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7 hours of sleep or 8 hours of sleep? What does the sleep research say?

Ideal Amount Of Sleep
This post was last updated on March 12th, 2021 at 10:30 am
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Getting the ideal amount of sleep for health is just as important as eating healthy foods and getting enough exercise.

  • According to new studies, people who sleep less than 8 hours a night are more likely to suffer from depression and anxiety.
  • Looking at the results of a collection of previous sleep studies can we deduct from these the ideal amount of sleep in terms of optimal health?
  • Nonetheless sleep needs do vary from person to person. What is the best way in finding out if you are getting the right amount of sleep?

What are the benefits of sleep?

Sleep is fundamental to good health. It is not just a rest time. It is a time when the body builds up itself. During sleep, the body works hard to rebuild the muscles that have been broken down in the course of the day’s activities. Harmful plaques and waste produced by the brain are also eliminated during sleep. These are essential properties that keep the body and mind functioning at optimal levels.

During sleep, consolidation of memory takes place. What does this mean? The implication is that during sleep, the mind processes and responds to important experiences and emotions of the day, and commits them to memory.

Sleep also helps in regulating the emotions. To be frank, if you are deprived of a night’s sleep, your emotional response to negative feelings can increase by 60 percent. Also, a lack of it makes it difficult for your body to regulate appetite control, optimize the immune system, enhance metabolic function and also help regulate body weight.

Finally, sleep is essential in regulating the internal clock or circadian rhythm. The circadian rhythm runs on a 24-hour timeline. It regulates sleep and wake time. It also helps in regulation of immune function, inflammation and metabolism.
Depriving yourself of sleep or sleeping at odd times of the day or in bright light may distort the circadian rhythm and all the processes regulated by it.

While you may think you’re resting well, you should note that not all sleep is created equal. Not only is it important to sleep long each night, the sleep should also be of good quality. That notwithstanding, there is no universal definition for sleep quality. Nevertheless, it may be defined as the duration of time it takes you to fall asleep, how often you wake up each night, how rested you feel the next day or how much time you spend in different stages of sleep. Because sleep plays a role in the maintenance of good health, it is best that you make it a priority to sleep well each night.

How much sleep that you need depends on several factors. Every individual has his own unique needs and preferences, and the same applies to sleep time and sleep quality. However, the amount of sleep a person needs each night is determined mainly by age.

Official recommendations for sleep duration are classified by age group:
• Older adults (65+): 7-8 hours
• Adults (18-64 years): 7-9 hours
• Teenagers (14-17 years): 8-10 hours
• School children (6-13 years): 9-11 hours
• Preschoolers (3-5 years): 10-13 hours
• Toddlers (1-2 years): 11-14 hours
• Infants (4-11 months): 12-15 hours
• Newborns (0-3 months): 14-17 hours.

The ideal amount of sleep for people may also vary depending on a variety of factors such as genetic makeup. Some mutations in your genes can affect how much sleep you get, the time of day you love sleeping and your response to sleep deprivation.
For instance, those with a specific mutation can manage a 6-hour sleep and still get by fine, whereas those without need would require an average of 8 hours. The unfortunate thing is genetic makeup cannot be changed, and there’s no practical way to know if you have any of these mutations.

What does the sleep research say?

1. Sleep and relaxed, positive thinking – 8 hours

Study indicated that sleeping shorter than 8 hours associated with:
• Intrusive negative thinking tendancies.
• Difficulty to shift focus away from the negative information
• More likely to suffer from depression & anxiety

“Shorter sleep duration and longer sleep onset latency are related to difficulty disengaging attention from negative emotional images in individuals with elevated transdiagnostic repetitive negative thinking”

2. Sleep and longevity – 7-8 hours

The normal sleep time needed by an average adult is around 7-8 hours. Researchers in the UK and Italy analyzed data from 16 separate studies spanning a period of 25 years, with more than 1.3 million participants and 100,000 deaths. Findings were published in the journal Sleep. Those who had a sleep time lesser than six hours each night had a higher chance of dying prematurely. People who slept longer than 8-9 hours had a much higher chance than the former group.
Researchers also found that people whose sleep time was reduced to five hours or less had 1.7 times the risk of death from all causes.

