Does sleeping late affect height? Busting growing-years sleep myths

Midnight, the bedroom light is off, but the phone screen is still glowing — a scene many parents know well. Older relatives often say "sleep late and you won't grow tall", but does sleeping until noon at the weekend make up for it? And does sleeping more always mean growing taller?

The bottom line first: sleep is a very important part of the growing-years routine, but height isn't decided by a single habit — genetics, nutrition, activity levels and overall health all play a part. Below, we use information from the Department of Health and international health bodies to bust the myths, and include a weekday routine timetable.

Key points (30-second version):

• The Department of Health's Student Health Service recommends: 9 to 12 hours a day for ages 6–12; 8 to 10 hours a day for ages 13–18.
• Sleeping and waking at fixed times — weekends and holidays included — is more practical than "catching up on sleep at the weekend".
• Put the phone away an hour before bed; try to finish dinner 3 hours before bedtime; avoid caffeine after noon.
• Sacrificing sleep before exams actually makes it easier to forget what you've revised.
• Enough sleep, plenty of movement and balanced eating need to go together; none of them alone decides height.

How are sleep and growth related?

The Department of Health Student Health Service's "Sleep-related conditions" (in Chinese) points out that good-quality sleep is an important part of children's growth and development; children in puberty and adolescence need longer, deeper sleep to release growth hormone. Another Student Health Service article, "Does sleep help with exams?", also mentions that the body secretes more growth hormone during deep sleep.

The Centre for Health Protection's "Non-Communicable Diseases Watch: Fighting obesity, let children sleep more (in Chinese)" (February 2017) also notes that most growth hormone is produced during night-time sleep; and lack of sleep is very common among Hong Kong children — a local study cited in the article found that more than half (58.4%) of the secondary school students surveyed felt they did not get enough sleep.

But note: "sleep is important for growth" doesn't equal "sleeping more will definitely make you taller". Sleep is one of the foundations, not an on/off switch for height.

Myth 1: "Catching up on sleep at the weekend is fine"

Sleeping late on weekdays and sleeping until the afternoon at weekends may seem to "balance the books", but the body doesn't count like that. The Student Health Service recommends building a regular sleep habit and going to bed and waking up at fixed times even at weekends, because good-quality sleep needs a stable body rhythm. The American Academy of Sleep Medicine (AASM)'s healthy sleep habits advice says the same: get up at the same time every day, weekends and holidays included.

The Student Health Service's "Understanding and improving your child's insomnia (in Chinese)" also reminds parents that when children sleep badly at night, don't let them get up late or nap for hours to catch up; instead, get up early together and spend 30 minutes to 1 hour in the sun, cut down on naps, and make good use of daylight to regulate sleep patterns.

Key point: rather than "paying off the debt" at the weekend, try to keep similar bedtimes and wake-up times on weekdays and holidays alike.

Myth 2: "Sleeping more will definitely make you taller"

Getting enough sleep matters a lot, but "the more you sleep, the taller you get" is an oversimplification. Growth is influenced by genetics, nutrition, physical activity, sleep and overall health together; no single habit can decide final height on its own. A more practical goal is to get "enough" sleep first, not to sleep "more" without limit.

So how much is enough? The Department of Health Student Health Service lists:

Age	Recommended sleep per day
6–12 years	9 to 12 hours
13–18 years	8 to 10 hours

Source: Department of Health Student Health Service, "Understanding and improving your child's insomnia" (in Chinese)

Everyone's actual needs differ; if a child is still often very tired after sleeping enough hours, or has long-term trouble falling asleep, see a doctor or qualified professional rather than simply sleeping longer.

How do you know if your child is getting enough sleep?

Besides hours, quality matters a lot. Drawing on the signs of poor sleep quality listed in the US Centers for Disease Control and Prevention (CDC)'s "About Sleep", plus parents' everyday observations, you can check with this list:

• Often takes a long time to fall asleep after going to bed
• Often wakes up suddenly in the middle of the night
• Still very sleepy and tired during the day despite sleeping enough hours
• Extremely hard to wake on weekday mornings, then sleeps until the afternoon at weekends
• Finds it hard to concentrate in class or on homework, and is more irritable than usual
• Snores loudly, seems to stop breathing for a moment, or makes gasping or choking sounds while asleep

Pay special attention to the last one. The UK NHS's "Sleep apnoea" notes that symptoms of sleep apnoea include pauses in breathing during sleep, loud snoring and gasping, along with feeling very tired and finding it hard to concentrate during the day; children and young people can have it too. If these happen over a long period, see a doctor for assessment.

