What is the relationship between sleep and brain development in infants and young children?

A large amount of research has been done on the effects of sleep and brain development in the history of mankind, however there have been substantial leaps of late.  The effects of poor sleep in infants later in life have been touched on, however there is still a lot that needs to be determined due to the fact that these studies are longitudinal in nature.  What we do know for sure that is that the early years in life, especially the first 3 are exceptionally important in the development of a Childs’ brain.  Everything he or she sees, touches, smells and/or hears helps to shape the brain for thinking, feeling, moving and learning  (Factsforlifeglobal.org, 2017).  In these first 3 years of life, the brain undergoes an amazing period of development where more than 1 000 000 million neural connections are formed each second  (Zero to Three, n.d).

Babies have large heads in order to accommodate their rapidly growing brains.  At age 2, the brain is already 80% of the size of an adults’ brain (Faculty.washington.edu, 2017)  Brain development happens in stages, with different parts of it growing and developing at different points in time. (www.ag.ndsu.edu, 2017)  Something to take into consideration is that most of the brain cells are formed before birth, however most of the connections, or synapses in the brain are formed in infancy and early childhood.  This brain development allows the child to then crawl, eat, sleep, walk, and talk etc. (www.ag.ndsu.edu, 2017).

 

Facts about the human brain

The Human brain is without a doubt, one of the most, if not the most interesting organ in the body.  It processes so much information each second that it is almost incomprehensible to most layman.  The human brain is made up of 100 billion neurons and about a trillion glial cells (Popular Science, 2017).  The brain, representing only 2% of the total body weight, consumes the most energy generated by the body – a total of about 20% of all energy generated by the body.  (Epyk – Health and Fitness, from exercise to Food, 2017)  Another interesting fact is that 95% of our thoughts and decisions happen in the subconscious mind  (Mahoney, 2017).

In babies, the brain starts developing 3 weeks after conception (Zero to Three, n.d.).  In fact, an infant has more brain cells at birth than they will have for the rest of their life (Popular Science, 2017).  An infant’s mind is primed for learning when born, and synapses and connections are formed based on what they experience (www.ag.ndsu.edu, 2017).  That is also often why people refer to babies’ and young children’s minds as sponges.

As far as sleep goes – the lack thereof affects the brain in multiple ways that can impair judgement and cause slow reaction (Kurzweil and Grossman, 2017).  In fact, to the human brain, 1 sleepless night is the cognitive equivalent of being legally drunk.

 

What happens to the infant brain during sleep?

A baby’s brain can use up to 50% of their total glucose supply, which may be the explanation as to why they sleep so much  (Kurzweil and Grossman, 2017).  Early experiences affect the development of the brain’s architecture, which provides the foundation for all future learning, behaviour and health.  Just as a weak foundation compromises the strength of any structure, adverse experiences in early life can impair brain architecture, with negative effects lasting an entire lifetime (Center on the Developing Child at Harvard University, 2017).  A remarkable increase in synapses occur during the first 3 years of life.  The brain develops a functional architecture through the development of these synapses and connections.  Connections are formed by the environment and experiences, so as an example if the parent repeatedly calls the child by a certain name, the brain will form a connection accordingly.  By the time a child is 3 years old, a baby’s brain has formed around 1 000 trillion connections which is about twice as many as the average adult.  The baby’s brain is super dense and will remain this way for about the first 10 years of life.  Around age 11, the brain starts getting rid of unnecessary connections in a process called pruning which happens gradually and allows for the remaining connections to be more effective and powerful (www.ag.ndsu.edu, 2017).

Researchers at the University of Colorado Boulder have discovered that when babies and young children are sleeping, their brain is busy building and strengthening connections between the left and the right hemisphere of the cerebrum.  These thick connections facilitate communication between the 2 hemispheres.   Another study done in October 2013 linked Albert Einstein’s brilliance to well-connected brain hemispheres.  As we get older, these connections that were formed in childhood, serve as the infrastructure to lay down more complex neural connections throughout the individuals’ life.  Having both brain hemispheres symmetrical and well connected is the key to maximizing learning, memory and creativity  (Bergland, 2013).

