Disclaimer: This article is for informational purposes only and isn’t intended to diagnose, treat, or replace professional medical advice. If your child experiences persistent snoring or symptoms of sleep apnoea, please speak to a qualified healthcare professional.
As a paediatrician and sleep coach, I hear the same concern from parents week after week: “My child is not growing or developing as well for their age – should I be worried?”
We talk about genetics, nutrition, and growth charts. We measure and plot and reassure. But there is one question I find myself asking more and more, and one that far too many clinicians skip entirely: How well is your child sleeping?
If that question surprises you, it should not. Because the science is clear – sleep is not simply rest. For a growing child, sleep is one of the most powerful biological events of the entire day. And when we allow our children to shortchange their sleep, we may be shortchanging their growth in ways that are measurable, meaningful, and – critically – reversible.
What happens when your child closes their eyes
Most parents think of sleep as the absence of activity. The body rests, the brain quiets, and the child recharges for the next day. But inside that sleeping child’s body, something astounding is happening.
Within the first 60 to 90 minutes of falling asleep, the brain enters its deepest sleep state – what scientists call Slow Wave Sleep, or SWS. This is the physiological sweet spot. The brain produces slow, powerful delta waves, the body temperature drops, and the pituitary gland – a tiny structure at the base of the brain – does something extraordinary. It releases the largest pulse of growth hormone your child will produce in the entire 24-hour day1.
We are not talking about a trickle. In children and adolescents, approximately 70 to 80% of the daily growth hormone output occurs during nocturnal sleep2, with the largest surge coinciding with that very first deep sleep episode. This is not a coincidence. It is biology operating exactly as designed. The sleeping child is, quite literally, growing.
But growth hormone does not work alone. It is part of a beautifully coordinated hormonal system that only comes together under the right conditions – conditions that sleep creates. Growth hormone travels to the liver and stimulates the production of IGF-1, the hormone that acts directly on the growth plates in your child’s bones3, stimulating the cartilage cells that drive linear growth. At the same time, cortisol – the hormone that normally counteracts growth – falls to its lowest level of the entire 24-hour cycle during the first hours of sleep4, creating a uniquely permissive environment for anabolism.
This coordinated state – growth hormone surging, IGF-1 rising, cortisol at its lowest point – is what is called the nocturnal anabolic window. It is one of the most important biological events in your child’s development. Although growth can occur throughout the day, it is most active during sleep.
New data from a nationwide cohort of more than 52,000 children showed that nighttime sleep duration specifically, not daytime sleep, predicts height outcomes in early childhood5. And recent population-level evidence has confirmed what the mechanistic science predicted: Reduced slow wave sleep is associated with an increased risk of short stature in children6.
The architecture of sleep matters – not just the hours
Here is where the science gets particularly important for parents to understand. It is not enough to simply get your child into bed. The timing and quality of sleep determine whether the anabolic window opens fully or not.
SWS – the deep sleep state where growth hormone surges – is front-loaded. It occurs predominantly in the first third of the night7. A child who goes to bed at 7pm and wakes at 7am gets a full, rich SWS episode within the first hour of sleep, followed by additional cycles throughout the night. A child who goes to bed at 11pm and wakes at 7am gets only 8 hours of sleep – and crucially, they miss the most physiologically potent hours entirely. The hours between 7pm and 11pm, when deep sleep would have occurred, are gone. Deep sleep will still occur in the first third of their 8-hour night, but the child will have less total time in slow-wave sleep than a child who sleeps the full developmentally appropriate hours8. There is no catch-up or compensation for a child who consistently gets 8 hours of sleep when they should developmentally get 12.
The SWS story changes across development in clinically meaningful ways. Toddlers have the highest SWS amplitude – the deepest, most powerful delta waves – of any developmental stage9. School-age children sit at a plateau of SWS architecture10, with the most consolidated, efficient sleep of their lives and the highest growth hormone pulse frequency of any age group. Their growth plates are fully open, their sleep is deep, and their bodies are primed to grow. This is the most reliable anabolic window in childhood – and it is protected by one simple thing: A consistent, early bedtime.
