School Start Time: City Boys Matter!

Is a later school start time better for teenagers?

“Yes, of course”, you say! But how do you know that?

What if I told you that the correct answer is  “It depends”?

Does School Start Time Matter?

To answer this question, investigators at the National Institutes of Mental Health (NIMH) sent surveys to high school students, aged 13-17, all over the US. Almost 10,000 kids participated.

NIMH investigators asked questions about bedtimes, amount of sleep, and various other questions to tease out important demographic information. Weeknight bedtime was assessed with the question “What time do you usually go to bed on weeknights?” Sleep duration was assessed with the question “How many hours of sleep do you usually get on week (weekend) nights?” They asked this question to indicate whether the teenagers slept at least 8.5 hours of sleep. This number was chosen, instead of 9.5 hours, as is currently recommended, because at the time of the study, the National Sleep Foundation (NSF) recommended only 8.5 hours for teens.

Any high school kid will tell you that it’s much more complicated to understand the truth about their sleep. For this reason, the NIMH investigators asked about family characteristics, after-school jobs and extracurriculars. They also asked about school type (public vs. private, etc) and grade level.

Here’s What They Found

The NIMH school start time study is a good example of why it’s never a good idea to assume you know the answer to a question. Always investigate.

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The results were surprising. Investigators found some results they expected, but many others they did not expect.school start time 2

Teenagers Don’t Sleep Enough

The average number of weeknight sleep hours was 7.71 hours (7.60 for girls and 7.81 for boys). Not only was this result almost an hour less than the recommended NSF nightly allowance, it was almost two hours less than current recommendations!

But as this number was an average, it is obvious that some teenagers slept less than 7.71 hours, and some slept more. Extra sleep was associated with some surprising findings, which we’ll get to soon.

When school started later, students went to bed later. This was one of the expected findings.  And here is where it gets interesting.

School Start Time Matters… Until 8 AM

The investigators looked at school start times and then asked how many students got adequate sleep at each starting hour (e.g., 6:30 AM, 7:00 AM, etc.) When school started later, students got more sleep and more got the recommended amount of sleep (8.5 hours), but the effect went away for start times after 8:00 AM. In other words, if school started at 8:30 AM, or 9:00 AM, the students on average did not get more sleep! There appeared to be “diminishing returns”. In other words, later school start times was good for high schooler’s sleep… up to a point, namely 8:00 AM.

It Gets More Complicated…

It turns out that the benefits of later school start times may fall to boys only. When investigators looked at boys and girls separately, they found some unexpected results. School start time was not associated with hours of sleep for girls, regardless of start time. Similarly, later start times did not correlate with girls getting their 8.5 hours of sleep. School start time just didn’t seem to have anything to do at all with girl’s sleep. school start time 3

What about the boys? Since girls’ sleep didn’t seem to be affected by school start time, you would think that when you removed girls from the analysis that the effect would be even bigger for boys.

And it was… up to a point.

When school started later, boys got more sleep, and more boys got “adequate sleep” but the effect went away after 8AM.

City Boys vs. Country Boys

It turns out that location of the school mattered quite a bit. Investigators divided the kids into three groups: major metropolitan county (census-defined metropolitan counties with ≥ 1 million residents), other urbanized county (metropolitan counties with < 1 million residents), and non-urban county (non-metropolitan counties).

For boys living in major metropolitan areas, later start time was associated with adequate sleep, but only until 8 AM. For boys living in “other urbanized counties” and non-urban counties, start time had no effect on adequate sleep. Put another way, for boys going to big-city schools, later start times were associated with better sleep (up until 8 AM, of course…) For boys in smaller cities or suburbs, start time appeared to have no effect on quality sleep.school start time 4

Once again, girls sleep was unaffected by location. City girls got just as much sleep as country girls.

Make-up Sleep

In an earlier post, we showed that teenagers tend to sleep differently on weekends. These are the days we expect teenagers to “make-up” on sleep.

