Since the late ’80s, we have known that teens’ body clocks shift later. In other words, they begin to get sleepy later at night. The shift starts early in puberty, usually around 10 years old, and continues into the early 20s. This in and of itself isn’t a problem.

But according to a 2014 study by the CDC, 93% of U.S. high schools and 83% of middle schools start before 8:30 a.m. Now we have a problem.

The American Academy of Sleep Medicine recommends that teens should sleep 8-10 hours nightly. Between the biological shift towards later bedtimes and the early school start times, most American teens are falling woefully short of this.

According to internal data from sleep tracking app Sleep Cycle, which looked at the sleeping habits of around 100,000 American teens for the 2016-2017 and 2017-2018 school year, teens log an average of 7:14 minutes on school nights, going to bed around 11:45 p.m. and waking at 7:04 a.m. (On the weekends they’re getting to bed later — around 12:30 a.m. — but they’re also sleeping in past 8:30 a.m., bringing the average up to about 8 hours).

How bad is this for our teens? Very, very bad.

According to the CDC, teens who do not get enough sleep are more likely to be overweight, not get enough exercise, suffer from depression, get bad grades, and engage in unhealthy risk behaviors like drinking, smoking, and drug use.

There is also a correlation between lack of sleep and mood problems, including suicidality.

It is one area of research where the results are conclusive: there is an enormous body of research showing that later school start times have positive outcomes; there are no studies that show students do better with an earlier schedule.

And yet it is staggering how slowly the research knowledge has translated into public policy on this issue.

I’m not the first parent – or expert – to sound this alarm.

In 2011, the great national nonprofit Start School Later was founded, which now has chapters in many states around the country. I was one of the three main leaders of the Seattle chapter and, in 2016, we got the school district to change to later school start times. Just in the last couple of months a study was released showing the impact of that change.

They were exactly what we expected.

We moved from start times of 7:50 a.m. for middle and high school to 8:45 a.m. – 55 minutes later. The students ended up getting 34 minutes more sleep on average, increasing their nightly total from 6 hours and 50 minutes to 7 hours and 24 minutes. They also found a reduction in tardiness and absences and improvements in grades.

So how can you support your teen?

For one thing, please don’t fall for the myth that your teens can make up for lost sleep on the weekends. The research doesn’t at all support this idea. As a colleague of mine says, you would never feed your teen two-thirds of the food that they need Monday through Friday and then just let them eat as much as they need to on the weekends.

Trying to establish good sleep hygiene is also important, which can include things like keeping screens and smartphones out of the bedroom and limiting screen time before bed.

If your teen is struggling with severe mood problems, get an expert involved. Don’t wait until it reaches crisis. One of the things that I’ve seen several times in my clinic are teenage patients who come in who have been suicidal; some have even made attempts. They come in sleep deprived, depressed; their shoulders are hunched, they’re not looking at me. They let their parent do most of the talking in the first appointment. Then in subsequent appointments, as we work to improve their sleep, they’re standing tall; they can look me in the eyes; they can speak for themselves.

Parents have often said to me afterward that they wished they had worked on their kid’s sleep sooner. It’s heartbreaking. It’s such a traumatic experience for a young person and part of the solution may be as simple as a good night’s sleep.

But the most important thing you can do – and I can’t stress this enough – is to get involved in the push for later school start times. Start School Later is an excellent resource for that.

Our job as parents is to keep the focus on how can we set our system up to promote teen health and optimal learning, and set up systems so that our teenagers can thrive.