Ticking a few items doesn't mean you need to panic straight away. As the CDC suggests, you can keep a "sleep diary": what time they went to bed, whether they woke in the night, what time they got up, and whether they napped or had caffeinated drinks — this makes it easier to explain at the doctor's.

Phones, late-night snacks, revision: 3 practical habit adjustments

The "three big reasons for sleeping late" most common among Hong Kong students can be adjusted like this:

Situation	✅ Do	❌ Don't
Phone	Put away phones and tablets an hour before bed; switch them off or keep them out of the bedroom	Reaching for the phone when you can't sleep; watching videos or gaming in bed
Late-night snacks	Eat dinner until about 70% full and try to finish 3 hours before bed; avoid coffee, tea and energy drinks after noon	Eating and drinking a lot right before bed, or "keeping going" on milk tea or fizzy drinks
Revision	Revise at a desk, set a finishing time and leave time for sleep	Revising in bed, or sacrificing sleep before exams to "squeeze in more time"

The suggestions above all come from the Department of Health Student Health Service insomnia guidance cited above: avoid electronic screen products an hour before bed, finish dinner 3 hours before bed, caffeine may take 6–8 hours to fully wear off, and avoid revising in bed. The Centre for Health Protection also recommends moving computers and TVs out of the bedroom. Parents leading by example usually works better than just telling.

Besides "when to eat" late-night snacks, there's also "what to eat" — see Does eating fried food make you shorter?

How to balance revision and sleep during exam week

Pulling an all-nighter before exams to "gain a few more hours" is common, but the Student Health Service's "Does sleep help with exams? (in Chinese)" is very clear: enough sleep before learning helps the brain get ready to form new memories; enough sleep after learning helps consolidate memories and reduce forgetting. Staying up late to study actually makes it easier to forget what you've learned, and can lead to insomnia. The Centre for Health Protection also reminds us that sacrificing sleep to gain homework time has a cost — even one hour less sleep may already affect mood and concentration.

During exam week, try arranging things like this:

1. Build sleep time into the revision timetable: set the bedtime first, then work backwards to the revision slots; don't use sleep time to "settle the account".
2. Move around when sleepy in the afternoon: try revising standing up or going for a walk; if you really need a nap, the Student Health Service says 20 minutes is enough to refresh.
3. Can't sleep? Don't scroll in bed: if you still can't fall asleep 20 minutes after going to bed, the Student Health Service recommends getting up and doing something relaxing in a dimmer setting, and going back to bed when sleepy; the AASM also reminds you not to use electronic devices during this time.
4. Too worried to sleep? Write it down: write your worries on paper, put it in a drawer, and remind yourself to deal with it tomorrow morning.
5. Get up at a fixed time during study leave too: even without school, keep your routine fixed so your body rhythm doesn't get thrown off.
6. Revise at a desk, not in bed: if you sit for long, watch your posture — see Can poor sitting posture really affect height?

Sample weekday evening routine timetable

Below is a weekday example for a secondary school student (up at 6:30 am, in bed at 10:00 pm — about eight and a half hours of sleep, within the 8 to 10 hours for ages 13–18). Primary school students need 9 to 12 hours, so bedtime should be earlier. Times can be adjusted for each family; the order is what matters.

Time	What to do	Why
18:30–19:00	Eat dinner until about 70% full	The Student Health Service recommends finishing dinner 3 hours before bed
19:00–20:45	Do homework and revise at a desk, and pack the school bag	The bed is only for sleeping
21:00	Phones, tablets and computers off; charge them outside the bedroom	Avoid electronic screen products an hour before bed
21:00–21:30	Warm shower, stretching	Relaxing activity before bed
21:30–22:00	Dim the lights, listen to soft music or read a paper book	The AASM recommends reducing bright light at night
22:00	Into bed, lights off; room dark, quiet and well ventilated	Ideal sleep environment
06:30	Get up and get some daylight; take HEIGHT+, use Mastri olive oil in everyday meals	Remember to take it during the day; keep supplements out of the bedroom

Families who take HEIGHT+ can keep the box on a surface that's easy to see during the day (such as the dining table), to help remember: "2 chewable tablets daily, ideally one in the morning and one in the evening, taken with or after meals where possible to help nutrient absorption. If the morning is inconvenient, you can also take both tablets at once in the evening. Tablets can be chewed directly, or swallowed with water if preferred." Some families also add a little Mastri Extra Virgin Cold-Pressed Olive Oil to their everyday meals. Keep the bedroom for sleeping.

