One of the things I love about writing a health-and-fitness column is reading what could be called out-of-the-blue research. For instance, who would've thought that yawning was a sign of anything other than fatigue or boredom?

But many now believe that the primary function of yawning is to increase alertness and better absorb information by cooling the brain.

Studies done in 2007 by Gordon Gallup at the State University of New York at Albany and his son Andrew at the University of Binghamton first suggested this. Further studies have supported their theory that the brain is similar to a computer in that it operates best when cool.

Yawning, it has been discovered, brings down body temperature.

That's why we yawn so often before we fall asleep and when we wake. These are the times, according to the research done by the Gallups, when body temperature is the highest.

One of the things I love best about my other job, teaching language arts to seventh graders, is that the summer vacation serves the same purpose as a yawn. The typical student in early September is far more alert and far better at absorbing information than in late May, and virtually every student I've encountered begins a new school year recharged and ready to learn.

Unfortunately, this feeling is sometimes gone I kid you not! by Thanksgiving vacation.

But I believe I know why. While part of it is that the routine and repetition of the school day produces a wane in motivation and indifference to success and subject matter, something else also produces a wane in motivation.

That something else is sleep deprivation.

Now the fact that many American adults are sleep deprived is well established. A 2008 survey by the U.S. Centers for Disease Control (CDC) of 20,000 adults, for example, found that in one month 10 percent of those polled did not have a single night where they got what they deemed "sufficient sleep." Nearly 40 percent said they started at least seven days in that month sleep deprived.

For teenagers during a typical month of the school year, you could expect those percentages to be even worse.

Why? Even more so than adults, studies have shown that teenagers are hardwired to be night owls.

As a result, most teens feel wide awake about the time they should be going to sleep if they're going to get the eight-to-10 hours of sleep research says that they need to function best and arrive to school on time. Additionally, the eight-to-10 hours of sleep teenagers need is up to three hours more than some adults require, according to a 2009 National Sleep Foundation study.

Moreover, late-night distractions have increased. Two generations ago, teenagers who couldn't or didn't want to go to sleep probably read, an act that is often in itself sleep-inducing.

Now, teens can be in their bedrooms quietly using the computer, playing video games (with headphones on or the sound off), or texting on a cell phone all of which have been shown to arouse rather than calm. So sleep for many teens gets delayed not only by the time spent doing these activities but also by the stimulation they produce.

And while some seventh graders tell me they avoid all these distractions and regularly get to bed before 10, far more report that they don't hit the sack until after midnight. As a result, some are so sleep deprived by the Thanksgiving vacation that there's a marked decrease in the depth of thought and the quality of work.

Yet there's still two-thirds of the school year remaining.

But short of creating a communal bedroom in the basement, what can parents do to help their teens get more sleep during the school year?

Although the first suggestion may create controversy in your community and cost it money, it needs to be discussed: lobby for a later secondary school start time to your school board.

Study after study has shown that elementary school children are better suited to do schoolwork at 7:30 a.m. than teenagers, yet Pennsylvania schools have junior and senior high schools begin near that time with the elementary schools starting between 60 to 90 minutes later. While having junior and senior highs begin at 9:30 a.m. the time often suggested as best and having the day end two hours later could cause insurmountable scheduling problems with transportation, sports, and student work schedules, there is a feasible alternative.

Start secondary school at 8:30 a.m. and shorten the length of the day by 30 minutes, primarily by reducing time between classes and "down time" time throughout the school day that's non-instructional.

The second suggestion that should make some students want to get more sleep will come next week but only after you read a bit more about the benefits to allowing teenagers to start school later.