Your Athlete's Most Overlooked Training Session

One habit, three risks

One everyday habit is linked to more sports injuries, a higher risk of concussion, and slower reaction time. That habit is poor sleep.

I'm Dr. Linda Kim, a sports psychiatrist and the mom of three competitive athletes. Families track practice hours, nutrition, and private lessons closely. Sleep is usually the first thing to go when the schedule gets tight. The research says it should be the last.

Poor sleep and sports injury

Teen athletes who chronically sleep poorly have about 60% higher odds of sports injury. A systematic review and meta-analysis pooled studies of adolescents under 19 and found an odds ratio of 1.58 (95% CI 1.05 to 2.37). The authors note that the evidence is about long-term sleep habits. It can't yet say whether one bad night raises injury risk.

One of the studies in that review surprised its own authors. Milewski and colleagues surveyed middle and high school athletes about the number of sports they played, their training time, private coaching, strength training, and sleep. The lead researcher said the team expected the number of sports, year-round play, and specialization to matter most. Instead, two factors stood out: hours of sleep and grade in school.

Athletes who slept less than about 8 hours a night were 1.7 times more likely to be injured. Each additional grade in school raised the likelihood 1.4 times. The grade effect may reflect years of accumulated play.

Poor sleep and concussion

In NCAA Division I athletes, moderate to severe insomnia was linked to about three times the risk of concussion over the following year. Raikes and colleagues followed 190 Division I athletes who completed validated sleep questionnaires (relative risk 3.13, 95% CI 1.32 to 7.42).

The link held even after accounting for traditional risk factors such as sport type and past concussions. Frequent daytime sleepiness was also linked to higher risk. The study shows an association, not cause and effect, and the sample was small. Still, sleep is one of the few concussion risk factors that athletes and families can actually change.

Why sleep matters: growth hormone

The body's biggest growth hormone surge comes shortly after falling asleep, during the first period of deep (slow-wave) sleep. Growth hormone drives tissue repair, muscle recovery, and growth in young athletes.

Van Cauter and colleagues showed a consistent link between deep sleep and growth hormone release. Waking up during the night is linked to lower release. That's why bedtime matters as much as total hours. A late night doesn't just make for a tired morning. It cuts into the window when recovery happens.

Sleep and performance

Sleep doesn't just protect athletes. It makes them better. Cutting sleep impairs attention and slows reaction time, and even one night of total sleep loss has measurable effects.

The reverse also holds. In a Stanford study, 11 men's basketball players aimed for 10 hours in bed each night for 5 to 7 weeks and added nearly 2 hours of sleep a night. By the end:

• Their 282-foot sprint time dropped from 16.2 to 15.5 seconds
• Their reaction times improved
• They made more free throws and three-pointers

They added no new drills, only more sleep. The study was small and had no control group, but the results line up with the wider research on sleep and athletic performance.

Your Sunday night reminder

Too many athletes treat running on no sleep like a badge of honor. It isn't. Recovery is training, and it starts tonight.

Three changes to make before the week begins:

1. Lights out 30 minutes earlier. An earlier bedtime protects the first stretch of deep sleep, when growth hormone peaks.
2. Phones charge outside the bedroom. Late-night scrolling delays sleep and fragments it.
3. Treat sleep as part of the training plan. Track it the way you track practice hours. For most teen athletes, the target is 8 to 10 hours a night.

If an athlete regularly struggles to fall asleep, stay asleep, or stay alert during the day, talk with their doctor. Insomnia and daytime sleepiness are treatable.

References

This post is for educational purposes only and is not medical advice.

1. Van Cauter E, Plat L, Copinschi G. Interrelations between sleep and the somatotropic axis. Sleep. 1998;21(6):553–566. Record
2. Gao B, et al. Chronic lack of sleep is associated with increased sports injury in adolescents: a systematic review and meta-analysis. Orthop J Sports Med. 2019. PMC6446394
3. Milewski MD, et al. Chronic lack of sleep is associated with increased sports injuries in adolescent athletes. J Pediatr Orthop. 2014;34(2):129–133. AAP abstract coverage
4. Raikes AC, Athey A, Alfonso-Miller P, Killgore WDS, Grandner MA. Insomnia and daytime sleepiness: risk factors for sports-related concussion. Sleep Med. 2019;58:66–74. PMC7604222
5. Mah CD, Mah KE, Kezirian EJ, Dement WC. The effects of sleep extension on the athletic performance of collegiate basketball players. Sleep. 2011;34(7):943–950. doi:10.5665/SLEEP.1132
6. Charest J, Grandner MA. Sleep and athletic performance: impacts on physical performance, mental performance, injury risk and recovery, and mental health. Sleep Med Clin. 2020;15(1):41–57. PMC9960533
7. Sleep, nutrition, and injury risk in adolescent athletes: a narrative review (National Sleep Foundation recommendation of 8–10 hours for adolescents). PMC10745648