision making
  • Creativity
  • Social skills
  • Health


  • Mood change
  • Stress
  • Anger
  • Impulsive behaviour
  • Smoking and drinking

Hopefully, you are still awake and found this article different and insightful. As always, I hope you have enjoyed the input. I look forward to seeing any discussions and interaction from the community.

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