It is reasonable to guess that the teens who go to high schools with later start times might not need to make up for lost sleep on weekends. Indeed this is what the NIMH investigators found at first… until they “adjusted” the results. “Adjustment” means eliminating or reducing the confounding effects of extraneous confounding factors like sex, age, etc. The NIMH investigators adjusted data for all their results in this study, but when they used adjustment to look at make-up sleep, they got an unexpected result:

There seemed to be a correlation between later start times and less make-up sleep, but the effect would go away after normalizing for age, sex, school level, and school location (city vs. country, etc). In other words, overall later school start time did not give teenagers the opportunity to make up for lost sleep.

Strengths of the Study

Large studies are always better than small studies. The statistics always get better for one thing. Put another way, you can resolve small differences, and bring out subtleties better if your study has more subjects. We believe something closer to the truth is found when you look at very large populations. Almost 10,000 high school kids is a large enough sample size to give results we can believe. And indeed this study found some interesting differences: between boys and girls, and between city boys and country boys.school start time 5

The large sample size also allowed the NIMH investigators to uncover the compelling finding about the hour of 8:00 AM: Later start times did indeed matter, but the effect would disappear after 8.

Limitations of the Study

Survey results are never the best way to arrive at the truth. Think of those times in American history when opinion polls grossly mis-calculate the outcomes of elections! The NIMH school start time study was limited by use of a cross-sectional survey as the research tool. As a result, all the investigators could tell us is that there were associations between things like school start times and hours of sleep. They were unable to tell us if any two things were causally related to each other.

Furthermore, it’s far more accurate to measure hours of sleep than it is to ask a teenager how long she slept! In a study this large, actual measurement was not possible. They also did not ask the kids about confounders like cell phone use, which may vary from group to group.

Finally, there is the question of generalizability. It is important, when reading about studies like this on the internet, to ask an important question: “Does this study apply to me?”  If this same study were performed on teenagers living in isolated villages deep in the Amazon River basin, you might justifiably say “I’m not sure this study tells me anything about my teenager’s sleep”. But you can still ask the question about studies done on American teenagers. Look carefully at the study and ask yourself how easily your child could have been one of the kids who turned in a survey.

Summary: The NIMH School Start Time Study Suggests…

  • That teenagers don’t get enough sleep
  • That later start times matter, but
    • only if you’re a boy, and
    • only if you live in a big city
    • only until 8 AM

What they’re saying about Sleep, Baby!

[testimonials]

Why Does My Teen Sleep So Much?

Why does Jackie sleep so much?

As Jackie’s mother was asking the question, I was already suspecting that Jackie actually didn’t sleep enough!

They Sleep So Much, and Yet So Little!

Jackie (not her real name) is a pretty typical high-school sophomore. She’s a good student. She plays three sports. When I met her she was running track in the fall. The problem, Jackie told me, was that she needed to do homework, but she couldn’t keep her eyes open during dinner. She was afraid that her grades were going to suffer if she couldn’t complete her school work.

She would wake up at 6:30 in the morning. Or rather, Jackie’s mother would wake her up at 7. There’s no way Jackie would wake up on her own. On Saturdays and Sundays, the girl would wake up at 10.

The school day would go fine. Jackie didn’t report any sleeping or even drowsiness during the day. Immediately after school she’d go to track practice, four days per week. She’d compete once per week. After track, Jackie would come home, eat dinner and do homework. Most nights Jackie wouldn’t get to bed until after 11 PM.

Lately the fatigue was catching up to Jackie. By dinner time she was wiped out. That’s when they sought my advice.

The Story

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Do I sleep so much?

I took a complete history from Jackie and her mother. She was healthy (no snoring, no asthma), had no emotional or drug problems (that she would admit to). There was no television in her room. The rule in house was that no cell phones or tablets were allowed in the bedroom. Jackie’s parents kept to this rule as well. She had been a good sleeper up to this point. There was no family history of parasomnia.

The answers to these and other questions led me to believe that the reason for Jackie’s sleepiness after school was not a result of any health or emotional problem. Jackie would sleep so much after school because she wasn’t sleeping enough at night.