Growing-years routine: enough sleep + plenty of movement + balanced eating

Sleep is only one piece. An easy-to-sustain growing-years routine can start with three things:

1. Enough sleep: follow the age recommendations above, sleep and wake at fixed times, and don't drift too far on holidays.
2. Plenty of movement: the World Health Organization's "Physical activity" notes that regular activity in children and adolescents supports bone health and muscle growth, while more sedentary time is linked to shorter sleep; the Student Health Service also says exercise helps you fall asleep, but avoid vigorous exercise right before bed. For exercising safely, see the HIIT safety guide for children and teens.
3. Balanced eating: get nutrients from a variety of foods and don't pin height on a single food — see Milk vs eggs: growing-years nutrition isn't either-or; for how to start with olive oil, see the olive oil drinking guide. See also Is olive oil suitable for cooking for children?

If everyday meals can't consistently cover the nutrients needed, some parents consider dietary supplements. BOOSTER+ HEIGHT+ growth and bone nutrition formula is a dietary supplement; how to take it: "2 chewable tablets daily, ideally one in the morning and one in the evening, taken with or after meals where possible to help nutrient absorption. If the morning is inconvenient, you can also take both tablets at once in the evening. Tablets can be chewed directly, or swallowed with water if preferred." It should be understood as coming after enough sleep, plenty of movement and balanced eating; it cannot replace any of them, and does not guarantee any growth outcome. If you have a special constitution or are taking medication, please consult a doctor or pharmacist before use.

FAQ

How many hours should children sleep each night during the growing years?

The Department of Health Student Health Service recommends 9 to 12 hours a day for ages 6–12 and 8 to 10 hours a day for ages 13–18. Actual needs vary from person to person.

Can catching up on sleep at the weekend make up for sleeping late on weekdays?

Relying on catch-up sleep is not recommended. The Student Health Service recommends going to bed and waking up at fixed times even at weekends, to keep a stable body rhythm.

Does using a phone before bed affect sleep?

The Student Health Service recommends avoiding electronic screen products an hour before bed, and switching off phones and computers where you sleep.

Can pulling an all-nighter before exams earn more marks?

The Student Health Service notes that enough sleep after learning better consolidates memory; staying up late to study actually makes it easier to forget what you've learned, and can lead to insomnia.

My child snores — should I worry?

If a child often snores loudly, pauses breathing or gasps during sleep, and is also very tired during the day, the NHS notes these may be symptoms of sleep apnoea and a doctor should assess them.

Further reading

• HIIT safety guide for children and teens
• Can poor sitting posture really affect height? A growing-years posture guide
• Does eating fried food make you shorter?
• Milk vs eggs: growing-years nutrition isn't either-or
• Olive oil drinking guide
• Busy parent who wants to look after your own daily routine? Learn about PRIMEVITA KSM-66® Ashwagandha Extract (an adult dietary supplement; pregnant women and children should consult a doctor before use).

Conclusion

Sleeping late doesn't mean "you definitely won't grow tall", and sleeping more doesn't mean "you definitely will". What's more worthwhile in the growing years is turning enough sleep, plenty of movement and balanced eating into a routine you can do every day — tonight, you can start with "put the phone away an hour before bed".

Health statement: this article is for general health education only and is not personalised medical advice. Nutritional supplements cannot replace a balanced diet or medical advice. If you have questions about a child's or adolescent's growth, sleep or health, please ask a doctor or qualified professional.

References

1. Department of Health Student Health Service, "Understanding and improving your child's insomnia" (October 2022, in Chinese): https://www.studenthealth.gov.hk/tc_chi/emotional_health_tips/parenting_tips/txt_understanding_and_dealing_with_insomnia_of_your_child.html
2. Department of Health Student Health Service, "Sleep-related conditions" (June 2020, in Chinese): https://www.studenthealth.gov.hk/tc_chi/emotional_health_tips/txt_sleep_issue.html
3. Department of Health Student Health Service, "Does sleep help with exams?" (in Chinese): https://www.studenthealth.gov.hk/tc_chi/emotional_health_tips/better_sleep/the_importance_of_sleep_for_exams.html
4. Department of Health Centre for Health Protection, "Non-Communicable Diseases Watch: Fighting obesity, let children sleep more" (February 2017, in Chinese): https://www.chp.gov.hk/files/pdf/ncd_watch_feb2017_chin.pdf
5. U.S. CDC, About Sleep (May 2024): https://www.cdc.gov/sleep/about/index.html
6. NHS, Sleep apnoea: https://www.nhs.uk/conditions/sleep-apnoea/
7. American Academy of Sleep Medicine, Healthy Sleep Habits (updated August 2020): https://sleepeducation.org/healthy-sleep/healthy-sleep-habits/
8. World Health Organization, Physical activity fact sheet (June 2024): https://www.who.int/news-room/fact-sheets/detail/physical-activity