It's a mantra from physicians, sleep experts and other health professionals we've come to expect: Teenagers are short on sleep. This lack of sleep contributes to a range of problems, including poor decision-making and reduced academic performance. As a result, widely accepted guidelines for teens include getting in nine hours of sleep per night.
A new study challenges these standard guidelines for how much sleep is optimal for teenagers, at least when it comes to academic performance. Researchers in the economics department at Brigham Young University found that teens perform better on standardized tests when they received seven hours of sleep per night. That's two hours less than the current federal guidelines, which recommend approximately nine hours of nightly sleep for adolescents.
BYU researchers analyzed the amount that teens slept on a nightly basis in relation to how the teens scored on standardized tests. They also examined how the relationship between sleep and test scores changed as teenagers grew older. They examined sleep habits and test scores of 1,724 students ages 10 to 19. Researchers took their data from a national survey conducted in 2002-2003, which collected information from children and families on a wide range of topics, including sleep, health and education.
What did they find? Teens scored highest on standardized tests when they had less sleep than federal guidelines recommend. They also found that teens needed less sleep with age to achieve their highest test scores. Optimal levels of sleep for teens were:
- Nine to 9.5 hours for 10-year-olds
- Eight to 8.5 hours for 12-year-olds
- Seven hours for 16-year-olds
For teens across the 10-19 age spectrum, sleeping less than or more than these optimal amounts was associated with lower test scores.
Before you go running off to re-set your teen's alarm clock, here are a couple of caveats to keep in mind when thinking about these results:
- First, we can't know from these results that sleep had an effect on students' test scores. The results of this study illustrate a relationship between sleep amounts and test achievement, and not a cause and effect.
- In addition, the data that the researchers relied upon came from self-reported accounts of sleep habits from children and their parents. This leaves open the likely possibility that in some -- if not many -- instances, teenagers' actual sleep habits were different than what they or their parents reported.
- Most important, and acknowledged by the researchers themselves, this study kept a narrow focus: to evaluate the amount that teens slept in relation to their performance on standardized tests. This research did not take into account any other aspects of teens' mental and physical health when determining "optimal" sleep.
When we open up this question to a broader and complete consideration of teens' sleep and their overall health, there is a great deal of evidence to suggest that seven hours of sleep may not be enough. I wrote about a large study of teen sleep and the health risks associated with not sleeping enough. In this study, researchers found that teens sleeping fewer than eight hours per night were significantly more likely to engage in several risky behaviors, including:
- Smoking cigarettes
- Smoking marijuana
- Not exercising regularly
- Spending more than three hours per day using a computer
- Suicidal thoughts
- Feelings of sadness and hopelessness
Of the 12,000 teens included in this study, 68.9 percent reported sleeping fewer than eight hours per night.
The National Sleep Foundation recommends that 8.5 to 9.25 hours of sleep a night is an appropriate and healthful amount of sleep for teens. In 2006, the NSF conducted a national poll on teens and their sleep habits. They found that only about 15 percent of teens were regularly getting 8.5 hours of sleep per night, the minimum end of their recommended range. They also found symptoms of depression and anxiety were most common among teens with sleep problems.
- 73 percent of teens who reported having difficulty with sleep also reported feelings of sadness, unhappiness and depression
- 58 percent reported excessive worrying
- 56 percent reported feelings of stress and anxiousness
In recent years there have been numerous studies that show the risks of sleep problems and low sleep among teens. There's evidence that indicates that sleep difficulties put teenagers at elevated risk for a range of mental and physical health problems, including:
The results of the study on teen sleep and test results are interesting and thought provoking. Among the things scientific inquiry does best is to challenge accepted truths and conventional wisdoms. This latest research is a great example of this, and raises questions worth further pursuit. At the same time, the stakes for our teens are high, in terms of their health and well-being. I'm not ready to change that teen-sleep mantra just yet.
Michael J. Breus, PhD
The Sleep Doctor™
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