Every morning the bell rings at 8:10 a.m. at Smiths Falls District Collegiate Institute, and herds of weary high-school students stumble into class like zombies.

"We're always tired," Grade 10 student Michelle Norlock says. "It's hard, because you're not focusing and you can't really understand what the teacher is saying."

"My first class, I just want to fall asleep and not really pay attention, because I'm exhausted from the night before," echoes Grade 9 student Angelina Holmes.

Parents of any era know it's often a struggle to coax a groggy teenager out of bed. But two Grade 10 students at SFDCI in Smiths Falls, Ont., wondered if their peers are, in fact, chronically sleep deprived.

Elizabeth Horsey and Quin Atkinson asked more than 300 students about their sleeping habits for a recent science fair project. Their questions included a survey known as the Epworth Sleepiness Scale that's commonly used to detect sleep disorders.

It’s recommended that 13- to 18-year-olds get eight to 10 hours of sleep per night, according to the Canadian Paediatric Society. Studies suggest more than half of Canadian teens get less than that. (Duncan McCue/CBC)

The duo found that students slept 7.67 hours on school nights, on average.

What surprised them was that more than a third of students would be classified by the Epworth test as having "excessive" daytime sleepiness, which, in some cases, warrants medical attention.

"Everybody is so stressed with all the work and they're not getting enough sleep," Atkinson says.

"They just have so much on their plate and they're not getting enough time to restore their bodies."

Indeed, national statistics show millions of Canadian adolescents don't get enough shut-eye, which has experts warning of long-term health consequences — unless we start appreciating the importance of a good night's sleep.

'Functioning sub-optimally'

The recommended amount of sleep for 13- to 18-year-olds is eight to 10 hours per night, according to the Canadian Paediatric Society.

Studies suggest more than half of Canadian teens get much less, about 6.5 to 7.5 hours per night, says Indra Narang, director of sleep medicine at Toronto's Hospital for Sick Children.

"We are in an epidemic of sleep deprivation," said Narang, who foresees cumulative effects that can have an impact on everything from health to work performance.

"In 20 years time, we're going to see a whole generation of adults who are functioning sub-optimally."

'We are in an epidemic of sleep deprivation,' says Indra Narang, director of sleep medicine at Toronto's Hospital for Sick Children, who foresees cumulative effects that can have an impact on everything from health to work performance. (Duncan McCue/CBC)

Teenagers naturally function differently than adults when it comes to bedtimes: they don't run on the same inner clocks.

In early adolescence and puberty, teens experience a shift in their 24-hour biological cycles, known as circadian rhythms. This means peak production of the sleep-inducing hormone melatonin happens later in the evening for teenagers, from roughly 11 p.m. to 8 a.m.

Those hormonal changes have long turned many teens into "night owls," but studies over the past few decades show the pervasiveness of sleeplessness is on the rise.

Reasons vary, from late-night use of electronics and hectic after-school schedules, to increased consumption of high-energy caffeine drinks. Some teens also have sleep disorders from being overweight.

"It's not uncommon for me to see teenagers in my clinic who are telling me that on school nights they go to bed at 1 a.m., 2 a.m., 3 a.m. — and get up at 7 a.m. to go to school," Narang says.

"They're struggling to get in to school for the allocated time. They are sleeping in school. They find it hard to do the homework."

When teens don't get enough ZZZZs, the health dangers range from obesity and diabetes, to depression and substance abuse. Narang says public health officials need to better understand the long-term consequences of sleep deprivation.

"What we don't want to do is miss the opportunity to intervene now, rather than have to intervene [later in life] when they have cardiovascular disease or metabolic disease or strokes or, indeed, dementia."

Later school start times?

One of the questions raised by Horsey and Atkinson's science project is whether a later school start time would benefit students.

Some teens worry that delaying start times could have an impact on part-time jobs or after-school sports programs, but many interviewed for this story were enthusiastic about any opportunity to sleep in.

"If school was a bit later, I could get maybe five or six hours [of sleep] ... which would greatly help in, like, getting better grades," says Grade 12 student Haze Ketcheson, who sleeps on average four hours per night.

He might be onto something, and it's about more than getting enough sleep to avoid dozing off in class and missing an important lesson.

Some teens at Smiths Falls District Collegiate say they worry that delaying school start times could have an impact on part-time jobs or after-school sports programs, but many interviewed for this story were enthusiastic about any opportunity to sleep longer in the morning. (Duncan McCue/CBC)

Stuart Fogel, a professor at the University of Ottawa's Sleep Research Laboratory, has been looking at what the brain does while we sleep. He's interested in how each day's experiences are moved from the hippocampus, a limited space where we store recent short-term memories, to the prefrontal cortex, the brain's "hard drive" where we store important memories for long-term reference.

Fogel's research indicates that sleep basically cleans up the hippocampus, leaving us ready to take in fresh data — and simultaneously helps convert short-term memories into long-term ones so we can recall them later.

"What's intriguing is that sleep loss will have an impact on your ability to retain anything that you learn that's new," Fogel says.

Narang says studies of American high schools with delayed start times suggest it can lead not only to significantly increased attendance, but also better grades.

However, there can be a host of logistical challenges to changing school start times. In Smiths Falls, for example, where the student population is largely rural, budget restrictions on school bus services resulted in staggered start times at elementary and secondary schools that allow for buses to make two runs. High schools get the earlier start.

"We think they should push it to nine o'clock ... all they have to do is switch our bus times with the elementary school kids," Atkinson says.

In the meantime, Horsey and Atkinson's school project on sleep nabbed a gold medal at the science fair, and it has been attracting plenty of interest from students and teachers.

It also caught the attention of Horsey's mother Veronica, who happens to be chair of the school council.

"Unfortunately, most adults don't even understand how sleep deprived we are," says Veronica Horsey. "Can we just look at the bigger picture on how to help our teenagers get more rest?"

She's now working with school administrators to find sleep solutions, including workshops to improve students' bedtime routines and scheduling fewer early-morning tests.

More from CBC

Watch The National's story on sleep and teens:

About a third of Canadian kids and adults don't get enough sleep. For teens, 'enough' is generally around eight to ten hours, but many are getting much less. Not getting the suggested hours of sleep has been linked to problems with memory, concentration, motivation and school performance. So what's keeping teens up later into the night? And what can be done to prevent it? 9:34

Watch The National's story on how important sleep is to learning and forming memories: