The Sleep Loop: How Better Rest Powers Better Running

Why Your Training Starts With Sleep

By Lori McGee Koch, PhD   

Every runner has heard about the importance of mileage, strength work, and recovery days. But there’s a behind-the-scenes system that’s just as critical to your performance: your circadian rhythm and sleep.

Your circadian rhythm is your body’s internal clock. It governs when you feel awake, when you get tired, how you digest food, how you regulate hormones, and how you recover from exercise. When that rhythm is steady and consistent, your body operates efficiently. When it’s thrown off by inconsistent sleep, irregular eating, or erratic workout times everything can start to feel harder.

For runners, this matters more than most people realize. When your sleep and daily routine are out of sync, your body struggles to process fuel properly, which can make workouts feel sluggish. Your perceived effort increases, even if your paces stay the same. Your recovery slows because growth hormone, which helps repair muscles and build strength, is primarily released during the first few deep sleep cycles. And when you don’t sleep enough or your sleep is disrupted, you’re also more likely to experience changes in metabolism. Cortisol, the stress hormone, tends to rise when you’re sleep deprived, leading to cravings, increased fat storage, and a higher risk of injury or burnout.

So how do you keep your circadian rhythm and your training on track?

The first step is to create more consistency in your daily routine. Try going to bed and waking up at the same time every day, even on weekends. This simple habit helps anchor your sleep/wake cycle and supports better energy throughout the day. In the morning, get outside or near natural light as early as you can. Morning light is one of the most powerful signals to your brain that it’s time to be alert, which in turn helps regulate your sleep at night.

At the end of the day, develop a wind-down routine that prepares your body for rest. Turn off screens about an hour before bed. The blue light from devices interferes with melatonin release, making it harder to fall asleep. Keep your bedroom cool and dark most research supports a temperature between 60 and 67 degrees Fahrenheit for optimal sleep. Avoid heavy meals right before bed, but if you’re hungry, a light snack with carbohydrates and protein can support overnight muscle repair.

Your workouts play a role here too. While exercise generally improves sleep, intense late-night sessions can leave your heart rate elevated, body temperature high and delay the body’s natural transition to sleep. If you notice that evening runs make it harder to fall asleep, try shifting your harder workouts to earlier in the day.  

Naps are another tool that can support recovery, but timing is key. A 20- to 30-minute nap in the early afternoon can give you a boost without interfering with nighttime sleep. If you’re really fatigued, a longer nap, about 90 minutes, allows for a full sleep cycle. Just be mindful of napping too close to bedtime.

And if you find yourself awake in the middle of the night? It happens. The best thing you can do is get out of bed, move to a quiet, dim space, and do something calming until you feel sleepy again. This prevents you from lying awake feeling frustrated, which can make the problem worse.

Sleep isn’t optional if you want to improve as a runner. It’s a core part of your training, just as important as long runs, intervals, or strength work. When you get your circadian rhythm dialed in, everything else starts to fall into place. You’ll recover faster, handle mileage better, recover faster and enjoy running more.

So the next time you think about trading sleep for one more task, remember—sometimes the best way to move forward is by staying still.