You wake up at 5am, lace up before the house stirs, and log your miles before work demands your attention.
It’s the only way to make training fit. Millions of runners do exactly the same thing every day.
But there’s a cost that doesn’t show up in your training log: the sleep you’re cutting short to make that run happen.
A growing body of research suggests that chronic sleep restriction isn’t just a recovery inconvenience. It may be one of the most underappreciated injury risk factors in distance running.
And a 2025 study conducted specifically on non-elite runners now provides the clearest evidence yet that poor sleep and injury risk are directly linked.
So, in this article we’re going to break down the research into practical advice on…
- What a new study of 425 runners revealed about sleep profiles and injury probability
- The science on why poor sleep makes you vulnerable to injury
- The exact hours threshold research shows leads to increased injury risk
- Why it’s not about “how much” sleep you get but about “the quality of a sleep you get”
- A specific protocol to protect your sleep and your training
A New Study Changed What We Know
Researchers de Jonge and Taris published a 2025 study in Applied Sciences that took a more sophisticated approach to measuring sleep than most prior research [1].
Rather than simply asking how many hours runners slept, they used a statistical technique called latent profile analysis to classify 425 runners into four distinct sleep profiles based on three dimensions: duration, quality, and the presence of sleep problems.
The four profiles were Steady Sleepers (48% of the sample), Poor Sleepers (37%), Efficient Sleepers (8%), and Fragmented Sleepers (7%).
Steady Sleepers had average duration, above-average quality, and few sleep problems, making them the functional baseline for the study.
Poor Sleepers were the concerning group: shorter duration, low quality, and high rates of problems including difficulty falling asleep, frequent nighttime waking, and waking unrefreshed regardless of hours logged.
The study found that Poor Sleepers were 1.78 times more likely to report a running injury than Steady Sleepers.
The odds ratio was 1.78 (95% CI = 1.14 to 2.78; p = 0.01), with a 68% probability of sustaining an injury over a 12-month period.
No other sleep profile showed a statistically significant difference in injury rates.
Sixty percent of all runners in the study reported at least one injury in the prior year, a reminder that running injuries are not rare exceptions but near-universal experiences for runners who train consistently.
The study controlled for gender, age, BMI, body height, and running experience, making the injury risk finding specific to sleep rather than these other factors.
What “Poor Sleep” Actually Means
Most runners equate sleep quality with hours on the clock, but research from the 2025 study tells a more nuanced story.
The Poor Sleeper profile wasn’t defined by dramatically short sleep alone.
It was the combination of insufficient duration, poor subjective quality, and persistent sleep problems that created injury risk.
This matters because you can sleep six and a half hours and fall into either the Steady Sleeper or Poor Sleeper category depending on whether you actually feel rested, whether you’re waking multiple times, and whether sleep problems are a regular experience for you.
The runner who lies awake for 45 minutes before falling asleep, wakes at 3am with a mental to-do list, and rises feeling unrefreshed is the Poor Sleeper even if their total hours look passable on paper.
Two Biological Reasons Poor Sleep Raises Your Injury Risk
Even where population studies have been mixed, the biological mechanisms connecting sleep deprivation to injury vulnerability are well-established.
There are two primary pathways.
Your Body Loses Its Repair Window
Research confirms that deep NREM sleep, specifically stage N3 or slow-wave sleep, is when growth hormone secretion peaks and drives protein synthesis and tissue repair throughout the body [3].
Running creates microscopic tears in muscle fibers, tendons, and connective tissue with every session.
Those microtraumas are normal and expected. They’re part of the adaptation process, but they require that deep sleep repair window to resolve before your next run.
Research published in Physiological Reports found that a single night of sleep deprivation reduced muscle protein synthesis by 18%, raised cortisol by 21%, and lowered testosterone by 24% compared to normal sleep [4].
That hormonal shift creates an acute catabolic environment, where the body breaks down tissue faster than it rebuilds it.
A review in Current Sports Medicine Reports confirmed the critical threshold:
Sleeping 7 hours or fewer per night, sustained for at least 14 consecutive days, is associated with 1.7 times greater risk of musculoskeletal injury compared to sleeping more [2].
The same review found that suboptimal sleep more consistently predicts next-day pain than pain predicts subsequent sleep loss, suggesting sleep impairment comes first in the chain of events, not as a secondary consequence [2].