Adolescents face the greatest challenge. Their GH pulse amplitude reaches its lifetime maximum – gonadal steroids during puberty amplify growth hormone surges to two to three times the school-age levels11. The hormonal drive to grow has never been stronger. But this is precisely when sleep becomes most vulnerable. A biologically driven phase delay pushes teenagers toward later and later bedtimes. School obligations force early wake times. The result is chronic restriction of SWS during the developmental window when the stakes are highest. The hormonal accelerator is floored – but the engine is running on empty.
The hunger hormones make it worse
Sleep affects more than just growth hormone. When a child does not get enough sleep, two other hormones shift in ways that compound the problem.
Leptin – a hormone produced by fat cells that normally peaks during sleep – supports growth hormone secretion by putting the brakes on a hormone called somatostatin12 (a mechanism demonstrated in animal models). When sleep is cut short, leptin peaks are blunted, and growth hormone pulses become smaller and less frequent13.
At the same time, ghrelin – the hunger hormone – rises significantly with sleep restriction14. Although ghrelin’s dominant daytime effect is appetite stimulation15, children with suboptimal sleep feel hungrier, crave higher-calorie foods, and are more likely to reach for sugary snacks during the day and late at night. The link between short sleep and elevated ghrelin has been confirmed by meta-analysis16. Those late-night high-glycaemic snacks trigger an insulin response that activates somatostatin, further suppressing the growth hormone pulse they desperately need. The result is a double hit. Impaired growth potential on one side and increased obesity risk on the other – a plausible but still-developing area of paediatric research17. Both may be driven by the same root cause: Not enough sleep.
What you can do tonight
The good news is that the nocturnal anabolic window opens every night. Our job as parents – and as clinicians – is to help our children keep it open.
Here is what the science supports:
Protect the bedtime: The American Academy of Sleep Medicine, in consensus with the American Academy of Pediatrics, recommends 9 to 12 hours of sleep for school-age children (ages 6 to 12) and 8 to 10 hours for adolescents¹⁸. For younger school-age children, a 7pm bedtime is not old-fashioned – it is biology. Every hour of delayed sleep onset can be an hour of delayed growth hormone secretion1.
Guard the pre-sleep window: Avoid high-glycaemic foods including sugary snacks, juice, and sweetened cereals in the 2 to 3 hours before sleep19. These foods trigger the insulin response that suppresses growth hormone. Instead, offer a small serving of low-glycaemic protein, such as a glass of plain milk or a small portion of yogurt, that may support overnight anabolism by providing amino acids for growth without disrupting the hormonal environment.
Create the right environment: A dark, cool room — ideally 65–68°F (18–20°C) – supports deeper sleep. Eliminate screens at least 60 minutes before bed. Blue light from phones and tablets actively suppresses melatonin, delaying sleep onset and shortening the anabolic window. Keep all devices outside of the bedroom – for all age groups, but especially children and teens.
Ask the hard questions: Red flags for poor sleep that warrant medical evaluation include snoring, gasping, restless sleep, or difficulty waking in the morning. Obstructive sleep apnoea fragments deep sleep, blunts growth hormone secretion, and can significantly impair growth velocity; however, treating it with adenotonsillectomy has been shown to restore growth hormone secretion and growth20. Even one week of restricted sleep has been shown to cause measurable hormonal disruption4. Children with diagnosed sleep disorders have higher rates of both short stature and excess weight than their peers21. If you notice these signs, speak to your paediatrician about a sleep evaluation.
A final word
When I counsel families about sleep, I want them to leave with one image in their minds: Their child, in the quiet dark of the early morning hours, bones lengthening, proteins being built, memories consolidating, moods shifting, and growth hormone doing exactly what it was designed to do. That image is not only a beautiful symphony of human development but also a basic physiology lesson. It is happening right now in every well-sleeping child.
