How Many Hours of Sleep Should a 17-year Old Get?

Case Study: A mother of a 17-year old high-school senior contacted me . She was concerned that the young man wasn’t getting enough sleep. He played a sport every season, and got decent grades. He had friends and did not demonstrate any evidence of behavior or mood changes. The problem was that he appeared to sleep until the afternoon every Saturday. How many hours of sleep should a 17-year old get?

How many hours of sleep should a 17-year old get?

The answer to the question is fairly easy: it is 9 1/2 hours, according to most sleep experts. When I told this to the high schooler who is the subject of this case study, he gave a fairly typical reply:

“Ha. Ha-ha. Ha-HA-ha.”

I get that a lot.

The sarcasm, not meant to be rude, was his way of expressing that there was not a chance in hell he’d be able to get that much sleep. There simply were not enough hours in the day for him to get everything done and to sleep 9 1/2 hours!

Let’s call him “Nate”. A typical weekday ran as follows: Nate’s alarm would go off at 7:30 am. He’d take approximately 10 minutes to get out of bed and stumble to the bathroom. Breakfast for Nate consisted of a protein smoothie. He told me this had been his breakfast of choice for as long as he could remember. Nate never had been much of a big breakfast eater.

The most important meal of the day

That wasn’t a bad choice. I was glad to hear he got some protein in before school. Nate is 5 feet, 8 inches, 140 lbs. He’s a long-distance track athlete. Nate probably wouldn’t have made it to lunch block without something in his system.

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How many hours of sleep should a 17-year old get? Risk-taking requires rest!

Good diet is one of the three legs upon which all of health stands. The others are exercise and sleep(!). Some experts add stress reduction as a fourth leg.

Nate’s school is 1.1 miles from his home. He almost never walked or rode his bike. His mother drove him. This gave Nate a time cushion to help him get out of the house. Nate is lucky in this regard. Teenagers who need to catch a bus have tighter time constraints. If they miss the bus, they are sore out of luck, so they have to work harder at going out of the house.

If the teenager is old enough to drive, I hope they got enough sleep the night prior. It is well known that teen sleepiness is associated with accidents during the morning drive.

First block in Nate’s day starts at 8:30 am, one hour after he wakes up.

Nate Hits the Road

School lets out at 2:20 pm. Nate changes into running shorts and runs with his friends to track practice. He will not be home until 6:00 pm. Noah eats before showering, much to the chagrin of his mother and his younger brother. This particular issue is beyond the scope of our consult!

By the time Nate has eaten and showered, it is 7:oo pm and time for homework. The average high school student has 3.5 hours of homework per night. Nate is no different.

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How many hours of sleep should a 17-year old get? This kid may need a lot!

At 10:30 pm, homework done, Nate is finally able to text his girlfriend, which he will do for about one hour (or at least, that is how time he will admit to!)

Nate’s home is one where phones are permitted in the bedroom. Both Nate, his brother, and his mother, all keep their phones by the bedside. Here’s a possible area where I can intervene. Technology in the bedroom is associated with reduced sleep and increased daytime sleepiness in teens.

By my calculation, the maximum amount of sleep Nate would get in a typical night would be 8 hours, 1 1/2 hours less than the recommended amount. My suspicion is that the real number is probably closer to 7 1/2, given that Nate likes to watch YouTube videos and spends a fair amount of time on Facebook.

By the weekend, Nate has accumulated a sleep debt. Naturally, if he does not need to wake up for school, he will stay in bed. It is not unusual for Nate to wake up between 11:30 am and noon.

How many hours of sleep should a 17-year old get? The Fix

I had a number of suggestions for Nate.

For the average sleepy teenager, there are factors that cannot be changed, and a few that can. The start time for school should be later, but for now, 8:30 am remains too early for the average teen.

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How many hours of sleep should a 17-year old get? Girlfriend time is tough to negotiate

Sports are important to Nate, and I certainly would not recommend that he cut out track from his life. I have clients who play sports and participate in other after school activities as well. In these cases I recommend cutting out some activities. I call this “simplifying” the life of the teenager. Simplification is sometimes easier said than done.

Do homework during school hours

I asked Nate if he had a free block, formerly known as “study hall”. When I was in high school, very little studying got done in study hall. These days, over-scheduled students are taking advantage of study hall to get their homework done. It’s not possible for Nate to do all 3.5 hours of his homework during the 50 minute block, but it’s better than nothing. Nate admitted that it would be painful, but he could do the writing-intensive part of his homework during free block.

Bedrooms are for beds, not for phones

I also suggested that Nate’s family make a rule about technology in bedrooms. No intervention like this will work unless everyone else in the home is on board as well. There were no televisions in the bedrooms. This alone was a terrific start. The next step was to get everyone to agree to leave their devices in the kitchen, plugged in.

I left it to Nate and his mother to negotiate the time for plugging in the phone. I was a high school boy once. I know what this is like. I didn’t speak to my girlfriend nearly as often as kids these days do (I had to share the one land line we had with three sisters and my parents). But I probably would be texting her if I had a smart phone back then.

Get Back to Basics

It never hurts to make sure that you are eating well and getting plenty of exercise. By eating well, I mean something fairly specific:How many hours of sleep should a 17-year old get 5

  • Meat and vegetables
  • Nuts and seeds
  • Some fruit
  • Starches rarely
  • Sugar NEVER

Easier said than done, right? A growing body of evidence is supporting these basic guidelines.

Nate has already gotten the vigorous exercise part covered. If your child is not doing any exercise, I recommend they get out and move. It doesn’t really matter what they do as long as they do something regularly.

Now that you know how many hours of sleep should a 17-year old get, the last piece is convincing the school system. Later start times have been shown to show benefits and few down sides. If an effort to start school later is not underway in your district, I recommend getting one started!

And if you need a sleep coach, I can help!

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.

Need a SLEEP COACH?

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]

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

Need a SLEEP CONSULTANT?

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.

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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?