Sleep and Injury Risk in Young Athletes: What the School Year Changes

School goes back this week, and for a lot of young athletes on the North Shore two things change on the same day. Training load goes up, because school teams and club seasons start again. Sleep goes down, because early start times come back. Those two changes push in opposite directions, and the research on adolescent athletes suggests the combination matters.

What the research found

The clearest summary comes from a systematic review and meta-analysis in the Journal of Pediatric Orthopaedics. The authors screened 907 articles, seven met their criteria, and five of those seven individually reported that adolescents who chronically slept poorly had a significantly higher chance of a sport or musculoskeletal injury. Pooled together, the odds ratio was 1.58.

The most cited single study behind that finding is Milewski and colleagues, also in the Journal of Pediatric Orthopaedics. Adolescent athletes who slept fewer than 8 hours per night were about 1.7 times more likely to sustain a sport-related injury than those sleeping at least 8 hours. A review in Sports Health summarises that result alongside the wider literature on young athletes and sleep.

Both are observational studies. They establish that short sleep and injury turn up in the same young athletes, and that design cannot pin any one injury on sleep. The meta-analysis authors were blunt about a second limit too: current research cannot yet determine the effect of acute lack of sleep on injury rates. So one late night before a game sits outside what this evidence covers. Weeks of short sleep stacked on each other is the part it does cover, and that is exactly what a school term builds.

The recommended hours, and how far most teenagers are from them

Canada has a published number. The Canadian 24-Hour Movement Guidelines, developed by the Canadian Society for Exercise Physiology with the Public Health Agency of Canada and others, recommend 9 to 11 hours of sleep per night for ages 5 to 13 and 8 to 10 hours for ages 14 to 17, with consistent bed and wake-up times. The same guidelines ask for at least 60 minutes of moderate to vigorous activity a day.

Those hours are the recommendation for every young person in that age range. A teenager training four or five days a week belongs at the top of it, because sleep is when the body adapts to the work it has done.

Most are well short. The Sports Health review describes a study of 196 competitive athletes aged roughly 14 to 17 in which only 52 percent slept 8 hours or more, and about 15 percent slept under 7 hours. In a team of twenty, that puts close to half below the recommended range on an ordinary night, before any homework deadline or late bus ride home from a game.

Why September is the month this shows up

Through July and August, sleep mostly looks after itself. No early alarm. Training in the afternoon. A late night costs nothing the next morning. School puts the alarm back in the room and pushes practice to the end of the day, and it does both in the same week.

In our clinic the first wave of young overuse complaints tends to arrive around the fourth or fifth week of term. That timing fits a load that climbed faster than recovery could match. The athlete feels fine through the first several sessions, then a knee or a heel starts talking. This one comes from our own appointment book, so it carries the weight of a clinic pattern and no more. It does line up with what happens when training rises while sleep falls.

The same weeks are when growth-related complaints turn up. If a young athlete is in a growth spurt, the load conversation matters more, and it is worth reading about growth plate injuries in youth athletes and Osgood-Schlatter knee pain in teenagers alongside this.

Short sleep shows up as a change in how they move

In sleep-deprived high school athletes, reaction time gets worse as the week goes on. The Sports Health review describes performance on a psychomotor vigilance test, a standard measure of reaction time and attention, declining progressively across the week, with the worst results on Fridays. The review also notes that without enough sleep after hard exertion, athletes may have impaired muscle recovery, less power and endurance, and more soreness.

Friday is often when the game is. So a tired athlete is at their least sharp on the day they are asked to be sharpest. For a parent or a coach the useful part is knowing what that looks like from the sideline, because teenagers almost never say they are tired. They land more heavily instead. They lose position in the last twenty minutes, or take longer to settle after each session than they did in August.

What we ask about in an assessment

When a young athlete comes in with an overuse complaint, the injury itself is only part of the picture. We ask what the week actually looks like: how many sessions, how many are the same sport, what time practice finishes, how long the trip home takes, when homework gets done, and what time the alarm goes off. That last question changes the plan more often than people expect.

We also ask how the pain behaves within a session. Pain that arrives earlier each week at the same point in practice usually means load and recovery are out of balance, whatever the tissue involved. Our physiotherapy for youth athletes service page covers how that assessment runs.

Sleep is one input among several here. Training volume, how much of the week goes into a single sport, and growth all matter too. The related problem of doing one sport year-round is covered in our post on sport specialisation and overuse injury, and the load-building side is in pre-season conditioning.

Changes that fit inside a real school week

The advice that fails is the advice that asks a family to rebuild their evening. A few smaller adjustments hold up better through a term.

Keep the wake-up time steady, including on weekends where the schedule allows, since the guidelines ask for consistent bed and wake times alongside a total. Move the homework block earlier on training nights, because the session that ends at nine is what pushes the whole evening back. Eat straight after training, so the last hour before bed stays clear of a meal. Where a family has a long drive back from a game, plan the following morning as a recovery morning.

On a day after genuinely short sleep, adjusting the session works better than cancelling it. Keeping the skill work and cutting the highest-intensity block preserves the routine while removing the part with the most risk. That plan works far better when the coach hears about it in advance.

When to book an appointment

See a physiotherapist when a young athlete has pain that keeps returning at the same point in a session, pain that has lasted more than two or three weeks, or a growing area of soreness around a joint during a growth spurt. Get prompt medical assessment instead if the pain started suddenly with a specific incident, if they cannot put weight through the limb, or if there is swelling that came on quickly, since those need a different workup.

Book a 30-minute appointment and we will assess the complaint, map out what the training week and the recovery week actually look like, and set a plan that survives a school term. You can see what we treat or reach the clinic here.

This article is general information about sleep, training load, and injury risk in young athletes. It is not personal medical advice. A regulated practitioner can confirm whether the patterns described apply to your child.

Sources

• Lack of Sleep and Sports Injuries in Adolescents: A Systematic Review and Meta-analysis, Journal of Pediatric Orthopaedics (2019)
• Chronic Lack of Sleep is Associated With Increased Sports Injuries in Adolescent Athletes, Journal of Pediatric Orthopaedics (2014)
• Sleep and the Young Athlete, Sports Health (2022)
• Canadian 24-Hour Movement Guidelines for Children and Youth, Canadian Society for Exercise Physiology
• College of Health and Care Professionals of BC, public directory

This article is for general information only and does not constitute medical advice, diagnosis, or treatment. Individual presentations vary — assessment findings and treatment plans differ from person to person. If you are experiencing severe symptoms, neurological changes (numbness, weakness, bowel or bladder changes), or a significant trauma, contact your physician or emergency services. Care at Medstar Sport Physio & Health is provided by practitioners registered with their respective British Columbia regulatory colleges.