Teen Car Accidents: School Start Time Matters

The two age groups most at risk for getting into car accidents are teenagers and the elderly. The reasons for the high accident rate in each group are obviously different. Elderly people’s faculties tend not to be as sharp as they once were. Reaction time slows. Eyesight and hearing decline. The causes of teen car accidents are completely different. Besides lack of experience, there is risk-taking behavior and poor judgment. But one factor in the high rate of teen car accidents is getting more attention in recent years: sleepiness. It is well known that early high school start times make for sleepier teenagers. Now there is a growing body of scientific literature that is suggesting a link between school start time and car accidents.

What Does School Start Time Have to Do With Teen Car Accidents?

In 1998, University of Kentucky researchers Fred Danner and Barbara Phillips got word that a single county in their state planned to increase high school start time. In 1998, schools in the county started at 7:30 am. In 1999 start time was moved to 8:30 am. The remainder of the state kept the same start time. Danner and Phillips seized on this opportunity to test whether the change in start time would have any effect effect on the rate of teen car accidents.

Danner and Phillips found that high schoolers in all four years got substantially more sleep in 1999 than in 1998. The number of students getting the recommended amount of sleep, 9+ hours, increased from 6.3% to 10.8%. The number of students getting at least 8 hours increased from about one-third to over 50%.

But the most interesting finding was the drop in the rate in teen car accidents.

Despite rapid population growth, with many more cars on the road, the rate of crashes in the study county dropped after the change in school start time. The average crash rates in the 2 years after the change in school start times dropped 16.5% in the study county.  At the same time, the car accident rate increased 7.8% in the rest of the state.


Danner and Phillips were careful not to conclude that the school start time directly caused fewer accidents. The study hampered by the unforeseen circumstance that the student ID numbering system changed between 1998 and 1999. As a result, the investigators could not go back and find out if particular teens involved in accidents were sleeping more or less.

The Virginia High School Start Time Study

One study alone cannot answer a question. This is especially so when the study only shows a correlation (as opposed to a causal relationship) between teen sleep and car accidents. Any scientific question is best answered by several studies looking at the same problem. In 2011, a group of researchers at Eastern Virginia Medical School published a study similar to the 2008 Danner and Phillips study.teen car accidents 2

The Virginia investigators compared teen driver accident rates in two neighboring counties with different high school start times. The Virginia Beach district started high school 75-80 minutes earlier than the neighboring Chesapeake district. The investigators guessed that the rate of teen car accidents would be higher in  Virginia Beach than in Chesapeake.

This is indeed what they found.

For Virginia Beach and Chesapeake, teen drivers’ crash rates in 2008 were 65.8/1000 and 46.6/1000, respectively. In 2007 were 71.2/1000 and 55.6/1000. Teen drivers accident peaks in the morning occurred one hour earlier in Virginia Beach than in Chesapeake, consistent with school commute time. Congestion data for the two towns did not explain the different accident rates.

The Australian Teen Car Accidents Study

This study, published in 2013, was the first study of teen car accidents that was prospective as opposed to retrospective. That is, a large group of young people (over 19,000!) was signed up to participate. They were then followed over a number of years, while carefully documenting hours of sleep and other important contributing factors.

Here’s what they found: On average, teens who reported sleeping 6 or fewer hours per night had an increased risk for accidents compared with those who slept more than 6 hours. If the teen slept less on weekends, they were more likely to be involved in “run-off-road” accidents. Peak hours for these accidents occurred between 8 pm and 6 am. teen car accidents 3

Whereas the study did not address school start times as such, it offers some very strong data to the body of literature. First, it was a very large study. It also controlled for various factors that could skew the results of a smaller studies. As the evidence grows stronger that sleepiness leads to car crashes, the case for later school start times becomes stronger as well.

Back to Virginia

Finally we look at a second study published in 2014 by the Eastern Virginia Medical School group. This time, the investigators compared data for teen car accidents in two neighboring counties in central Virginia. Henrico County schools began at 8:45 am and Chesterfield County schools began at 7:20 am.  This time, investigators not only compared the rate of teen car accidents in each county, they also compared the rates of adult accidents as a comparison group.

For 2009-2010, Chesterfield teens had a higher accident rate than the later starting Henrico teens. There was no such difference in adult crash rates for either year in Henrico County and Chesterfield County, making it less likely that a systemic (not teen-specific) difference between the two counties was to blame for the difference.

Investigators also found two peak hours for teen car accidents, one in the morning when teens drive to school, and another in the afternoon when sleep deprivation begins to kick in.

Putting It All Together

One study never answers an important scientific question. The more studies that look at a question, the more likely we are to come up with an answer that approaches the truth. As the body of evidence grows, we are beginning to see a picture emerging that describes the dangers of early school start time for high schoolers. It seems that teens who must get up earlier than they should are more dangerous on the road.

There is an easy fix for this one. Start school later. There are a number of objections to this concept that deserve attention. Indeed attention has been paid to these objections. We will address them in future posts.

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.

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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.


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.

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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.

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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.

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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?

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.’


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
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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.”


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.


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.