Some school boards in Canada are switching to later start times for sleepy teens.

Teenagers often struggle to resist the snooze button and get to class on time. Researchers say they have biology backing them up.

The hormonal changes of puberty include later secretion of the hormone melatonin, which signals that it's time to go to sleep, said Reut Gruber, a psychiatry professor at McGill University in Montreal and chair of the Canadian Sleep Society's pediatric sleep group. The signal to get up in the morning is also later, Gruber said.

When teens are chronically sleep deprived, their behaviour and school performance can suffer, a child psychologist says. (iStock)

"All this makes bed time pretty challenging and pushes it to be very late, yet school doesn't change," Gruber said.

In general, teens need nine hours of sleep at night. Otherwise, they can end up chronically sleep deprived, and that daytime tiredness can harm their behaviour and performance in school, Gruber noted.

In the last few years, some high schools in British Columba, Saskatchewan and Ontario have explored the idea of ringing the morning bell later.

Three years ago, Toronto's Eastern Commerce Collegiate Institute moved first period from 9 a.m. to 10 a.m., giving students an extra hour to sleep in.

"I think that we can't deny that when students are well rested, their physical and mental health improves, and that just leads to academic success being supported more readily," said Jennifer Chan, principal at Eastern Commerce.

Eastern Commerce basketball player Sami Hill says the school's later start helps during her first period classes. (CBC)

"I was definitely more awake for first period and a lot more ready to learn," agreed 10th grader Sami Hill, a basketball player at Eastern.

This school year, four secondary schools in the Regina Catholic board are starting classes later at 9 a.m.

"There's lots of evidence that adolescents learn better later in the day," Pitre said. School administrators hope that first period attendance will improve and that there will be fewer interruptions to instructional time.

So far, most of the evidence comes from the U.S., where some schools began to delay their usual 7:15 a.m. start time, said Karen Wilkinson, superintendent of education at the Thames Valley District School Board in London, Ont.

"Their late start is really our current start," Wilkinson said. "What we found is that most of the research didn't pertain to what we do in Canadian schools."

Trustees for the Thames Valley board are reviewing Canadian and U.S. research and will reconsider later start times again in January.

Attention benefits

The students themselves were split about later starts, with some expressing concerns about how it could affect their part-time jobs and extra-curricular activities and others saying they like the idea, Wilkinson said.

"Later school start times for secondary grades have been shown to improve sleep-debt, punctuality, attendance, behaviour, sociability and continuous enrolment, particularly for the at-risk student population," a literature review by researchers at Carleton University concluded.

Work in the sleep lab backs up what school experiments with bell times in Canada and the U.S. have found.

When Gruber asked students to add about an hour of sleep, she observed improvements in their performance on attention tasks and better reports from their teachers.

Students on regular school start times attest to feeling sleep deprived.

"For sure, I’m tired," said 16-year-old Sarah Habbouchi. She attends Maple High School north of Toronto, where classes start at 8:45 a.m. "First two periods, just don't talk to me."

Similarly, Sabra Salim, 14, said she'd wake up at 1 p.m. during summer vacation. "Struggling to get up," she said of the transition back to class.

The girls tended to say social media use like looking at photos of celebrities kept them up while boys were more likely to delay hitting the sack by playing video games.

As for whether teens would just go to bed an hour later with delayed school starts, Gruber said the research suggests they go to bed at the same time and do actually benefit from the extra sleep.

With files from CBC's Kim Brunhuber and Marijka Hurko