Your teenager is right: Science says let them sleep later

Jessica Schladebeck

Next time you're trying to shake your teenager awake in spite of their groggy mumbles that they need more sleep, remember science says they're probably right.


It's recommended that teenagers and pre-teens get eight to 9½ hours of sleep, but recent studies done by both the National Sleep Foundation and Centers for Disease Control and Prevention show the majority of youngsters aren't hitting that requirement. Approximately 60 percent of students in grades six through eight and 87 percent of high schoolers are getting less than eight hours of sleep, and a quarter of those students are getting less than six.

The reason for the lack of sleep, at least in part, is the early start time for school days, said Dr. Elizabeth Imboden, a pediatrician at WellSpan’s York Pediatric Medicine practice.

"Kids just aren't naturally inclined to be awake at that time," she said.

Dr. Elizabeth Imboden

It has to do with their circadian rhythm — the biological clock that regulates periods of wakefulness and sleepiness.

"Once they hit those teenage years there's a shift, so their bodies don’t want to go to sleep as early as we think they should," Imboden said. "If you let these students listen to their bodies, they would probably go to sleep around 11."

Which means if they have to go to school before 8:30 a.m. — which is the recommended school start time by the CDC and the American Academy of Pediatricians — students aren't going to get the needed hours of sleep.

That's "battling against the internal clocks of teenagers," Imboden said. "We can’t say why the biology is that way; it's just the natural rhythm for a teenager."

York school starts: According to the CDC, five out of six middle and high schools across the country are in session before the recommended 8:30 start — a time that was developed by the CDC and Department of Education researchers after they reviewed data from a survey of 40,000 public school students following the 2011-12 school year.

The national average for school start times is 8:03 a.m., according to the CDC. However, the average start time for York County middle and high schools, based on the times listed in districts' student handbook, is 7:43 a.m. Spring Grove Area and South Eastern school districts have the earliest start times, with students coming in an hour earlier than what the science recommends.

Spring Grove Area High School has its students clocking in for homeroom at 7:25 a.m. and the district's middle school students are required to be in their desks two minutes later at 7:27 a.m, according to the student handbook. Also according to the handbooks, South Eastern Middle School students must be in class by 7:25 and the high-schoolers at Kennard-Dale must be in by 7:30 a.m.

Southwestern School district comes closest to the recommended start time, with its intermediate school coming in a few minutes after at 8:36 a.m. and high school students coming in at 8:25 a.m.

As it currently stands, school start times are determined either by district or individual schools; there is no state or federal guidelines regarding the start times of schools. In March 2015, the ZZZ's to A's Act was presented to a congressional committee, and if passed, would require the Secretary of Education to conduct a study determining the relationship between school start times and adolescent health, well-being and performance.

The effects: Students who are sleep-deprived are at risk for more than yawning through math class, Imboden said.

"Obviously they’re going to be sleepy," she said of those not getting their rest. "But there are studies that have shown not only a lack of focus throughout the day, but an increased rate of mood disorders — these students are more inclined to be depressed and anxious, and they tend to have worse grades."

Students who are tired in the morning are also less likely to eat breakfast, Imboden said, noting that a lack of fuel on top of too little sleep will further inhibit a students' ability to function. Sleep deprivation has also been linked to obesity.

"Hormones that help regulate the appetite are thought to be linked to how you use and get your energy," she said.

Sleep can also go a long way toward correcting hyper behavior.

"Some children who have sleep deficits ... hype themselves and become sort of hyperactive," she said, noting this form of overcompensating can lead guardians to think these students have ADHD or other behavioral syndromes. "I always consider their sleep habits when they're brought in for evaluation."

Change: Imboden said a study following Minneapolis Public School District changing the starting times of seven high schools from 7:15 a.m. to 8:40 a.m. showed benefits, including improvement in attendance and enrollment rates, increased daytime alertness and decreased student-reported depression.

While the science is highly in favor of a later school day, Imboden said there are a lot things — particularly the logistics like after school activity schedules and the teachers' willingness to change — that would make the shift difficult.

"Where schools have done it and made it work, they see it's in the best interest of the kids," she said. "It makes sense when things are done are certain way that it's hard to make those big changes. Hopefully as more information comes out — and if the academic and emotional concern for the kids comes first — we’ll start to see that change."

Until then, Imboden encourages parents to talk to their children about their sleep habits, especially if they're starting to feel down or under the weather.

Her patients "often come in with a complaint that can be tied into how they sleep," she said. "It’s kind of shocking when you ask them how many hours of sleep they get in a night."

— Reach Jessica Schaldebeck at