Your Neuromuscular System Starts to Fail
Research shows that sleep deprivation impairs reaction time, proprioception, balance, and neuromuscular coordination, and these effects accumulate with chronic restriction [5].
For runners, this matters more than it might seem.
Running economy and injury prevention both depend on precise neuromuscular control.
These are the micro-adjustments your body makes on uneven terrain, the coordination between hip abductors and knee stabilizers during fatigue, the proprioceptive feedback that keeps your foot strike consistent through miles 14 to 20 of a long run.
Studies show that sleep-deprived athletes exhibit measurably poorer technique and biomechanical control, and that fine motor tasks requiring cognitive involvement are more affected than gross motor patterns [5].
Your cardiovascular system may hold up well enough on shortened sleep, but the subtle coordination that protects your knees, ankles, and hips during high-mileage weeks is quietly degrading.
A review published in Sleep Medicine Clinics confirmed impaired reaction time, coordination deficits, and hormonal disruption as the primary injury-driving pathways for sleep-deprived athletes [6].
How Much Sleep Do Runners Actually Need?
The 2021 international expert consensus on sleep and athletes, published in the British Journal of Sports Medicine, recommends 7 to 9 hours per night for healthy adults and 8 to 10 hours for adolescents [7].
Research places the injury risk threshold at 7 hours per night, but only when that shortfall is sustained for at least 14 consecutive days, not just occasionally.
The de Jonge study explicitly noted that non-elite runners balancing training with work and family likely need to aim for the upper range of those recommendations, not the lower end.
A 52-week prospective study of 95 endurance athletes confirmed the relationship in this population:
sleeping fewer than 7 hours per day over 14 days increased new injury risk by 51%, while sleeping more than 7 hours per day reduced new injury risk by 37% [8].
A Practical Protocol to Protect Your Sleep
The most important shift is treating sleep as a training input, not a lifestyle choice that yields to everything else on your calendar.
The international expert consensus provides a concrete framework for doing exactly that.
Target 7.5 to 9 hours depending on your current training load, and prioritize consistency of schedule first: a regular bedtime and wake time stabilizes your circadian rhythm faster than chasing extra hours whenever they happen to be available.
If you’re in a high-volume training block, treat additional sleep the same way you’d treat an easy recovery run. It’s not optional, and it’s worth protecting from schedule compression.
Research also supports strategic napping: a 20-minute nap between 1pm and 4pm can offset some of the neuromuscular and hormonal deficit from a shortened night without disrupting your evening sleep [7].
Four sleep hygiene practices have the strongest research support:
- No caffeine after 2pm
- Morning light exposure within 30 minutes of waking
- A cool and dark sleep environment
- A screen-free wind-down of at least 30 minutes before bed
You can read a more detailed breakdown of how these strategies apply specifically to runners in our guides on pre-race sleep strategies and how to sleep better as a runner.
If the biggest barrier for you is quality rather than hours, the research on the Poor Sleeper profile suggests that addressing sleep quality is as important as protecting sleep duration.
Some runners find targeted supplementation helpful here, particularly for managing the elevated cortisol that often follows hard training days and disrupts the transition into deep sleep.
That’s why the sleep supplement I always recommend is MAS Sleep.
Unlike a lot of mainstream sleep supplements, it was formulated specifically the help lower cortisol and stress and improve the deep sleep needed for recovery, rather than “knocking you you out”.
It also contains no melatonin, which means no morning grogginess and no risk of dependency, and can be taken nightly during high-training-load periods when recovery demands are highest.
The Bottom Line
The research doesn’t support a simple, universal rule that sleeping less than a fixed number of hours will cause your next injury.
What the evidence does support, particularly the 2025 runner-specific study, is that runners who consistently struggle with sleep duration, quality, and sleep problems face meaningfully higher injury probability than those who sleep well.
The mechanism is biologically clear: tissue repair requires deep sleep, neuromuscular coordination degrades with chronic sleep restriction, and the hormonal environment created by sustained poor sleep is catabolic rather than restorative.
If you’re treating sleep as the first variable to sacrifice when training and life compete for time, you’re making your injury risk harder to manage, not easier.
The 5am alarm isn’t going away for most of us, but making sure what comes before it is actually protective sleep is something you can work toward, systematically, starting tonight.
