More science of sleep in childhood and adolescence: a handful of new (or new-ish) studies and reports
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In the last few weeks I’ve presented at a number of school “acquaintance” and “orientation” nights to parents of primary and secondary students – and one of the topics I cover in these seminars is sleep: how much children and teens need and how we support them to get enough.
It’s only a small part of the talk (I discuss a range of factors which are associated with success and wellbeing for young people) but I thought I’d do some reading to make sure I was across any significant developments in the science of sleep for young people.
Once I started reading, I went down the “reading research rabbit hole”. I spent a few hours (and missed some of my own sleep time) reading some interesting new studies and reports – as well as some old ones I’d missed.
I thought some of them might be worth sharing with you in this article. Here they are, in no particular order:
1. Changed recommendations for how much sleep children and teens need
In 2015 (I know 5 years ago, but in case you’d missed it) the US based National Sleep Foundation “widened” their recommendations for how much sleep is needed by children and adolescents (and these were then accepted by Australian Sleep associations too).
They wanted to acknowledge there is more individual variation than previously thought regarding the amount of sleep required for young people. The changed recommendations were as follows:
For Preschoolers (3-5): The sleep range was widened by one hour to be 10-13 hours (previously it was 11-13 hours).
For School age children (6-13): The sleep range was also widened by one hour to be 9-11 hours (previously it was 10-11 hours).
Teenagers (14-17): Sleep range was again widened by one hour to be 8-10 hours (previously it was 8.5-9.5 hours).
By the way, when I talk with families about working out how much sleep their own individual children and teens need, I often ask about morning sleepiness. Although we have a “sleep inertia” when we first wake up, kids and teens (and adults) should not feel sleepy once they have been awake for 45 minutes. If they are feeling sleepy at that point, this is a good indication they haven’t got enough sleep.
2. How much sleep do Australian kids and teens actually get?
The Longitudinal Study of Australian Children (I’ll call this the LSA 2019 from now on) is a huge data collection of over 10,000 kids and families and the Australian government produced a report just last year about sleep in this age group.
This report stated that most Australian children aged 6 to 11 were getting between 10 and 10.5 hours per night on school nights. Thus, on average, children of this age were meeting national recommendations for sleep quantity (at least on school nights).
However in teenagers the data told a different story. A quarter of Australian 14-15 year olds and a half of 16-17 year olds were not meeting the national sleep recommendations for this age group.
It should be noted that some were getting more than they needed, meaning the average sleep time for 14-15 year olds was 8.5 hours and for 16-17 year olds the average was just over 8 hours (all on school nights).
Here are the average sleep times, by age group.
3. What time do kids and teens in Australia go to bed?
The LSA 2019 report also concluded that 6 to 11 year olds in Australia go to bed on average between 8 and 8.30pm, 12-15 year olds go to bed between 9 and 9.30pm and 16-17 year olds go to bed between 10 and 10.30pm. I’ve included the chart below with the times for each group.
As you read these bedtimes, keep in mind that the average “sleep onset latency” (how long it takes young people to actually get to sleep) was also measured in this study - on average it was taking between 20 and 40 minutes for children to fall asleep, with younger children being on the shorter of this scale and adolescents being on the longer end of this scale.
It can be useful for us to explain this idea of “sleep onset latency” (or for kids: “sleep preparation time”) to young people – to provide them with a rationale for why we need to stay still and quiet, with ‘slow mind’ for at least 20 minutes. This is a tough ask for some kids/teens (and I think possibly even more so in our current world of technology providing us with constant stimulation) so it’s important for us to patiently and kindly helping young people practice this.
4. Possible increases the number of teens who are sleep deprived – is this responsible for increases in mental health challenges in teens in our society?
A researcher called Jean Twenge looked at data from two longitudinal studies of teen sleeping patterns in the US and she found that 40 percent of adolescents in 2015 slept less than 7 hours a night. What was even more interesting however was the data she analysed which showed there had been a 58 percent increase in the number of adolescents getting less than 7 hours a night since 1991, and a 17 percent increase in the number of teens getting less than 7 hours a night since 2009.
It appears we may have a generation of young people who are sleeping much less than those in previous generations. Given the clearly documented links between sleep quality and length and well-being (see below for more on this), many psychologists are talking about whether the increase in mood problems in young people shown in some studies over this period of time can be directly attributable to the less sleep they are getting.
5. Yet more studies in the last year linking sleep and mental health challenges
A study just published a few weeks ago in January 2020, found links between the amount of sleep primary aged children get and their behavioural and mental health, as well as the size of a number of their brain structures associated with emotion control and learning. Shorter sleep duration was linked in 9 to 11 year olds with scores on tests of depression, anxiety, impulsive behaviour and cognitive (learning) tests.
