Some driving-while-drowsy questions for your next sleep lecture

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A couple weeks ago we were walking our dogs past our neighbor’s house when we noticed that there was a smashed car parked out front. We asked our neighbor what happened. “My son fell asleep. He’s okay, and fortunately it was a single-car crash.”

For years I didn’t cover sleep in Intro Psych. And then a colleague’s teenage son fell asleep while driving, crossed the center line, and hit a semi head-on. He was killed instantly. The next time I taught Intro Psych, I covered sleep. And I have ever since.

The AAA Foundation for Traffic Safety has released their latest report, Acute Sleep Deprivation and Risk of Motor Vehicle Crash Involvement (2016).

Here are some clicker questions to get your students thinking about the scope of the problem driving while drowsy before launching into your coverage of sleep. (Answers are at the bottom.)

  1. What percentage “of U.S. adults usually sleep for less than 7 hours daily”?
    1. Less than 10%
    2. 10% to 20%
    3. 21% to 30 %
    4. 30% to 40%
  2. “[D]rivers who reported having slept for less than 4 hours in the past 24 hours had an estimated ________ times the odds of having contributed to the crash in which they were involved, compared with drivers who reported having slept for 7 or more hours in the past 24 hours.”
    1. 11.5
    2. 4.3
    3. 1.9
    4. 1.3
  3. What are the odds that someone with a blood alcohol concentration (BAC) level of 0.08 (legal limit in all U.S. states) will be in a crash as compared to someone with a BAC of 0.0?
    1. 6 to 7.8
    2. 3 to 6.5
    3. 0 to 5.2
    4. 7 to 3.9

The authors of this report acknowledge a number of limitations. “Possibly the most significant limitation of the study was that crashes that occurred between midnight and 6 AM” were not included in the dataset used in this study. Ask students to consider what impact including that data could have on the results. Interestingly, “drivers involved crashes in the first and last hours of data collection each day (i.e., 6:00 – 6:59 AM and 11:00 – 11:59 PM) reported having slept for an average of one full hour less in the past 24 hours than did drivers involved in crashes during the remainder of the day.”

For more research and recent statistics, check out the Governors Highway Safety Administration report, Wake Up Call! Understanding Drowsy Driving and What States Can Do (2016).


  1. D. 35% (That is “including 12% who report usually sleeping for 5 hours or less.”)
  2. A. 11.5. Drivers that slept between 4 and 5 hours were 4.3 times as likely to crash. Drivers that slept between 5 and 6 hours were 1.9 times as likely to crash. And drivers that slept between 6 and 7 hours were 1.3 times as likely to crash.
  3. D. 2.7 to 3.9. That’s approximately equivalent to sleeping between 4 and 5 hours. In other words, driving on less than 5 hours of sleep is about the same as driving with a BAC of 0.08.
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About the Author
Sue Frantz has taught psychology since 1992. She has served on several APA boards and committees, and was proud to serve the members of the Society for the Teaching of Psychology as their 2018 president. In 2013, she was the inaugural recipient of the APA award for Excellence in the Scholarship of Teaching and Learning at a Two-Year College or Campus. She received in 2016 the highest award for the teaching of psychology--the Charles L. Brewer Distinguished Teaching of Psychology Award. She presents nationally and internationally on the topics of educational technology and the pedagogy of psychology. She is co-author with Doug Bernstein and Steve Chew of Teaching Psychology: A Step-by-Step Guide, 3rd ed. and is co-author with Charles Stangor on Introduction to Psychology, 4.0.