Medical Mystery: Why is this teen so miserable?

Let me tell you about a young woman who came to me for a psychological evaluation and quietly cried throughout.

She was 16 and lovely in every way. Smart. Polite. Cared about school and earned good grades. On a varsity sports team. Well-liked by her friends. Treasured by her family. Adored by any grown-up who met her, including me.

As I said, lovely.

And she was absolutely miserable.

Christina, as I will call her here, couldn't say why she was so desperately unhappy, and this inability only seemed to make her cry more.

A series of diagnostic questions quickly established that she was anxious and depressed and that this had started, as it does for many, in her early teens.

As I explained to Christina and her parents, treatments for anxiety and depression include cognitive-behavior therapy (CBT) and SSRI medications such as Prozac or Zoloft.

But I was fairly certain that these measures might not work for her unless we could resolve a conflict far more nightmarish than getting her to come to therapy and take a daily pill.

So I asked her a question that isn't included on most psychological diagnostic interviews, but ought to be.

'What time do you go to bed on school nights?" I asked this young woman.

"Umm . . . 1:30?" came her response.

"And what time do you try to wake up for school in the mornings?"

"Uh . . . 6:30."

That's five hours of sleep. This is what I hear all the time from teenagers, but it still makes me cringe.

Because, you see, teens aren't just slightly shorter adults. Five hours of sleep isn't enough for anyone, but teenage brains are still developing in crucial ways and they need about 9 hours of sleep a night. Around the time they hit puberty, their brains begin to delay the secretion of melatonin-a hormone related to sleep onset-by two to three hours.

So, across the world, the teenage brain has physical difficulty falling asleep before 11 p.m. and a hard time waking itself up until around 8 a.m. This is a biological change that happens to just about all teenagers and explains why they - unlike grade school children - suddenly start going to bed later and become impossible to rouse in the morning.

Yet of all the grade levels, high school usually is assigned the earliest start times, when what teens really need is to sleep later.

In Christina's case, she had to wake up at 6:30 in order to make it to the bus for a school day that started at 7:50 am. She tried to make up for it by sleeping in on the weekends, which doesn't make up for lost sleep and can actually make the situation worse.

No amount of therapy or medication would change the fact that she was chronically sleep-deprived, I told Christina's parents.

"Remember what your sleep was like when she was a newborn?" I asked them. "Would any amount of therapy or antidepressants have made you less miserable or more able to function?"

The family quickly agreed to find any way possible to help Christina get to bed earlier and sleep later on weekdays. Given her busy schedule of sports and homework and life and her school's stubborn refusal to start any later than 7:50, I thought this would be impossible.

For most families, it would have been. But Christina and her family managed together to increase her sleep to about 8.5 hours on school nights. This involved (among many other things) parents being able to take her to school and the entire family turning off all electronics at 9 p.m.

Most important, Christina herself complied with the sleep rules in a way I've never seen a teenager manage.

We also added therapy and medication. And Christina got better.

But I wonder whether she would have done just as well if we had focused solely on increasing her sleep. Would this teen, and so many others like her, ever have become anxious and depressed if the school start-times we assigned allowed them enough sleep in the first place?

In 2014, the American Academy of Pediatrics declared that no middle or high school should start before 8:30 a.m. This was based on the overwhelming evidence of how sleep-deprived our teens are and how devastating the effects on their mental health, physical health, academic achievement, and simple ability to stay awake while driving a car.

But only about 15 percent of public high schools follow that medical advice. Is your teen's school one of them?

Katherine Dahlsgaard is lead psychologist of the Anxiety Behaviors Clinic at Children's Hospital of Philadelphia.