Another set of researchers from Berkley Uni just last year also focused on sleep and mental health but in their study considered anxiety in particular. They asked young people (18 year olds) to have a brain scan and then watch emotionally disturbing videos - after either getting a full night of sleep, or an interrupted night of sleep.
The scans showed that on the day after an interrupted night of sleep, a part of the brain called the “medial prefrontal cortex – which often helps manage anxiety – was ‘shut down’ (less activity), and at the same time the brain’s deeper emotional centres were more active than usual. The young people reported more anxiety during this day, and when they watched the emotionally disturbing video – they experienced a higher level of distress and anxiety. When the young people had a full night of sleep, these findings were diametrically opposite: a full night of sleep resulted in less activity in emotional centres, more activity in the parts of the brain which manage anxiety, and less distress after watching a video. All of this was particularly true for those young adults who experienced more “slow-wave NREM” sleep – ie deep sleep – in the previous night.
As well as these experimental studies, these very same researchers conducted an online study simultaneously (over-achievers clearly) asking 280 people (of all ages) to record sleep and anxiety levels over 4 days. The results showed that the amount and quality of sleep people had each night predicted their anxiety the next day – and this was true even for small changes in sleep amounts.
I’ve read a lot about the links between mental health and sleep over the past few years – but this particular study made me raise my eyebrows – it was very compelling evidence to suggest sleep deprivation can be a clear cause of anxiety. In other words, when we don’t sleep the previous night, we are more likely to feel much more anxious – regardless of whatever else is going on in our lives that day.
6. Anxiety isn’t the only mental health challenge linked to sleep problems
Anxiety isn’t the only area of ‘mental health – sleep’ relationship which is being currently examined. Last year (2019) researchers from Cincinnati Children's Hospital Medical Center asked teenagers who had been diagnosed with ADHD to spend a week restricting their sleep to 6.5 hours per night, followed by a week in which they could sleep up to 9.5 hours per night. After the week of less sleep they had significantly lower scores on a test of attention, planning, concentration compared to the week of more sleep.
This is an interesting study suggesting two slightly different, but related ideas: a) sleep deprivation may be partly a cause of attention and concentration problems for teens diagnosed with ADHD; and b) “increasing” sleep in teens with attention and concentration problems may be a useful treatment for them.
7. Technology use and sleep problems – more research linking the two
There have been many studies linking screen time with poorer sleep in young people over the last two decades, however I like to keep reading about this research because the nature and type of screen time has changed so significantly in our society.
For instance, what we were doing on screens and how we are doing it five years ago is very different to what we are doing now – and the different technology behaviours may have very different implications (some young people are using their phones to access sleep meditation apps just to take one example).
As a result, I think the research in this area needs to be recent in order for us to draw real world conclusions from it. So I was interested to see another study from only 18 months ago (2018) in which 2,865 adolescents were asked about problems falling and staying asleep, their mood and how long they slept during the week. They were also asked about the typical daily hours they spent on social messaging, web surfing, TV/movies, and gaming. The results of this study showed that symptoms of depression and difficulties getting to sleep were linked with higher numbers of hours of technology use.
I’m assuming this is not going to be a surprise to many. Almost every parent I speak to is very aware that helping kids and teens balance the use of technology in their lives is vital (and extremely demanding). However the results of this study gives just another reason for us to prioritise this (hard, exhausting) work we do.
8. Specific bedtimes set by parents/caregivers seem to help – even for older teens
I’m often talking with parents/caregivers of teenagers who tell them “no-one else my age has a bedtime”. A study published in late 2019 found that in the US at least, this isn’t quite true. This study interviewed teenagers (14-17 year olds) and parents and found that about 44% of families reported that they had “enforced” bedtimes for their young people of this age.
These families reported more bedtime conflict – not surprisingly. But these teenagers got significantly more sleep than those teenagers whose parents did not have these enforced bedtimes, had significantly higher day time energy and significantly lower depressive symptoms.
One final point about this study – contrary to what the researchers expected, evening screen time was NOT linked to how much sleep the teens got. More research on this last aspect is needed, as it contradicts some other research in this area – including one of those in the paragraphs above (which looked at screen time throughout the day – not just in the evening).
9. Routines help for younger children
A study of 10,000 mothers from 14 countries who were asked about their children’s (aged 6 and under) sleep found that mothers who said their children who had a consistent bedtime routine (same actions before bed, with bedtime at the same time) also reported that their children were getting longer periods of sleep than those without a routine – and also that the more nights per week parents/caregivers reported “following” the routine, the more sleep the children got.
