Stanford Medicine Newsletter Updates For the Local Community


From A's to Zzzz's

High cost of lost sleep in teens


Carolyn Walworth, 17, often reaches a breaking point around 11 pm, when she collapses in tears. For 10 minutes or so, she just sits and, overwhelmed by unrelenting school demands, cries at her desk. She is desperately tired and longs for sleep, but she knows that more homework assignments await her. She finally crawls into bed around midnight or later.

The next morning, she fights to stay awake in her first-period class, unable to focus on what’s being taught. “You feel tired and exhausted, but you think you just need to get through the day so you can go home and sleep,” said the Palo Alto teen.
Walworth is among a generation of teens growing up chronically sleep deprived. According to a 2006 National Sleep Foundation poll, more than 87 percent of U.S. high school students get far less than the recommended eight to 10 hours — a serious threat to their health, safety and academic success. Sleep deprivation increases the likelihood that teens will suffer myriad negative consequences, including an inability to concentrate, poor grades, driving incidents, anxiety, depression, thoughts of suicide and even suicide attempts.

“I think high school is the real danger spot in terms of sleep deprivation,” said William Dement, MD, PhD, founder of the Stanford Sleep Disorders Clinic at Stanford Medicine. “It’s a huge problem. What it means is that nobody performs at the level they could perform,” whether it’s in school, on the roadways, on the sports field or in terms of physical and emotional health.

Drains from both ends

Since the early ’90s, it’s been established that teens have a biological tendency to go to sleep later — by as much as two hours — than their younger counterparts. Yet when they enter their high school years, they find themselves at schools that typically start the day at an early hour. So their time for sleep is compressed, and many are jolted out of bed before they are physically or mentally ready. In the process, not only are they losing precious hours of rest, but their natural rhythm is disrupted.

They are being robbed of the rapid eye movement stage of sleep, some of the deepest, most productive sleep time, said Rafael Pelayo, MD, a pediatric sleep specialist with the Stanford Sleep Disorders Clinic. “When teens wake up earlier, it cuts off their dreams. We’re not giving them a chance to dream,” said Pelayo, a clinical professor of psychiatry and behavioral sciences at Stanford Medicine. “We’re sleep-depriving them.”

While teens are biologically programmed to stay up late, many social and cultural forces further limit their time for sleep. For one, the pressure to succeed is intense. In high-achieving communities like Palo Alto, that translates into students who are overwhelmed by additional homework for Advanced Placement classes, outside activities and, in some cases, part-time jobs, as well as peer, parental and community pressures to excel.

Mixed messages

At the same time, today’s teens are maturing in an era of ubiquitous electronic media, and they are fervent participants. Some 92 percent of U.S. teens have smartphones, and 24 percent say that they are online “constantly,” according to a 2015 report by the Pew Research Center. The problem is exacerbated when teens are exposed late at night to lighted screens, which send a message via the retina to the portion of the brain that controls the body’s circadian clock. The message: It’s not nighttime yet.

Illustration by Christopher Silas Neal


Nanci Yuan, MD, clinical associate professor of pediatrics at Lucile Packard Children’s Hospital Stanford and director of the Stanford Children’s Health Sleep Center, said she routinely sees young patients in her clinic who literally fall asleep at night with cellphone in hand.

“With academic demands and extracurricular activities, kids are going nonstop until they fall asleep exhausted at night. There is not an emphasis on the importance of sleep, as there is with nutrition and exercise,” she said.

Adolescents also are entering a period in which they are striving for autonomy and want to make their own, independent decisions, including when to go to sleep. But studies suggest that adolescents do better in terms of mood and fatigue levels if parents set the bedtime — and choose a time that is realistic for the child’s needs. According to one study in the journal Sleep, children are more likely to be depressed and to entertain thoughts of suicide if a parent sets a late bedtime of midnight or beyond.

Emotional toll

According to the national sleep poll, by the time U.S. students reach their senior year in high school, they are sleeping an average of 6.9 hours a night, down from an average of 8.4 hours in the sixth grade. Many studies show that students who sleep less suffer academically, as chronic sleep loss impairs the ability to remember, concentrate, think abstractly and solve problems.

“We hypothesize that when teens sleep, the brain is going through processes of consolidation or learning of experiences or memories,” Yuan said. “It’s like your brain is filtering itself while it’s sleeping — consolidating the important things and filtering out unimportant things.” When the brain is deprived of that opportunity, cognitive function suffers, along with the capacity to learn. “It impacts academic performance. It’s harder to take tests and answer questions if you are sleep deprived,” she said.

That’s why cramming, at the expense of sleep, is counterproductive, said Pelayo, who advises students not to lose sleep to study, or they’ll lose out in the end.

Research has shown that sleep problems among adolescents are a major risk factor for suicidal thoughts and death by suicide, which ranks as the third-leading cause of fatalities among 15-to-24-year-olds. This link between sleep and suicidal thoughts remains strong, independent of whether the teen is depressed or has drug and alcohol issues, according to some studies.

“Sleep, especially deep sleep, is like a balm for the brain,” said Shashank Joshi, MD, associate professor of psychiatry and behavioral sciences at Stanford Medicine. “The better your sleep, the more clearly you can think while awake, and it may enable you to seek help when a problem arises. Sleep deprivation can make it hard to remember what you need to do for your busy life. It takes away the support and the infrastructure.”

Sleep is believed to help regulate emotions and is an underlying component of many mood disorders, such as anxiety, depression and bipolar disorder. For students who are prone to these disorders, better sleep can help serve as a buffer and help prevent a downhill slide, said Joshi.

Changing school start times

Given the health risks associated with sleep problems, school districts around the country have been looking at one issue over which they have some control: school start times. Numerous studies have shown that in schools with later start times, students show significant improvement in mood and alertness, feel more empowered to succeed and are less likely to be involved in drowsy-driving incidents.

Bolstered by the evidence, the American Academy of Pediatrics in 2014 issued a strong policy statement encouraging middle and high school districts across the country to start school no earlier than 8:30 am. These decisions have been hugely contentious, as many consider school schedules sacrosanct and cite practical issues, such as bus schedules, as obstacles.

In Palo Alto, where a recent cluster of suicides has caused much communitywide soul-searching, the district superintendent issued a decision in the spring, over the objections of some teachers, students and administrators, to eliminate “zero period” for academic classes — an optional period that begins at 7:20 am that is generally offered for advanced studies.

But experts agree that it will take more than changes in school times to encourage teens to change their habits. More widespread education and resources for students, modified expectations on the parts of parents and teachers, and a cultural shift away from late-night electronic use are all needed to help youngsters gain much-needed rest.


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