Teens Don’t Sleep So Much

Teenagers are supposed to get 9 1/2 hours of sleep every night. But on average, teens get 7- 7 1/2 hours. In addition, the teen sleep cycle is delayed compared to their younger peers. The teenage sleep cycle is such that they will tend to want to fall asleep at 11 PM, but they’ll need to wake up at 8:30 AM in order to get their 9 1/2 hours. Jackie was already in school when her brain wanted her to be waking up!

As a result, Jackie was genuinely exhausted by the time track practice was over. Her mother had wondered if Jackie needed to quit track so that she could get her homework done earlier.

Sports are Good for Kids

I explained that the issue was not track, it was the early wake-up time required by Jackie’s school. Jackie was glad to hear this. She really enjoyed track. She enjoyed the competition, and several of her good friends were on the team.

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In fact, vigorous exercise is good for teens (as it is for all of us!) I suspect that if Jackie wasn’t running track she probably would not be doing as well as she was. Teens who participate in sports tend to be more organized than their non-athletic peers, not least because sports schedules force the young person to be more efficient with study and homework.

The Fix for Jackie

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If I’m going to sleep so much, I’m going to do it by the lake

Jackie’s situation is far from unique. High school administrators are well aware of sleep issues among the student body. With so many students involved in after-school activities, the sleep-deprivation problem is made worse. To respond to the problem, many schools have devised an ingenious solution: the study hall.

Study hall of course is an old concept. But these days schools are permitting extra study hall periods dedicated to homework.

There are several advantages to the student who is permitted to get homework done during school hours. Not least, student-athletes like Jackie can return from practice, shower, eat dinner, and go to sleep!

The solution is not ideal, however. The best solution would be to start school later for high schoolers. Such solutions in fact have been tried in several school districts, with positive results.

Jackie’s guidance counselor was enormously helpful. With her help, Jackie was able to schedule two extra study hall periods per week, which were enough to allow Jackie to finish all her homework before track practices and meets.

The take-home lesson for parents is that your teen isn’t sleeping as much as you think. In fact, they probably aren’t sleeping enough. I recommend trying to figure out how much sleep your teen is getting at night. Chances are very good that she is not getting 9 1/2 hours. If daytime sleepiness is becoming a problem, then some kind of intervention would help you.

That’s where I come in. I help parents solve their teenagers’ sleep problems. If you are dealing with a sleepy teenager, who nods out during school, or upon returning home, I can help.

Teens Don’t Sleep Enough. It’s YOUR FAULT

We all know that teens don’t sleep enough. Why don’t they?

Parents, you aren’t going to like the reason: it’s your fault.

 

Why Teens Don’t Sleep Enough

 

The National Sleep Foundation (NSF) performs an annual poll to learn more about the way Americans sleep. In 2014, the poll focused on parental attitudes toward their children’s sleep. In particular NSF asked parents how much they valued sleep and how much sleep they believe their children actually got.

Then NSF asked a series of questions about household rules regarding sleep, including questions about limits setting on caffeine and use of technology in the bedroom.

Parents were asked to fill out a survey on the internet. Questions were asked about demographics (age, socioeconomic status, etc), followed by questions about sleep.

The Results

Most parents (>90%) reported that sleep was either “very important” or “extremely important” for good mood, health, and performance in both themselves and their children.

teens don't sleep enough
Teens don’t sleep enough and neither do their younger sibs

However, almost 90% children did not in fact sleep the recommended number of hours, whether they were younger children or adolescents. The children in the study reportedly sleep fewer hours than children in other comparable developed countries.

Children 6-11 years of age ideally should get about 10 hours sleep. Teenagers should get 9 1/2 hours. In the NSF study, both groups got about one full hour less sleep than recommended.

Adolescents (12-17 years old) slept fewer hours than their younger siblings during the week. However, on weekends, both groups slept the same number of hours.

The survey was concerned not only with quantity of sleep, but also with quality. Slightly less than half of parents thought the quality of their children’s sleep was “excellent” or “good”.

Limits Setting and Enforcement

The survey was particularly interested in rules setting and enforcement, and the effect of rules on sleep. The results were significant.

