Normal sleep: What Africans should know

Sleep_promo image depicting red bedroom table clock and Zs




Sleep facts


  • Sleep is a complex biological process typified by distinct cycling of brain waves in intervals of about 90 minutes duration. The cycling is associated with slowing or suspension of different body functions like breathing, heart rate and muscle activity.


  • Five stages of sleep are described; N1, N2, N3/N4 (so called slow wave sleep, or SWS) and REM.


  • These stages fall variably within two broad types of sleep; i.e. Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) sleep.


  • NREM sleep occurs first and is longer during earlier period of sleep, while REM sleep occurs later and is longer during the later phase of sleep. Dreams and nightmares occur more and are more dramatic during REM sleep.


  • While we do not yet know for certain why we sleep, scientists have proposed that the benefits of sleep include cleansing of the brain of waste products; rest, restoration and rejuvenation of the body; conservation of energy and improvement of body immunity to stave off infections.


  • Several environmental, biological, psychological and social factors influence the duration and quality of sleep.


  • There is no ideal sleep duration per day that applies to everyone. While 8 hours is regarded as average for most adults, more detailed recommendation are available for sleep duration across different age groups.


  • Proper sleep hygiene helps to ensure sleep regularity, quality and the promotion of sleep health.


  • Chronic lack of sleep can have serious consequences including lack of concentration, poor decision making, reduced motor skills, irritability, depression and more.


  • Two broad groups of sleep disorders with distinct features have been described. They include Dyssomnia and Parasomnia.


  • Dyssomnia is a sleep disorder typified by inability to fall and stay asleep. Examples include Insomnia (difficulty falling and staying asleep), Hypersomnia (excessive daytime sleepiness), Narcolepsy (sudden daytime attacks of deep sleep with or without drop attacks), Restless limb disorder, Obstructive sleep apnea, etc.


  • Whereas, Parasomnia is a sleep disorder that is typified by abnormal behaviour and/or the “zombie-like” engagement in motor activity during sleep. Examples include Sleep walking, Sleep talking, Sleep terror, Nightmares, etc.







According to a recent literature review from Nigeria, basic knowledge about the scientific basis of sleep is low across communities in African countries.


So is the availability of healthcare providers with special training in sleep medicine and the availability of institutions and technical services dedicated to the care of sleep disorders.


Sleep is a universal and fundamental necessity for good population health irrespective of race, gender and nationality. However, different local factors, most especially socioeconomic status, may impact sleep quality and by extension the prevalence of sleep disorders between and within nation states.


Compared to other high income nations of the world, very few studies are available about the prevalence of sleep disorders across African countries and diverse cultural misinformation abound about the nature and purpose of sleep within the region.


The few available reports from Nigeria, South Africa and Ethiopia point to a wide range of 69%, 9.1% and 71.3% respectively in the prevalence of sleep disorders in different population study groups.


This indicates that sleep disorders is a serious population health issue in sub-Sahara Africa and more refined studies are needed to help shape public policy to address it.


The purpose of this general article is to provide the reader especially from Africa with credible and basic information about the science of sleep, hoping that it will assist in gaining insight into the importance of sleep and sleep health.


Topics that will be covered here include:

  • What is sleep?
  • What are the different types and stages of sleep?
  • Why do you need to sleep?
  • What are the ideal and recommended durations for a good sleep?
  • What are the influencers of the duration and quality of sleep?
  • What are the effects of poor sleep?
  • Tips on how to sleep better?


Other aspects of sleep, like sleep aids, causes and types of sleep disorders, diagnposis and management, etc., will be covered in separate reports.



What is sleep?


Sleep is a complex but fascinating biological process that is still not fully understood.


Quality sleep is essential for physical, mental and psychological well-being.


Learning, memory processing, cellular repair, growth and brain development are among the most important functions of sleep.


Although the average adult spends approximately a third of the day sleeping, we still do not fully understand why people sleep.


In the past, sleep was thought to be a state in which the “body stops functioning, shuts down and takes a break.”


The truth is, we now know differently.


When you observe a sleeping person, s/he may appear inactive. But numerous sleep studies conducted in humans have confirmed that some body and brain functions are actually active during sleep than in the awake state.


So, what would be an appropriate definition of sleep?


Sleep can be defined as a temporary inactive state of the mind and body that is marked by altered alertness and awareness, reduced muscle movement and reduced interaction with the environment, while the brain is rejuvenating and memory is being strengthened.


Different brain waves have been identified and associated with different types and stages of sleep.




What are the different types and stages of sleep?