What is also seen in children is a high rate of neuroplasticity.  This relates to structural and functional changes in the brain brought on by training and experience.  It refers to the brain’s ability to change by creating additional grey matter and by altering synapses.  It appears that the most crucial time for these changes are in the first 3 years of life, with adults and older children only being capable of these changes on a much smaller scale.  This is one of the reasons why small children recover from brain injuries more completely than adults.  It also explains how a 3 or 4 year old can still develop normal language abilities even when the entire left hemisphere of their brain has been removed.  In addition, recent work has shown that cerebral proteins are produced during sleep, aiding in the aforementioned changes  (Robert Rosenberg, 2017).

 

Why is sleep so important for children?

A study conducted in Feb 2013 confirmed that our brains store what has been learnt during sleep. In children, this is an even more effective process than in adults according to Doctor Ines Wilhelm of the University of Tubingen’s institute of medical psychology and behavioural Neurobiology (The sleeping child outplays the adult’s capacity to convert implicit into explicit knowledge, 2013). Further to this, Doctor Wilhelm also said:  “In children much more efficient explicit knowledge is generated during sleep from a previously learned implicit tasks.  And the children’s extraordinary ability is linked with the large amount of deep sleep they get at night.”  In conclusion, he added “The formation of explicit knowledge appears to be a very specific ability of childhood sleep, since children typically benefit as much or less than adults from sleep when it comes to other types of memory tasks.”  In addition to this, the ration of 1 hour sleep for every 2 hours of being awake is programmed into our biology and is required for survival and performance  (Bergland, 2013).

In a British medical journal, in an article published in 2013, there is a report on a study that demonstrates the relationship between sleep and brain development.  This study, called the Millennium cohort study, followed 11 000 children, and found that children with irregular bedtimes from birth to age 3 were negatively affected in skills pertaining to reading, maths and spatial awareness.  As researchers continued to follow these children, they continued lagging behind by age 7, with girls being more affected than boys.  This demonstrated that sleep plays a critical role in brain development in the first 3 years of life.   There were similar findings in a different study published in the journal, “Sleep” in 2008.  This study found that sleeping less than 10 hours per night from birth to age 3 caused a higher likelihood of language and reading problems as well as ADHD.  It was also found that these problems persisted later into life  (Robert Rosenberg, 2017).

Further to the importance of sleep and brain development, sleep has also been linked to learning, growth and heart health  (Superior North Catholic District School Board, 2017).  Due to the fact that knowledge is converted to memory whilst we sleep, it also affects memory, not only due to the conversion, but also because it is difficult to concentrate when you are tired (Healthysleep.med.harvard.edu, 2007). Sleep also restores energy in young children, which is really important for various reasons, including being a healthy and active child  (BabyCenter, 2017).

Further tests were done and research has proven that inadequate and poor sleep quality affected children’s performance in intelligence tests.  13 children with autism as well as 13 children with no learning or social disabilities were followed in this study.  “It was found that disruptions in the protective brainwaves during sleep are associated with lower results in verbal IQ tests.  Godbout added that the study established that children and adolescents are particularly affected by lack of sleep, especially because they are in an important developmental period.” (Indiatoday.intoday.in, 2015). Another paper published by Touchet et al, stated that short sleep duration in the first 3 years of life was associated with hyperactivity, impulsivity and lower cognitive performance on neurodevelopmental tests at the age of 6  (Dahl, 2007).

 

What is normal and how much do they need?

Being well informed of your children’s milestones can assist you in being the best parent you can be by empowering you to know what to expect at which stages of development and allowing you to prompt and follow up should your child not reach these when expected.  According to Urbanchildinstitutes.org (2015) the below is to be expected in the 1st year of life.

