Sleep has long been considered the "silent foundation" of recovery, yet many runners underestimate its role. According to a University of South Australia study published in Applied Sciences in early November, individuals with insufficient or poor-quality sleep were up to 1,78 times more likely to experience injuries than runners with good sleep.

Runners with insufficient or fragmented sleep are more prone to injuries during training. *Photo: Marathon Handbook*

Injury risk rises sharply with insufficient sleep

The study tracked 425 recreational runners over one year, collecting data on sleep duration, ease of falling asleep, number of nighttime awakenings, and morning fatigue. Results indicated that runners who slept below recommended levels, struggled to fall asleep, or frequently woke up at night had the highest increased risk of injury.

Lead researcher Jan de Jonge stated: "Runners often focus on mileage, nutrition, and recovery methods like massage or ice baths. However, sleep is frequently overlooked. Our data shows that the group with poor sleep had nearly double the injury rate of those with good sleep."

How sleep affects a runner's body

Experts explain that sleep is when the body undergoes tissue repair and regeneration. Insufficient or fragmented sleep disrupts these recovery mechanisms, leading to:

- Reduced ability to repair micro-injuries in muscles and tendons after long runs or high-pace sessions. A 2011 Stanford University study showed that runners who slept more (about 10 hours daily during the trial) significantly improved speed, reflexes, and reduced fatigue.

- Hormonal imbalance, particularly involving cortisol and growth hormone – two factors critical for recovery speed. Research in Sleep Medicine Reviews (2018) confirmed that sleep deprivation leads to prolonged elevated cortisol, making the body more prone to inflammation and injury.

Runners can monitor their sleep using sports watches. *Photo: Trang Dem*

- Decreased concentration and motor coordination. This makes runners more susceptible to tripping, missteps, or incorrect foot strikes – common causes of knee, ankle, and IT band injuries. According to an American Academy of Sleep Medicine study, sleep loss can reduce reaction time by 20-30%.

- Increased risk of overload when combined with heavy training schedules or stressful work, preventing soft tissues from recovering adequately.

Runners who described their sleep as "fragmented," "shallow," or "never feeling refreshed" recorded the highest number of injuries during the survey year.

Sleep must be considered part of a running plan

The number of recreational runners in Vietnam and worldwide is growing rapidly, leading to a rise in injury rates. According to sports experts from the US and Europe, sleep should be prioritized equally with recovery runs or strength training.

The National Sleep Foundation recommends that general runners get 7-9 hours of sleep per night, and an additional one to two hours when increasing training volume or preparing for marathons or ultra-races.

Some simple but effective habits to improve sleep:

- Maintain a consistent sleep-wake schedule.

- Limit caffeine intake after 14h.

- Reduce blue light exposure from phones one hour before bedtime.

- Keep the bedroom cool, around 20-25 degrees C, dark, and quiet.

- Avoid intense exercise too late in the evening.

Beyond the exhilaration and health benefits of running, sufficient sleep helps runners recover better and reduces injury risk. *Photo: adidas Runners Hanoi*

Experts at the Stanford Sleep Disorders Clinic emphasize that even improving sleep quality for two to three weeks can lead to noticeable changes in recovery perception and reduced injury risk.

Data from the new University of South Australia study reinforces a seldom-mentioned fact: a training plan may be perfect, but without adequate sleep, all efforts are undermined. Sleep is not a "supplementary" part of running. It is a pillar of recovery, determining a runner's endurance, speed, and most importantly, safety.

Compiled by Nhat Tao