Struggling to Sleep After Exercise? Here’s Why and What to Do About It

Exercise is fantastic for your health, energy levels, and mental wellbeing. But for some, working out—especially intense sessions like marathon training—can lead to unexpected sleep troubles. If you’ve ever found yourself tossing and turning after an evening run, despite feeling exhausted, you’re not alone.

Why Does Exercise Affect Sleep?

While exercise is generally beneficial for sleep, intense physical activity can stimulate your nervous system and elevate levels of stress hormones like cortisol and adrenaline. This can leave you feeling wired rather than relaxed. When you train hard, your body enters a state of heightened alertness, preparing muscles and systems for more action—great for performance, but not for winding down.

According to the Sleep Foundation, while regular physical activity can promote deeper sleep, “high-intensity exercise close to bedtime can delay sleep onset and reduce overall sleep quality” due to increased cortisol and core body temperature (Sleep Foundation, 2023).

Key Reasons Why Sleep Suffers After Exercise:

1. Elevated Cortisol: High-intensity workouts, like marathon training, can spike cortisol levels. A study from the Journal of Sports Science & Medicine found that elevated cortisol in athletes was associated with disrupted sleep patterns and increased difficulty falling asleep (Journal of Sports Science & Medicine, 2020).

2. Increased Body Temperature: Exercise raises your core body temperature. Since sleep is naturally triggered by a drop in temperature, staying too warm post-exercise can hinder falling asleep.

3. Endorphin and Adrenaline Rush: These 'feel-good' hormones may boost your mood, but they also keep your mind active, delaying sleep onset. As Dr. Matthew Walker, neuroscientist and author of Why We Sleep, states: “Sleep is the single most effective thing we can do to reset our brain and body health each day.” High-intensity exercise can disrupt this reset by triggering prolonged periods of alertness.

4. Late-Night Hunger: Post-exercise hunger, driven by a need to replenish glycogen stores, can keep you awake or lead to disrupted sleep if you go to bed too full.

How to Balance Exercise with Sleep

Finding the right balance between exercise and rest is crucial, especially when training for events that push your body to its limits. Here’s how to optimise your routine:

1. Time Your Workouts Wisely
   Try to schedule intense sessions earlier in the day. If evening is the only option, aim to finish your workout at least 3-4 hours before bedtime. This will give your body time to cool down, lower cortisol levels, and enter a relaxed state.

2. Prioritise Restorative Activities
   Integrate yoga, stretching, or gentle walks to balance the intensity of your training. These activities lower cortisol and promote recovery, allowing for better sleep quality.

3. Create a Consistent Sleep Routine
   Establish a wind-down ritual—such as light reading or a warm (not hot) bath—30-60 minutes before bed. Keep the lights dim and avoid screens to allow your body’s natural sleep signals to take over.

4. Fuel Smartly Before and After Workouts
   Eat a balanced meal or snack that includes protein, healthy fats, and carbohydrates post-exercise. This will help stabilise blood sugar and support muscle recovery, reducing the likelihood of late-night hunger.

5. Consider Magnesium-Rich Foods
   Magnesium is known for its calming effects on the nervous system. According to a study published in the Journal of Research in Medical Sciences, magnesium supplementation significantly improved sleep quality in adults experiencing insomnia (Journal of Research in Medical Sciences, 2012). Add foods like leafy greens, nuts, and seeds into your diet or consider a natural magnesium supplement to support muscle relaxation and sleep.

Why Sleep Matters When Training

Quality sleep is the cornerstone of successful training. Without it, your body struggles to repair muscles, process nutrients, and stabilise cortisol levels. Over time, poor sleep can lead to overtraining syndrome—characterised by fatigue, irritability, and diminished performance. Sleep also regulates appetite-controlling hormones, making it easier to manage hunger and cravings during intense training periods.

The Cortisol-Sleep-Hunger Cycle in Marathon Training

Marathon training, while exhilarating, places significant stress on your body. High-intensity workouts trigger cortisol, which not only disrupts sleep but can also increase hunger. This often leads to eating late at night, creating a cycle that keeps you awake and hampers recovery.

Breaking the Cycle:

1. Prioritise Recovery Days: Include at least one rest day per week. Use this time for active recovery like yoga or gentle walks.

2. Adapt Your Sleep Environment: Keep your bedroom cool, dark, and quiet. Consider blackout curtains and a white noise machine to create a calming sleep environment.

3. Limit Caffeine and Alcohol: Both can spike cortisol and disrupt sleep patterns. Swap late-afternoon coffee for herbal teas, and limit alcohol as it interferes with deep sleep cycles.

Finding Balance to Feel Amazing

To achieve peak performance without sacrificing sleep, build your training plan around the three pillars: exercise, nutrition, and rest. By honouring your body’s need for sleep and recovery, you’ll not only train more effectively but also feel energised and strong every day.

As the National Sleep Foundation highlights, “Physical activity is a cornerstone of a healthy lifestyle, but balancing it with restorative sleep is essential for maximising its benefits.” Rest is not a luxury—it’s part of your training strategy. Prioritise sleep as much as you prioritise your workouts, and you’ll set yourself up to feel and perform at your absolute best!