Long hours of sleep were significantly associated with parents being married, always enforcing rules about how late the child can consume caffeine, and never leaving any technology on in the bedroom. Excellent sleep quality was significantly associated with always enforcing a bedtime for the child and with never leaving any technology on in the bedroom.

Not surprisingly, if parents slept with electronic devices, so did their children. Many parents admitted on the survey that they would read and respond to text messages after they had planned to go to sleep!

“Technology” was defined as virtually any electronic device with a screen, including television. In the age of the cell phone, the television continues to be the biggest contributor to loss of sleep.

TV is a Bad Actor

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Teens don’t sleep enough if they watch the big flat screen before bed

The study did try to explain why television appears to be worse than cell phones for inhibiting sleep. We can make some guesses, however.

It is well known that the blue light emitted from screens is bad for sleep. Exposure to this light tends to delay the sleep cycle and to increase the amount of time it takes to fall asleep (“sleep latency”). Television screens are larger than cell phones or tablets. In fact, on average television screens are larger than they have ever been! It’s possible that the larger the screen, the larger the amount of blue light. As a result, sleep is even more inhibited.

Conclusions

Like it or not, parents are role models for their children. It’s not reasonable to hold your kids to a standard that you yourself cannot keep up. If you have a television in your bedroom, how can you deny one to your child? If you sleep with your cell phone or tablet on your end table, your child is going to find out.

teens don't sleep enough 4
Teens don’t sleep enough after an espresso

The parents who sleep the best, and who have children who sleep the best, make rules about technology use, enforce those rules, and observe the rules themselves!

 

Removing technology from the bedroom is easy, or should be. More difficult is modeling behavior for your children around healthy bed times. The NSF study showed that parents who get enough sleep quantity and quality have children who also sleep long and well.

Caffeine use is an important contributor to sleep hygiene, but it’s not often discussed. This study does us a favor by raising the issue of caffeine consumption in both parents and children.

As an admitted caffeine addict, I appreciate that the issue is being raised and I’m grateful to the NSF for bringing it up. I’m also grateful that my children have not inherited my addiction. But perhaps we’re not merely lucky. We make a conscious effort to model healthy eating and drinking behavior for our children. The same goes for exercise.

My own parents were heroic coffee drinkers and neither lifted a finger of exercise. How my sisters and I ever became health nuts will remain a mystery. Perhaps our parents modeled better behavior than I give them credit for.

Most children today are not so lucky. Parental modeling of behavior matters.

When I counsel a family about a sleep problem, I’m really counseling the entire family. To me the expression “sleep hygiene” refers to the sleep habits of the entire family, not just a child’s.

The truth is, fixing a child’s sleep problem often means fixing the entire family’s sleep problem. If you want to find out more, feel free to contact me. I can help.

Cell Phones Cause Sleep Problems in Teens

Every year since 2002, the National Sleep Foundation conducts a “Sleep in America” poll. The topics vary every year. In 2011, NSF focused exclusively on the things we do in our bedrooms (you know, besides sleep).  Data from that poll continue to generate insights into how we sleep, or don’t sleep as the case may be. In 2016, investigators pulled data from the “Bedroom Poll”, looking at adolescent technology use and how it affected their sleep. The result? Cell phones cause sleep problems.

The Study

This study looked at data from 259 kids aged 13-21 years. Investigators asked the teens when they went to bed and how long they slept. They were particularly interested in the kids’ own assessment of how tired they were during the day, and whether they believed they were getting “adequate” amounts of sleep at night. Finally, all these data were compared to the amount of time the teens spent doing things on their phones.

cell phones cause sleep problems 1

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The Results

The respondents slept an average of 7.3 ± 1.3 hours. The recommended amount of sleep, according to Nationwide Children’s Hospital, is 9 1/2 hours.

An astoundingly large number of respondents (97%) used some kind of technology before bed. Increased technology use and the frequency of the cell phone waking you up correlated with waking too early, waking unrefreshed, and daytime sleepiness. Teens who said their sleep was “inadequate” had shorter sleep duration, greater  technology use before bedtime, feeling unrefreshed on waking, and greater daytime sleepiness than teens reporting “adequate” sleep.