Again, sleep is not the absence of the day; it is when growth happens. It is not something to begrudgingly do when we are finally bored with everything else or when our body cries out for sleep from pure exhaustion. Sleep is what our bodies demand, on par with food, water, and air. It is an absolute requirement for survival and for becoming the best you can be. When we protect our children’s sleep – consistently, intentionally, and early – we are not just helping them feel better in the morning; we are giving them the biological conditions they need to grow into their full potential.
Give your child a growing chance. Let them sleep!
Dr. Nilong Vyas is a board-certified paediatrician, founder of Sleepless in NOLA, and a nationally recognised expert in paediatric sleep and nutrition. She works with families across the United States and internationally to optimise sleep for children of all ages and developmental needs. Learn more at sleeplessinnola.com
Learn more about sleep or take our interactive snoring test
Kawai M, Baba S, Tanigawa K, et al. (2025) Association of nighttime sleep duration at 1.5 years with height at 3 years: The Japan Environment and Children’s Study. Journal of Clinical Endocrinology & Metabolism, 110(6):e1866–e1873. https://pubmed.ncbi.nlm.nih.gov/39288009
Chen Z, Shi Y, Lei F, et al. (2025) Reduced slow wave sleep is associated with increased risk of short stature in children: a cross-sectional study. Nature and Science of Sleep, 17:2957–2967. https://doi.org/10.2147/NSS.S475390
Dijk DJ, Czeisler CA. (1995) Contribution of the circadian pacemaker and the sleep homeostat to sleep propensity, sleep structure, electroencephalographic slow waves, and sleep spindle activity in humans. Journal of Neuroscience. https://www.jneurosci.org/content/15/5/3526
Ohayon MM, Carskadon MA, Guilleminault C, et al. (2004) Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals. Sleep. https://pubmed.ncbi.nlm.nih.gov/15586779
Buchmann A, Ringli M, Kurth S, et al. (2011) EEG sleep slow-wave activity as a mirror of cortical maturation. Cerebral Cortex. https://pubmed.ncbi.nlm.nih.gov/20624840
Campbell IG, Darchia N, Higgins LM, et al. (2011) Adolescent changes in homeostatic regulation of EEG activity in the delta and theta frequency bands during NREM sleep. Sleep, 34(1):83–91. https://pmc.ncbi.nlm.nih.gov/articles/PMC3001800
Martha PM Jr, Rogol AD, Veldhuis JD, et al. (1992) Alterations in the pulsatile properties of circulating growth hormone concentrations during puberty in boys. Journal of Clinical Endocrinology & Metabolism. https://pubmed.ncbi.nlm.nih.gov/1730812
Tannenbaum GS, Gurd W, Lapointe M. (1998) Leptin is a potent stimulator of spontaneous pulsatile growth hormone secretion and the GH response to GH-releasing hormone. Endocrinology. https://pubmed.ncbi.nlm.nih.gov/9724042
Spiegel K, Tasali E, Penev P, et al. (2004) Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Annals of Internal Medicine. https://pubmed.ncbi.nlm.nih.gov/15583226
Kojima M, Hosoda H, Date Y, et al. (1999) Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. https://www.nature.com/articles/45230
Lin J, Jiang Y, Wang G, et al. (2020) Associations of short sleep duration with appetite-regulating hormones and adipokines: a systematic review and meta-analysis. Obesity Reviews. https://onlinelibrary.wiley.com/doi/10.1111/obr.13051
Hagen EW, Starke SJ, Peppard PE. (2015) The association between sleep duration and leptin, ghrelin, and adiponectin among children and adolescents. Current Sleep Medicine Reports, 1(4):185–194. https://link.springer.com/article/10.1007/s40675-015-0025-9
Paruthi S, Brooks LJ, D’Ambrosio C, et al. (2016) Recommended amount of sleep for pediatric populations: A consensus statement of the American Academy of Sleep Medicine. Journal of Clinical Sleep Medicine. https://jcsm.aasm.org/doi/10.5664/jcsm.5866
Nieminen P, Löppönen T, Tolonen U, et al. (2002) Growth and biochemical markers of growth in children with snoring and obstructive sleep apnea. Pediatrics, 109(4):e55. https://pubmed.ncbi.nlm.nih.gov/11927728