Two broad types of sleep are recognized:

  1. Non-Rapid Eye Movement Sleep (NREM)
  2. Rapid Eye Movement Sleep (REM)


Non-REM sleep occurs first and it transitions into what is called slow wave sleep or deep sleep. During this phase, body temperature and heart rate fall, and the brain uses less energy. People spend more period in Non-REM sleep.


REM sleep, also known as paradoxical sleep, represents a smaller portion of total sleep time. Dreams or nightmares occur during REM sleep and it is associated with fast brain waves, eye movements, reduced muscle tone, and suspension of several body functions.


NREM and REM sleep cycle an average of 90 minutes and occur about 4–6 times in a good night's sleep.


According to the American Academy of Sleep Medicine, NREM sleep occurs in three progressive stages: N1→ N2→ N3 and N4, the last two of which are collectively called delta sleep or slow wave sleep (SWS).


REM sleep on the other hand occurs as a person returns to stage 2 or 1 from a deep sleep. (i.e., N1 → N2 → N3/N4 → N2 → REM)

A greater amount of deep sleep (stage N3/N4) occurs earlier in the night, while REM sleep increases in the two cycles just before natural awakening.

Watch the video below for more insight into your sleep cycle.


Video_Understanding your sleep cycle

Video: Understanding your sleep cycle




Why do you need to sleep?


Four major reasons why we need to sleep are to:

1) Clear the brain of junk and restore brain health.

2) Strengthen memory.

3) Conserve energy.

4) Restore body balance.


  • Brain health restoration

As body temperature, heart rate, and brain oxygen consumption decrease during slow wave sleep, reduced rate of metabolism occurs. This enables restorative processes to occur in various body organs but more so in the brain.

The sleeping brain has been shown to remove waste products of metabolism at faster rate than during the awake state. 


Image showing men clearing waste from a premises

Men clearing waste from a premises

Image credit: Global recycling.


Sleep may also induce the production of molecules that help repair and protect the brain from metabolic end products generated during waking.


  • Memory strengthening

It is widely accepted that sleep supports the formation and storage of long-term memory, and generally strengthens previous learning and recalls. Its benefits depend on the phase of sleep and the type of memory.

For example, memory about people, places and things (so called declarative memory) appears to improve more during early sleep when slow wave NREM sleep predominates; while memory about skills and procedures (procedural memory) are improved during the late sleep cycle dominated by REM sleep.


Like the usb storage device shown, sleep supports memory storage, strengthening and recall.

Like the usb storage device shown, sleep supports memory storage, strengthening and recall.


  • Energy conservation

During sleep the whole body is involved in lying still for considerable hours at a time.

For this reason, it is hypothesized that resting, repair and energy conservation are major reasons – but not the only reasons - why we sleep.

This makes sense if you think about it. You as a sleeper will use up less energy than someone that is awake. So, sleeping allows you to ramp down energy consumption and conserve available energy for later use.

Further evidence in support of the energy conservation function of sleep comes from the fact that even the small concentration of glycogen present in the brain relative to that in the liver increases during sleep, and is depleted through breakdown to glucose for energy during wakefulness.


Image of a sleeping African male

Sleeping African male

Image credit: Motion Array


  • Body restoration

Also, certain hormones that help growth are known to be preferentially secreted during sleep. These hormones help to repair, restore and grow body organs.

Another interesting thought here is that sleep somehow improves the functioning of the immune system.

This may help explain the observation that people who are chronically sleep deprived are about three times more likely to get sick when exposed to the common-cold virus than people who get regular eight hours sleep or more.


Torso of black male body builder from the back.

Torso of black male body builder from the back.

Image credit: Pixabay




What are the ideal and recommended duration for a good sleep?


Sleep needs vary from person to person and for different age groups.

Although researchers have found that sleeping 6–7 hours each night correlates with longevity and cardiac health in an average adult, it still must be said that there is no ideal sleep duration that applies to everyone.

Children for example spend longer hours of the day sleeping and this has been shown to influence their learning ability, language skills, attention, impulsivity level and temperament.

That said, recommendations are available for adequate sleep duration at different ages of life (see table below).


Hours of sleep recommended for each age group per day




What factors influence the quality and duration of sleep?


Studies among students in the African countries of Rwanda and Ethiopia indicate that a number of factors influence the quality and duration of sleep. Findings in these studies are also supported by those from a similar study among university students in Turkey.