The Conclusion: Cell phones cause sleep problems for teens

I can hear parents of of teenagers reading this thinking to themselves “tell me something I don’t know!” But scientific studies like these, even though they rely on survey data, are important because they give us an idea of the magnitude of the problem.

cell phones cause sleep problems 3
Cell phones cause sleep problems? Or sleep problems cause cell phone use?

In this survey, the average teenager got 2 hours less sleep than the recommended 9 1/2 hours. I told my own teenagers about this result and they it surprised them. They guessed the reported number of hours would be less than 7 hours. I reminded them that this was the number the kids reported to adults administering a survey. The real number of hours of sleep may in fact be lower.

Which came first?

Another problem with the study is that it only describes the kids report. The study shows a correlation between cell phone use and bad sleep. It doesn’t tell us anything about causation. In other words, do cell phones cause sleep problems? Or do sleep problems cause kids to stay up and use their phones?

To answer questions like this, we need to perform a controlled trial. We would take this same group of kids and randomly divide them into two groups. One group would keep their cell phones in their bedrooms as they usually do. The other group would leave the phone in another room. At the end of some period of time, say 3 months, we’d ask the kids again about quantity and quality of their sleep.

How do you think a study like this would turn out?

Kleine-Levin Syndrome: A Reduced Understanding

In 1925, Frankfurt Neurologist Willi Kleine published a paper he titled “Periodische Schlafsucht” (periodic sleepiness). In his paper, Kleine described 5 patients who mysteriously slept for abnormally long periods. Neither Kleine nor his colleagues could explain the cause of the sleepiness. Four years later, New York psychiatrist Max Levin, studying narcolepsy, came across a young man who both slept and ate too much. He collected five more such cases, one of whom happened to be one of Kleine’s patients. Dr.  Macdonald Critchley described the strange condition in even more detail, and named it Kleine-Levin Syndrome.

Understanding Kleine-Levin Syndrome

In the days before the internet, doctors spent a lot of time in libraries. They scanned thousands of pages of old medical journals, often written in languages they did not speak. One such search turned up a case of a teenage girl who appeared to have Kleine-Levin Syndrome. This occurred in France in the late 18th century:

‘In her fourteenth year, she was overcome with a lethargic sleep which lasted several days; and it was so profound that she was believed dead. From that point forward, the affection of sleep recurred at irregular intervals; it usually lasted eight to ten days, continuing at times for fifteen; and upon one sole occasion, it persisted into the seventeenth day … During the first four years of her disease, this poor girl had appetites as bizarre as they were dangerous, causing her to eat lime, plaster, soil, and vinegar. Thereafter, these appetites subsided, and she nourished herself indiscriminately with all sorts of aliment, excepting bread, for which she maintained an insuperable loathing till she was perfectly cured. This food always occasioned vomiting.’

Later…

Over time, investigators gathered more cases. They were then able to sketch the strange disease in more detail.

  • Over 70% of the victims were teenage boys.
  • Patients would sleep up to 22 hours per day.
  • Episodes of sleepiness would last about 10 days, and would recur every 3-4 months.
  • Odd compulsive eating behaviors are common, as is bizarre sexual behavior.
  • The illness would last about 8 years and then vanish as mysteriously as it appeared.
  • Over half the cases follow a viral infection
kleine-levin syndrome 3
Nice Fairy Tale. Scary Disease

In the 20th century, though most of the sufferers of Kleine-Levin Syndrome were adolescent boys, the disease began to be called “Sleeping Beauty Syndrome”. The real illness has nothing of a fairy tale quality to it, however.


The Kleine-Levin Syndrome Foundation gives an unusual description of the effect the disease has on the minds of its victims. In addition to the sleepiness and excessive hunger, KLSF describes sufferers as having “a reduced understanding of the world.”

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A Reduced Understanding of the World

It’s a description that’s both frightening and arresting. What does KLSF mean by “a reduced understanding of the world”?