3. Sleep and managing the appetite – 6.5 TO 7.4 hours of sleep optimal not to go above 8.5

Your body’s energy needs can be increased by poor sleep habits. At night, your calorie needs and movement are drastically reduced. However, when you deprive yourself of sleep, your brain will release the hunger hormones. This can cause binge eating, less exercise and of course, weight gain and obesity.
A study conducted by Japanese researchers, featuring 5000 Japanese adults with diabetes type 2 found that those who had a daily sleep of less than 4.5 hours or more than 8.5 hours had a greater BMI and A1C values. The A1C values is a measurement of a person’s blood sugar levels in the course of three months. The lowest A1C levels recorded were found in participants who had a night sleep of 6.5-7.4 hours daily.
Deprivation of sleep also affects children. A studycarried out in 2014 showed that children who had lesser sleep time had an increased risk of obesity and a higher body mass index. These could prove detrimental to children during their growing years.

4. Sleep and the immune system – over 5 hours

Cytokines are released by the body during sleep. These compounds have a protective effect on the immune system by combating infections and inflammation. When one is deprived of sleep, you may not have enough cytokines to keep you from getting sick.
A research study conducted in 2013 found that depriving oneself of sleep raised the amount of inflammatory compounds in a person’s body. These compounds are associated with allergies and asthma.
The researchers studied people with long-term sleep deprivation and limited sleep deprivation of at least four to five hours a night for a week. It was discovered that the participant’s immune system were compromised by lack of sleep.

5. Sleep and weight-management – Over 7 hours

Poor sleep is linked to excessive weight gain. Studies have shown that people who sleep for shorter durations tend to weigh more than those who get adequate sleep.
In one massive review study, it was discovered that children and adults who slept less were more likely to obese by 85% and 95% respectively. It is believed that so many factors mediates the effect of sleep on weight gain. Some of these factors include motivation to exercise and hormones.

6. Sleep and brain function – 7-8 hours

Sleep helps in optimal brain function. All parts of brain function are improved upon when one gets adequate sleep (7-8 hours). This includes productivity, performance, concentration and cognition. Sleep deprivation impacts negatively on this. Two studies prove this:
In the first study, interns on a “traditional schedule” made serious medical errors increasing by about 36 percent more than interns on a schedule that allowed more sleep.
Another study found that sleeping for shorter periods can impact negatively on some aspects of brain function to a degree similar to that cause by alcohol intoxication.

7. Sleep and maximizing for athletic performance – 6-7.5 hours

Studies have shown that sleep enhances athletic performance. A study conducted on basketball players showed that sleeping for longer periods was linked to significant improvement in speed, reaction times, mental wellbeing and accuracy.
Less sleep has also been associated with poor performance in exercises and functional limitation in women of older age.
A study featuring 2,800 female participants found that poor sleep was related to slower walking, greater difficulty in carrying out independent tasks and lower grip strength.

8. Sleep and effective glucose metabolism – 8 hours

Restriction of sleep reduces insulin sensitivity and affects blood sugar. This has been experimentally verified.
In a study of healthy young men who restricted sleep time to no more than 4 hours per night for 6 nights in a row, there were noticeable symptoms of pre-diabetes. This was resolved after the participants increased their sleep time for a week.
Poor sleep time is also linked to negative effects on blood sugar levels in the general population.

On analysis of all of above we can deduct that results are slightly conflicting.

What is the best way in finding out if you are getting the right amount of sleep?

Doctor Rangan Chatterjee talks about how to get an immediate snapshot of your sleep health in his new book The 4 Pillar Plan: How to Relax, Eat, Move and Sleep Your Way to a Longer, Healthier Life He uses a rating system to discover how patients rate their sleep. The rating system focuses simply on 3 questions and on allocating yourself 2 points for every question that you answer “Yes” to:

    Do you wake up feeling refreshed?
    Do you wake up at the same time without using an alarm clock (give or take 30 minutes)?
    Do you fall asleep within 30 minutes?

If the answer to all 3 questions is a “Yes”, then quite simply, you have a good overall quality of sleep health.



General health freak extraordinaire obsessed with health research and optimal health performance. Note, I have other loves in my life, these include travel, good coffee, red wine, films & yoga.

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