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Why We Need Eight Hours Of Sleep
January 30, 2018 donecountingsheep

Why We Need Eight Hours Of Sleep

Posted in Sleep Better
8 hours of sleep is ideal

(PS.  A Good Night’s Sleep Is When You Wake Refreshed)


When It Comes To Hours of Sleep Needed A Night Eight Is The Magic Number

Sleep is viewed by some as a colossal waste of time, often accompanied by a “there will be plenty of time to sleep when I’m dead” attitude. Unfortunately for those who think like that, the scientific evidence is such that, if you don’t prioritise your sleep you may get there quicker than you had hoped.  So how much is enough sleep?  How many hours of sleep a night do we actually need? Here’s where you will find some of the answers.

Sleep Requirements For Different Age Groups

The National Sleep Foundation conducted a study of 18 multi-disciplinary experts who reviewed over 300 research articles in order to determine the most scientific assessment for sleep requirements amongst different age groups, taking into consideration over-all health, cognitive, physical and emotional health.

Hours Of Sleep Required By Age

These are the results of the study and the hours of sleep required for each age:

  • Newborn  14 – 17 hoursInfants  12 -15 hours
  • Toddlers  11 – 14 hours
  • Preschoolers  10 – 13 hours
  • School aged children  9 – 11 hours
  • Teenagers  8-10 hours
  • Young adults and adults  7 – 9 hours
  • Older adults  7 – 8 hours

The Numbers Are Important (To A Point)

And in 2010 researchers conducted a review of 16 separate studies carried out over 25 years which covered over 1.3 million people and more than 100,00 deaths. Their findings, published in the Journal of Sleep, concluded that those who routinely slept for less than six hours per night have a 12% greater risk of dying prematurely than those who mainly slept for seven to eight hours per night. The same study also showed that there was an even greater risk for those who routinely got more than nine hours of sleep per night. There does seem to be a narrow margin for the right amount of sleep and the health benefits of that.

Eat For Eight (Hours of Sleep)

The number eight here is interesting for another reason.  It ties in with our own belief at Done Counting Sheep that, for the majority of insomniacs, it is our metabolism (the chemical processes that occur within a living organism in order to maintain life) that is one of the main causes of insomnia.  A healthy person, with a good diet and a healthy thyroid etc., can store upward of eight hours of glycogen (the body’s store of sugar which provides the energy needs throughout the night) in their liver. A lack of this store can lead to sleeplessness because as the sugar supply dwindles from the liver, this is detected in the blood and the body maintains blood sugar by releasing adrenaline which scavenges for energy from elsewhere. But the unfortunate side effect of adrenaline is mental alertness, which of course you don’t want at night.

Eight Important Reasons To Get Those Eight Hours Of Sleep

1.  Get your Beauty Sleep for Youthful Skin

There is a whole area of medicine concerned about the effects of psychological stressors on skin and it is called psychodermatology. Insomnia is considered to be one of these stressors.

Collagen is the protein within our skin that gives us a youthful appearance because it supports structure and elasticity and through this, reduces wrinkles. Sleep debt directly interferes with the processes of the skin’s collagen formation by raising cortisol levels and blocking the role of the immune system in collagen repair.

Stockholm University published a study in Royal Society Open Science Journal, which showed that after just two nights of poor sleep, the difference in the skin is perceived by strangers describing the unfortunate volunteers as ‘less attractive’.

2.  Memory and Concentration

Sleep deprivation is a common cause of memory loss. It has long been established that sleep plays a vital role in memory consolidation. During the REM (rapid eye movement phase of sleep) the day’s events are consolidated and fixed as memories.

In 2017 scientists at Western University in Ontario compared the brain activity of participants when they had slept well and when they had a reduced amount of sleep. They were then challenged with several brain-teasing games whilst being given an MRI scan of the brain. Much less activity was observed in the brain after the participant had been deprived of sleep, explaining the marked decline in cognitive performance that many people feel due to lack of sleep.

3.  Detoxification of the Brain and Mental Health

It was discovered in 2013 that during sleep, the space between the brain cells enlarges by 60%, allowing a fast and efficient exchange of cerebrospinal fluid and detoxification of neuronal waste products. This has major implications for mental health disorders and may shed light on why insomnia increases the risk for Alzheimer’s Disease.

4.  Cancer and Immunity

The World Health Organisation has recently classified the sleep-disruptive effects of shift work as a “probable Carcinogen” and it has been known for some time that shift work is associated with a higher risk of breast cancer.

Dr Michael Irwin of the University of California identified a very rapid and direct effect of lack of sleep on the immune system.  Just a single night of four hours sleep reduced the number of natural killer cells circulating in the immune system by 70%. Natural killer cells are white blood cells that play a vital role in protection against cancer and viruses.

5.  Weight Gain

Not getting enough sleep reduces our sensitivity to insulin, raises cortisol levels and increases ghrelin (a hormone which increases hunger). Altogether, creating the perfect storm for weight gain.

6.  Heart Health

Matthew Walker, neuroscientist and author of “Why We Sleep”, described in his book the relationship between heart health and sleep. Getting six hours of sleep or less per night increases the risk of fatal heart attack or stroke by 200%. And, interestingly, every year in spring, when the clocks go forward, medical records show that heart attacks go up by 24%!

7.  Relationships

Poor sleepers are twice as likely to have relationship problems, according to the Great British Sleep Survey. This is likely due to the low mood, irritability and fatigue which can result from not getting enough sleep.

8.  Fertility

Men who only sleep for five to six hours per night have testosterone levels of a man ten years older. Men are increasingly being diagnosed with low sperm count and lack of sleep may be a significant contributing factor to the rise in infertility among men.

A recent study has suggested that women with insomnia are three times more likely to suffer from infertility problems than their counterparts who sleep well. Dr Wang of the Tri-Service General Hospital and National Defense Medical Center in Taipei, Taiwan and author of the study told Reuters News, “Women of child-bearing age should sleep earlier, avoid night shift work or cellphone use before sleep. Moreover, a healthy diet, regular exercise and a good lifestyle are important to prevent infertility.”

There is such a strong case for sleeping well to strengthen, support and protect every area of our well being. Are you getting your eight hours?  If not, you can make a start by following our Ten Tops Tips For Better Sleep.


Did you find this useful?  Join us on Facebook for more helpful advice and tips on how to sleep well.

Photo by Tristan Colangelo on Unsplash




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