The influencers of the quality and duration of sleep are best considered under the following categories:


  • Environmental

    • Exposure to tobacco smoke
      • Cigarette smoke cause irritation of the respiratory system with bouts of coughing and sputum production. These are likely to cause frequent waking episodes and disturb sleep
    • Room air quality.
      • Excessively humid, dry or dusty room air can promote breathing difficulties and disturb sleep
    • Room air temperature.
      • Excessively hot or cold room temperature may cause undue sweating or shivering respectively. Both will contribute to poor sleep quality
    • Noise
      • Noise is stress inducing and will not support quality sleep.
    • Lighting condition.
      • Bright and or flashing room lights activate the brain. They are not helpful for falling asleep early.
    • Features of the bed.
      • Mattress of the right firmness for the individual with comfortable bedding accessories help to soothe the body and enhance sleep quality


  • Psychological

    • Stress
    • Fear
    • Excitement
    • Tension
    • Doubt
    • Sadness
    • Depression


Each or a combination of these psychological factors do not promote better mental health for good sleep.


  • Biological

    • Obesity
      • This is associated with Obstructive sleep apnea – a sleeping disorder that causes frequent wakefulness due to momentary but repetitive obstruction of the breathing passage by relaxed muscles that support the soft tissues of the mouth and throat.
    • Illness
      • Short or long term illness especially when associated with pain do not promote good sleep quality
    • Fatigue
    • Diet rich in vegetables and fruits
    • Excessive eating at bed time
      • This may cause stomach bloating and indigestion. Both will disturb initiation of sleep and sleep quality
    • Hunger
      • Hunger may cause stomach pains, with irritability and therefore contribute to poor sleep.
    • Medications
      • Many medications interfere with sleep in different ways. If you are on specific medications that you link with sleep issues, talk to your doctor early.
    • Substance use
      • Like medications, many recreational substances can interfere with the initiation of sleep as well as sleep quality.
    • Smoking
    • Snoring
    • Sleep and mental disorders
      • Some mental health disorders affect sleep in many serious ways and must be treated appropriately in order to address associated sleep problems


  • Social

    • Financial distress
    • Interpersonal relationship distress
      • Family
      • Friends
      • Partner
      • Work
    • School problem
    • Loneliness


Social problems affect mental health and may directly or indirectly affect sleep quality.




What are the effects of poor sleep?


Not getting enough hours or quality sleep will impact your health in many ways, both in the short and long term.


Short-term effects of sleep problems include:

  • Poor alertness.
  • Excessive daytime sleepiness
  • Poor mood
  • Poor motor skills
  • Higher likelihood of accident if driving or operating a machine
  • Impaired memory and judgment
  • Irritability and relationship stress
  • Poor sexual health
  • Poor appetite and overall health


Long-term effects of sleep problems include:

Development of

  • High blood pressure
  • Diabetes
  • Heart attack
  • Heart failure
  • Stroke
  • Depression
  • Mental health distress
  • Reduced immunity, and
  • Poor skin health, etc.




Tips on how to sleep better


If you are having difficulty falling and staying asleep or having frequent waking episodes during sleep, try practicing these simple lifestyle behaviours (strategies) that are collectively referred to as “sleep hygiene”.


  • Make time to exercise at least 30 minutes during each day. This helps to wear your body down and makes it easier for you to fall asleep.


  • Make sleep a priority. Schedule to have at least 7 hours of sleep a night.


  • Establish a regular time to go to bed and to wake up and keep to them.


  • Prepare your body for sleeping. This may include taking a shower, brushing your teeth and changing out of your daily work dress into a dress for sleeping.


  • Avoid taking any stimulant at least two hours before your bedtime. Stimulants in this context include coffee, tea, alcohol, cigarette, etc.


  • Eat diets rich in vegertables and fruits, but avoid taking a large meal within one hour of your sleep time. This may cause bloating and indigestion and disturb your sleep.


  • De-stress by reading a book, or listening to light soothing music, or practicing breathing exercises.


  • Adjust your sleep environment. A cool, dark and noise-free room supports good sleep.


  • Use the right and comfortable beddings.


  • Remove or switch off all electronic devices in your bedroom.


  • If you do wake up during sleep, avoid looking at the clock or phone as you make effort to get back to sleep


  •  If you are unable to fall asleep after 30 minutes of going to bed, then get out of bed, go to a different room or do something relaxing that will help you get back to sleep.





Sleep is a complex biological process. It is not simply a state of inactivity with temporary shutdown of body and brain functions. It is marked by stages of specific cyclical brain activity, wave patterns and physiological processes that help growth, repair and rejuvenation of the brain and body; enhance learning and memory and boost body immunity, etc. Several factors may impact sleep duration and quality. Tips on how to get better sleep are worthy of note and practice.



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Published: February 4, 2023

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