During episodes, these young people display confusion and apathy. They appear withdrawn (in the few hours per day they were awake). Then there is the bizarre hunger and hyper-sexuality.

All we can say about the cause of Kleine-Levin Syndrome is that it appears to be a brain disease. It may have a viral trigger. KLS may represent an autoimmune disease. Because it is so rare (1 case per 1 million population), KLS is difficult to study.

Treatment

There is no specific treatment for KLS. The best doctors and the victim’s family can do is support them. There is some suggestion that the drug Lithium can reduce the number of episodes. With time, the symptoms disappear and the young person resumes his life. He’s lost a huge chunk of his young life, but he emerges without apparent long-term consequences.kleine-levin syndrome 2

As frightening and as devastating as KLS is for the sufferer and his family, the disease resolves and never comes back. This is an important difference between KLS and Narcolepsy, which can last a lifetime.

 

How Puberty Affects Sleep

The changes that happen during puberty go way beyond the bodily transformations we all know about. The adolescent brain changes too. And brain changes relate to sleep changes. How puberty affects sleep has little to do with how late the teenager stays up. It has more to do with changes that are happening in her brain.

How Puberty Affects Sleep is Deeper Than Skin

No, teens are not moodier because they are not sleeping well. And they’re not sleeping more because they are moody. The moodiness and the changes in sleep are separate by-products of puberty. The sleepiness, however, is made worse by the unfortunate timing of school hours, a subject we will get to.

We many not remember our own sleep patterns during our teen years. But we probably started going to bed later and wake up later as well. Those of us who have teenagers, or who know one well, may have noticed this. It seems fairly universal.

We may have also noticed that the teen may be very unhappy indeed about having to wake up early for school. Many teens report being wiped out after school, especially if they play sports. It’s tempting to blame the teenager for staying up to late and causing her own sleepiness. But if you yield to that temptation you are only half-right: part of the staying up late is cultural. But part of it is biological.

Nature and Nurture

For a long time, the question simply had not been studied. Teenagers tended to stay up later. We assumed we did this because, well, they are teenagers. But since the 1990’s there have been a number of studies of how puberty affects sleep in large groups of teenagers.

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How puberty affects sleep?

For example, Mary Carskadon and her colleagues at Brown University in Rhode Island, USA, did a study of fourth to sixth graders in public school and came up with some interesting findings. They found that later bedtimes and pubertal stage were closely related to one another. In other words, as the children went through puberty, they simply went to bed later, even after controlling for age, birth order, and other factors.

Laberge, et al, in a study of Quebecois teenagers, also found that adolescents were going to bed later. The investigators also found that these kids were sleeping less, most likely because of having to wake up for school. In fact the study showed that teenagers “slept in” on weekends when there was no school. “You need a study to tell me my kids sleeps late on Saturday morning?” you may ask. Sometimes you do.

Israeli Teens Do it Too

A two-year study out of Tel Aviv followed kids as they passed through puberty and measured their sleep. They found that teen sleep-wake patterns reorganize during puberty. Just as with the Rhode Island and Quebec study, the Israeli study showed later bedtimes, less overall sleep, and increased daytime sleepiness. Investigators also looked at tolerance for sleep deprivation and found that the teenagers actually tolerate the loss of sleep better than younger children do.

Here we have three studies from different parts of the world which come up with remarkably similar results. Is there something to this relationship between puberty and sleep?

What if It’s True?

If these studies reflect real changes in the sleep-wake patterns of teenagers, so what? Is it only an interesting discovery that teaches us something about puberty we didn’t know before?how puberty affects sleep 3

No. It’s it’s not just interesting, it’s important. Later sleep times in puberty are often a bad fit for the school schedule that we impose on teenagers. Teens already stay up later for a variety of reasons, some of which relate to 21st century culture. Now that we know that the sleep-wake cycle shifts later in the day for teens, we ought to consider how we can better help them get through the day without getting exhausted.

This is where a sleep consultant can help you. If you have a teen and you’re struggling with a sleep problem, I can help. Please feel free to contact me.