It’s common knowledge teens need a good night’s sleep to function well. But recent Brock University-led international research has raised the stakes on what could happen if their slumber is inadequate.

“We observed a substantial risk of injury in adolescents who reported having poor sleep,” says PhD student Valerie Pagnotta (BSc ’21, MSc ’23), lead author of the cross-national study “Sleep difficulties as a consistent risk factor for medically treated injuries among adolescents in 46 countries.”

The worse the quality and quantity of sleep, the greater the risk of any or multiple injuries, says Pagnotta. Girls with poor sleep were particularly vulnerable to being injured.

The six-member research team set out to investigate the association of inadequate sleep to injuries in 46 countries.

Using records from the World Health Organization’s ongoing Health Behaviour in School-Aged Children (HBSC) survey and involving multiple international investigators in the HBSC network, the research team surveyed 230,000 adolescents aged 11, 13 and 15 in Canada and 45 European countries.

Participants reported on their sleep behaviours, including how often they experienced difficulties falling asleep, insufficient quality and quantity of sleep on school and non-school days, and social jetlag, which refers to different sleep patterns during weekends and other non-school days.

Adolescents were also asked how often they had experienced an injury that required medical treatment from a doctor or nurse in the past year as well as if they had sustained a more serious injury that required a cast, stitches or surgery.

The findings from the teens’ self-reported surveys include that:

• 48 per cent had insufficient sleep on school days compared to 13 per cent on non-school days
• 44 per cent had one injury, with 21.5 per cent experiencing multiple injuries
• girls universally reporting higher proportions of sleep difficulties across each of the 46 countries
• adolescents reporting difficulties in falling asleep were at the highest risk of experiencing any, and multiple, injury in all countries
• girls displayed greater risks for one or more injuries compared to boys, regardless of the sleep indicator

Pagnotta says adolescence is a particularly important time for physical, emotional and social growth and development.

“If adolescents are not getting enough sleep or they’re having sleep difficulties, that can impair their cognitive functioning especially in the areas of social information processing, attention and decision making,” she says.

“We think these impairments may contribute to increased risk of injury among adolescents,” she says, adding that the greater injury risk observed among girls needs further investigation.

Mentoring Pagnotta on the study were Brock Professor of Health Sciences William Pickett and Professor of Public Health Medicine Peter Donnelly at the University of St. Andrews in the U.K.

Pickett co-leads the HBSC study in Canada under the World Health Organization’s HBSC survey.

He says the relationships Pagnotta uncovered between sleep and injury are ” so consistent, and so powerful, that they can’t be ignored in health policy efforts.”

“From a policy perspective, we think it is helpful for clinical and public health professionals to have data like this to support their efforts to advise their patients and populations around the importance of sleep hygiene, especially in children,” he says.

The latest study, published last month in the European Journal of Public Health, was funded by the Public Health Agency of Canada. The federal government’s Canadian Institutes of Health Research Michael Smith Foreign Study Supplement and Canada Graduate Scholarship — Master’s supported Pagnotta’s work.

The latest research builds on an earlier study conducted by Pagnotta, Pickett, Professor of Health Sciences Jian Liu and Assistant Professor of Health Sciences Michelle Vine.

Their study, “Insufficient sleep, impaired sleep and medically treated injury in Canadian adolescents: a national cross-sectional study,” also found an association between sleep deficits and injury, calling impaired sleep a “quiet epidemic” affecting up to one-third of Canadian teens.