I found this an interesting study as it looked at sleep habits of children in several different countries around the world – it is possible that “bed time routines” is a cross-cultural phenomenon that helps young people get more sleep.
10. More physical activity seems to be associated with better and more sleep in young people
The LSA (2019) found that children and teens who played sport got more sleep than those who didn’t do so. This corresponds to a study from 2013 which found that every minute additional physical activity during the day for primary aged children resulted in a shorter period of time taken to fall asleep that night.
Both of these pieces of research suggest that we need to keep on trying to help young people be involved in sport and physical activity (not easy for some young people – including those with disabilities which make this harder – but still worth working on).
11. Sleep problems are probably at least partly genetic – a reason to ease up on the parent guilt/parent /teenager blaming
Do you have a young person who gets less sleep than you think they need and are feeling like it’s your/their fault? Here’s something which might be some help: A large study from last year found that sleeping problems have a strong genetic component. Researchers at the University of California looked at DNA samples obtained from more than 33,000 soldiers participating in another study, as well as insomnia reports from this cohort. They found that insomnia was linked to the occurrence of specific variants on chromosome 7.
More research is as always needed, but I think it is very likely that some young people have genetically determined biological systems which make it much harder for them to get sufficient sleep than others. This means some parents/caregivers also have a much harder job to help these young people get sufficient sleep. It’s not just a simple matter of “set bedtimes” and “no screens” and “routines” – yes, these things can help, but it’s a much more difficult challenge for some families than it is for others.
Finally, if you have worked really hard at supporting and encouraging your young person to get enough sleep, and are currently feeling despondent – remember the following:
Remember that sleep is only one factor influencing well-being. Yes, we know on average it matters, but that doesn’t mean it is a game changer for every young person. For some young people it may be that other factors are just as or much more important.
Managing sleep is a life long journey in my experience – with lots of bumps and curves in the road. There will be times our young people get less sleep than we would like. That’s okay – there will be periods of time they don’t eat well, exercise or get homework done either. We can always keep working on this as a goal and it doesn’t have to be perfect at all points during the journey.
Talk to your GP about your sleep concerns, or visit a psychologist to talk with them about what else you might be able to do. There are no easy fixes, but there are some therapies which have good evidence behind them.
If you’d like an article to show your child or teen about sleep, here is a link to one which might be helpful:
References
American Academy of Sleep Medicine. "Study links screen time to insomnia symptoms and depressive symptoms in adolescents: Regulating screen times may improve sleep health and reduce depression." ScienceDaily. ScienceDaily, 4 June 2018. www.sciencedaily.com/releases/2018/06/180604093124.htm
American Physiological Society. "More sleep may help teens with ADHD focus and organize: Study is first to find executive functioning skills deteriorate with lack of sleep." ScienceDaily. ScienceDaily, 8 April 2019. www.sciencedaily.com/releases/2019/04/190408081816.htm
Jack S Peltz, Ronald D Rogge, Heidi Connolly, Parents still matter: the influence of parental enforcement of bedtime on adolescents’ depressive symptoms, Sleep, , zsz287, https://doi.org/10.1093/sleep/zsz287
Jodi A. Mindell, Albert M. Li, Avi Sadeh, Robert Kwon, Daniel Y.T. Goh. Bedtime Routines for Young Children: A Dose-Dependent Association with Sleep Outcomes. SLEEP, 2015; DOI: 10.5665/sleep.4662
Max Hirshkowitz et al. National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health: Journal of the National Sleep Foundation, 2015 DOI: 10.1016/j.sleh.2014.12.010
Murray B. Stein, Michael J. McCarthy, Chia-Yen Chen, Sonia Jain, Joel Gelernter, Feng He, Steven G. Heeringa, Ronald C. Kessler, Matthew K. Nock, Stephan Ripke, Xiaoying Sun, Gary H. Wynn, Jordan W. Smoller, Robert J. Ursano. Genome-wide analysis of insomnia disorder. Molecular Psychiatry, 2018; DOI: 10.1038/s41380-018-0033-5
University of California - Berkeley. "Stressed to the max? Deep sleep can rewire the anxious brain: A sleepless night can trigger up to a 30 percent rise in emotional stress levels, new study shows." ScienceDaily. ScienceDaily, 4 November 2019. <www.sciencedaily.com/releases/2019/11/191104124140.htm>.
Wei Cheng, Edmund Rolls, Weikang Gong, Jingnan Du, Jie Zhang, Xiao-Yong Zhang, Fei Li, Jianfeng Feng. Sleep duration, brain structure, and psychiatric and cognitive problems in children. Molecular Psychiatry, 2020; DOI: 10.1038/s41380-020-0663-2