 

 

In addition to the above, it is great to take not of the fact that there are prime times for certain parts of development.  (Brotherson, 2009)

  • 4 – 5 Years – Prime time for visual and auditory development
  • Birth – 10 Years old – Prime time for learning to speak and language development
  • Birth – 12 Years old – Prime time for physical and motor development.
  • Birth – 12 years old – Prime time for emotional and social development
  • Birth – 18 months – Prime time for the forming of emotional attachment. This period acts as the foundation of other aspects of emotional development.

Baby centre in the UK recommends that you follow the below guide to the amount of sleep required by your baby. (BabyCenter UK, 2016)

 

Conclusion

Even though there are commonalities in young children with regards to when they are supposed to reach certain milestones, we need to keep in mind that each child develops at his or her own pace.  Every child has their own interests, temperament, style of social interaction and approach to learning (Factsforlifeglobal.org, n.d).  In addition to this, there are many external factors that play a role.   Lifestyle factors such as long days at work, early school start times, hectic extracurricular activity schedules and various other commitments cause for bedtimes to be pushed backs and young children to miss out on some of their naps – this isn’t because we don’t care, but because there are sometimes things that happen that we don’t have control over.  The unfortunate thing is that all of these factors can have an effect on brain development and may even have effects that last a lifetime  (Superior North Catholic District School Board, 2017).

It has to also be taken into consideration that babies have their own sleep personalities.  Scott Cohen, a paediatrician and author of Eat Sleep Poop: A Common Guide to Your Baby’s First Year, states “There are definitely individual differences in how babies sleep, just as there are light sleepers and heavy sleepers amongst adults.”  He added that parents of multiple babies may see differences quite early in their children’s lives, as well as the fact that personalities come into play.  Babies with stronger personalities may fight sleep for longer periods of time, making it harder for parents to get them down to sleep, whilst other babies might be more easy-going.  He actually refers to the baby sleep lottery  (Lack, 2016).

Dahl, (2007) states “Broadly speaking, it might be argued that the most fundamental requirements for healthy growth and development in young children include a) loving support and protection by parent/caretakers, b) adequate nutrition, and c) adequate sleep.” Doctor Dean Beebe, director of the Neuropsychology program at Cincinnati Children’s Hospital medical centre, says “First, inadequate sleep causes everyone, including children, to be biased towards seeing the world in a more negative light and less in a positive one.”  He adds that inadequate sleep, whether too short or poor quality, cause specific changes in mood and thinking.  It can also cause issues with regulating moods, in both children and adults.  “Children who don’t get sufficient sleep at night, are more likely to be overactive and non-compliant, as well as withdrawn and anxious.” (Beebe, 2012).

We need to take into consideration that there is much research still to be done in this field and there is still much to be discovered.  It is a fact though that researchers continue to discover the importance of a good night’s sleep in the development and functioning of the human brain, especially in young children  (Bergland, 2013).

If you suspect that you baby is routinely overtired and you find it hard to awaken your baby, it will be worth talking to your physician about it as there may be other health issues that need to be looked at says Doctor Gwen Dewar  (Dewar, 2014).

 


Definitions:

Synapses:  the point at which a nervous impulse passes from one neuron to another.  (Merriam-webster.com (2017)

Neuroplasticity:  The ability of the brain to form and reorganize synaptic connections, especially in response to learning or experience or following injury.  (Oxford Dictionaries I English, 2017)

Myelin:  a substance containing a lot of fat that forms a covering around nerves, especially those in the brain, protecting them and helping them to send signals effectively. (Dictionary.cambridge.org, n.d)

Cerebrum:  The anterior and largest part of the brain, consisting of 2 halves or hemispheres and serving to control voluntary movements and coordinate mental actions; the forebrain and the midbrain.  (Dictionary.cambridge.org, n.d).

Implicit knowledge:  All knowledge that is not explicit knowledge. Also Tacit knowledge; knowledge that you do not get from being taught, or from books, but from experience.  (Dictionary.cambridge.org, n.d)

Explicit knowledge:  Knowledge that can be expressed in words, numbers and symbols.  Stored in books and computers etc.  (Dictionary.cambridge.org, n.d)

 


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