CDC: Less sleep, more risky behaviors

In the April 8, 2016 Weekly Morbidity and Mortality Weekly Report (MMWR), the Centers for Disease Control (CDC) studied data from 50,370 high school students in the Youth Behavior Risk Survey to evaluate the association between sleep duration on an average school night and five injury-related risk behaviors:

  1. Texting while driving
  2. Drinking and driving
  3. Riding with a driver who had been drinking
  4. Infrequent seatbelt use
  5. Infrequent bicycle helmet use

Adolescents are not getting enough sleep

First, they found that insufficient sleep is common amount high school students.

  • 6.3% of high school students report less than 4 hours of sleep on an average school night
  • 10.5% report 5 hours of sleep
  • 21.9% report 6 hours of sleep
  • 30.1% report 7 hours of sleep

In total, 69% of high school students report that they are getting 7 hours of sleep or less on an average school night. The National Sleep Foundation recommends that adolescents need 8-10 hours of sleep each night in order to support tremendous growth and development of their brains during puberty.

Duration of sleep on an average school night, grades 9-12 YRBS data, CDC

Overall, they found 31.2% of high school students are getting 8-10 hours of sleep, but a little less than 6% of all high school students are close to the average recommendation of 9.2 hours of sleep per night. They also found that 1.8% of high school students are sleeping 10 or more hours per night. However sleeping more than 10 hours per night is often associated with depression, and (as they study found) is linked to risky behaviors.

Texting while driving

High school students who slept 7 hours a night were 19% more likely  to report that they had been texting while driving during the past 30 days than those who slept 9 hours a night. The risk goes up with less and less sleep. The graph below shows, in blue, the percentage of teens getting the number of hours of sleep shown. In green, it shows the percentage of those who said that they were texting while driving in the last 30 days.  For students who were getting 9 hours of sleep, the incidence of texting while driving in the last 30 days was 20.9%. Those who were getting 7 hours or less were 19%-29% more likely to report driving while texting in the past 30 days.

Sleep duration and texting while driving, grades 9-12 YRBS data, CDC Sleep Duration and Injury-Related Risk Behaviors Among High School Students — United States, 2007–2013

Because more than 10 hours of sleep is often associated with depression, the risk actually increases for teens getting 10 or more hours of sleep each night (though only 1.8% of teens reported this amount of sleep).

Drinking and driving

High school students who slept 7 hours a night were 51% more likely to report that they had been drinking while driving during the past 30 days than those who slept 9 hours a night.  Those who slept 4 hours or less were over three times more likely to report driving while drinking in the last 30 days. The risk goes up with less and less sleep. The graph below shows, in blue, the percentage of teens getting the number of hours of sleep shown. In green, it shows the percentage of those who said that they were drinking while driving in the last 30 days. For students who were getting 9 hours of sleep, the incidence of drinking while driving in the last 30 days was 4.7%. Those who were getting 7 hours or less were 51%-314% more likely to report driving while drinking in the past 30 days.

Sleep duration and drinking while driving, grades 9-12 YRBS data, CDC Sleep Duration and Injury-Related Risk Behaviors Among High School Students — United States, 2007–2013

Because more than 10 hours of sleep is often associated with depression, the risk actually increases for teens getting 10 or more hours of sleep each night (though only 1.8% of teens reported this amount of sleep).

Riding with a driver who had been drinking

High school students who slept 7 hours a night were 20% more likely to report that during the past 30 days they had been riding with a driver who had been drinking than those who slept 9 hours a night.  The risk goes up with less and less sleep.  The graph below shows, in blue, the percentage of teens getting the number of hours of sleep shown. In green, it shows the percentage of those who said that they were riding with a driver who had been drinking.  For students who were getting 9 hours of sleep, the incidence of riding with a driver who had been drinking was 19.8%. Those who were getting 7 hours or less were 27%-84% more likely to report riding with a driver who had been drinking in the past 30 days.

Sleep duration and riding with a drinking driver , grades 9-12 YRBS data, CDC Sleep Duration and Injury-Related Risk Behaviors Among High School Students — United States, 2007–2013

Because more than 10 hours of sleep is often associated with depression, the risk actually increases for teens getting 10 or more hours of sleep each night (though only 1.8% of teens reported this amount of sleep).

Infrequent seatbelt use

High school students who slept 7 hours a night were 28% more likely to report that during the past 30 days they did not wear a seatbelt than those who slept 9 hours a night.  Those who slept 4 hours or less were over four times more likely to report driving not wearing a seatbelt in the last 30 days. The risk goes up with less and less sleep.  The graph below shows, in blue, the percentage of teens getting the number of hours of sleep shown. In green, it shows the percentage of those who said that they did not wear a seatbelt.   For students who were getting 9 hours of sleep, the incidence was 5.5%. Those who were getting 7 hours or less were 28%-450% more likely to report not wearing a seatbelt in past 30 days.

Sleep duration seatbelt use, grades 9-12 YRBS data, CDC Sleep Duration and Injury-Related Risk Behaviors Among High School Students — United States, 2007–2013

Because more than 10 hours of sleep is often associated with depression, the risk actually increases for teens getting 10 or more hours of sleep each night (though only 1.8% of teens reported this amount of sleep).

Infrequent bicycle helmet use

High school students who slept 7 hours a night were 6% more likely to report that during the past 30 days they did not wear a bicycle helmet than those who slept 9 hours a night.  The risk goes up with less and less sleep.  The graph below shows, in blue, the percentage of teens getting the number of hours of sleep shown. In green, it shows the percentage of those who said that they did not wear a bicycle helmet.  For students who were getting 9 hours of sleep, the incidence was 81.7%. Those who were getting 7 hours or less were 6%-12% more likely to report not wearing a helmet while riding a bicycle.

Sleep duration and bicycle helmet use, grades 9-12 YRBS data, CDC Sleep Duration and Injury-Related Risk Behaviors Among High School Students — United States, 2007–2013

Because more than 10 hours of sleep is often associated with depression, the risk actually increases for teens getting 10 or more hours of sleep each night (though only 1.8% of teens reported this amount of sleep).

Summary

In the summary for this report, the CDC writes:

What is already known about this topic? Insufficient sleep is common among high school students and is associated with an increased risk for unintentional injury from drowsy driving crashes and other causes.

What is added by this report? Students who reported sleeping ≤7 hours on school nights were more likely to report several injury-related risk behaviors (infrequent bicycle helmet use, infrequent seatbelt use, riding with a driver who had been drinking, drinking and driving, and texting while driving) compared with students who sleep 9 hours.

What are the implications for public health practice? High school faculty and administrators, as well as parents of high school students, should be made aware of the increased likelihood for risky behavioral choices among students who do not get enough sleep.