Healthy Sleep Habits, Happy Child
Sleep Duration, A Review
June 26, 2023

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Healthy Sleep Habits, Happy Child

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A Healthy Child Needs a Healthy Brain, A Healthy Brain Needs Healthy Sleep

If you have not already done so, please read Blog Posts 1 through 5 that describe how sleep is important and beneficial. I will post specific information for parents and children based on my book, “Healthy Sleep Habits, Happy Child.” Please do not be put off by my book’s length. This is a reference book. Read only the topic of interest to you.

Blog 137Sleep Duration, A Review

Sleep duration is paramount because the health and function of the brain is primarily a direct function of the amount of sleep obtained-the more sleep obtained the better.”

“Cognitive ability and readiness vary as a direct function of the amount of sleep obtained.  The more sleep Soldiers [or children] get, the greater their mental acuity, with faster response times, fewer errors, and fewer lapses in attention. Also improved are judgement, problem-solving, situational awareness, mood, resilience, and general well- being.”

The relationship between sleep duration and cognitive readiness (and thus military effectiveness) is best thought of as a continuum, with more sleep always producing improved performance.”

“Even for those who regularly obtain the generally recommended number of hours of sleep per night, more sleep can result in even better alertness and mental acuity. Insufficient sleep degrades the brain’s function. The more sleep the brain gets, the better it functions. Insufficient sleep negatively effects not only cognitive performance, but emotional and social functioning. In short, the brain has a physiological need for sleep, and sleep promotes the ability to think and maintain mental toughness. And the more sleep, the better. Although obtaining ample and regular sleep generally results in the ability to sustain normal levels of alertness and performance during the daytime, obtaining even more sleep results in greater brain readiness-enhanced mental sharpness and resilience in the field.”

So, more sleep produces more benefits for children. Even small amounts of extra sleep help. At every age!



There are four types of studies proving that just small amounts of extra sleep help children.  All these papers were published in peer-reviewed scientific journals.

  1.  Moving middle-school and high-school start times later allows students to sleep in later and get more sleep. 
  • Delaying school start times caused 15-year-olds to sleep in later and five months later, they demonstrated improved mental health, better prosocial behavior, peer relationships, and attention level but the average increase in night sleep was only 2 minutes
  • Lower levels of sleepiness and improvement in alertness and well-being among 15-year-olds was observed in another study of delaying school start times.  The increase in night sleep time after nine months was just 10 minutes.  Similar results were observed in three other studies involving delaying school start times with an additional 17 minutes, 29 minutes, and 34 minutes more sleep producing less sleepiness, less tardiness, and increase in grades.
  • In an additional study, a 15-year-old was “classified as having low mood if he answered “yes” to the following question: During the past 12 months, did you ever feel so sad or hopeless almost every day for two weeks or more in a row that you stopped doing some usual activities?”   Delaying the school start time caused a significant reduction of almost 5 per cent of the prevalence of low mood with a 30-minute increase in sleep duration.  Also, in this study, among 13-year-olds, starting school earlier caused a decrease of sleep duration of 15 minutes and a 2 per cent increase in low mood prevalence.   
  • A 2022 study showed that when the school start time was move to a later hour, students in middle school and high school obtained 31 minutes extra sleep.  This caused a significant decrease in the students experiencing symptoms of depression or anxiety.

2. Experiments in sleep laboratories using either sleep extension or sleep restriction.

  • Experimentally extending sleep by adding one hour in bed for five nights caused adolescents to sleep 13 minutes more at night with a reduction of insomnia and depressive symptoms.
  • Separately, adding one hour in bed for five nights in children 7 to 11 years-old provided an additional 27 minutes of sleep with improvements in emotional lability and restless-impulsive behavior.  

3. Studies focused on concurrent effects. 

  • Parent-set bedtimes among 14-year-olds caused an earlier bedtime which was associated with an extra 19 minutes of night sleep which caused improved daytime functioning.  
  • A study of 7 to 11 years-old showed that 18 minutes of extra sleep caused improvement in grades for mathematics and languages.
  • A 2022 paper, titled ‘Association between sleep duration and Intelligence Quotient in 6-year-old children concluded: “The results of this study support an association between longer sleep duration and increased IQ scores.”
  1. Studies of longitudinal outcomes.
  • When 6- and 8-year-olds sleep 30 minutes less than their peers, they are more likely to have symptoms of psychiatric disorders two years later.  
  • In a 2021 study of 315 children, between 2-6 years, over a 15-month follow-up period, the assessment of night sleep duration showed a significant dose-response trend for subsequent changes in measurements in four domains: hyperactivity/inattention, conduct problems, peer relationships, and prosocial behavior.  “Compared with children who decreased or had no change in nighttime sleep duration from baseline to follow-up [15 months later], those children who increased their sleep duration had a concurrent decrease in measurements [less hyperactivity/inattention, fewer conduct problems, better peer relationships, more prosocial behavior].  



Also, mothers benefits when her child gets more sleep!

  • A 2021 paper described how Iranian infants were helped to sleep better and how this improvement in their sleep improved their mother’s mental health.

“In Iran, most mothers are housewives, and they usually have a late wake time of around 10:00am and naturally their infants sleep more in the morning and afternoon.  On the other hand, most men come back home very late (around 8:00pm or even later) and play with babies after this time.  In addition, most small family gathering parties (a widespread activity in the Iranian daily schedule) are held at night, and babies are one of the most important members of these parties.  Considering the average Iranian adult bedtime (about 11:00pm), children also often have a late bedtime like most Asian and Middle eastern countries.”  They studied a group of infants 2-4 months of age and randomly divided them into a sleep intervention group that received guidance on healthy sleep and a matched control group that received information on general safety.  Surprisingly, 94% of all infants in the study had a bedtime at baseline later than 11:00pm and the range of it was between 10:00pm and 4:00am.

After 8 weeks, in the sleep intervention group:

The bedtime shifted from 1:00am to 10:20pm.

Night sleep duration (sleep between 10:00pm and 8:00am) increased by about 1.5 hours.

Longest sleep period without signaled awakenings increased by about 1 hour.

Maternal sleep quality improved.

Maternal postnatal depression decreased.

  • A 2022 study evaluated, “Factors associated with maternal overall quality of life six months postpartum” from Norway and included almost 90,000 mothers and children.  

The mother’s ‘overall quality of life’ was measured by her agreement or disagreement with five questions: 

  1. In most ways my life is close to my ideal.
  2. The conditions of my life are excellent. 
  3. I am satisfied with my life.
  4. So far, I have gotten the important things I want in life.
  5. If I could live my life over, I would change almost nothing.

Mothers’ overall quality of life was associated with joy of motherhood, relationship satisfaction, and especially, long infant sleep duration.

Remember, the brain is the only organ in the body that has sleep as a requirement. Long sleep comes from an early bedtime (Blog Posts 7, 74, and 109). Even just a few minutes of extra sleep makes a big difference (Blog Post 6)!

More information about child and baby sleep training:

Brain health depends on healthy sleep. More sleep is better. Blog Posts 15

Just move the bedtime a few minutes earlier to get more sleep for your child. Blog Posts 7, 69, 123, and Sleep Tip

More sleep makes your child’s temperament easier. Blog Post 48

More sleep may cure a “mental health problem”. Blog Post 66

In young children, adverse effects from mild unhealthy sleep are reversible. Blog Posts 5051 and Parents’ Reports

Over a long time, adverse effects from severe unhealthy sleep may become irreversible. Blog Posts 5051

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