Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
Sleep, Exercise & Hormones | Kids & Exercise | What About Average Adults?
Effects of Moderate Exercise | Helpful Tips
Overview
For most of us, moderate, regular exercise has many well-documented health benefits, including improved sleep quality and duration.
Studies show that lack of sleep impairs cognitive performance, mood, metabolism, appetite, and immune and endocrine function, significantly affecting exercise and physical performance.
However, the question remains: does more exercise equal more sleep, or is the answer more specific and targeted?
Keep reading to find out how you can achieve and maintain optimal sleep patterns while following a healthy fitness routine.
Sleep, Exercise & Hormones
Sleep and exercise have a symbiotic relationship. On the surface, it’s easier to sleep after you exercise, and it’s easier to work out after a good night’s sleep.
The connection between sleep and exercise is anecdotally observed relatively early in life. Even as children, we are encouraged to burn off energy to help us settle down for a good night’s sleep.
Although the specific physiological factors by which the two interact are still not fully understood, a deeper correlation between physical activity and sleep quality has been observed in recent studies.
If we start looking further into this relationship, we will find that hormones play a significant role and can be considered a key driver in how well we sleep.
Exercise elevates the heart rate, core temperature, and sweat output, “exciting” the nervous and endocrine systems.
The more vigorous and strenuous the physical activity, and the longer the session, the longer the body will remain in an aroused state.
Two hormones in particular play a significant role in post-workout sleep quality: norepinephrine and cortisol.
Norepinephrine
Together with adrenaline, norepinephrine works to provide some important functions:
- Increases heart rate
- Increases blood pumping from the heart
- Increases blood pressure
- Helps break down fat
- Increases blood sugar levels to provide more energy to the body
In theory, exercise is exciting to the body, resulting in the release of adrenaline and norepinephrine. Adrenaline levels tend to fall off rapidly post-exercise, but norepinephrine levels can stay elevated for up to 48 hours after strenuous exercise.
This reaction can help explain why evidence suggests that athletes may experience reduced quality and quantity of sleep.[1]
Cortisol
The stress hormone cortisol plays an essential role in multiple functions:
- Regulates how your body uses macronutrients, such as proteins, fats, and carbohydrates
- Controls inflammation
- Regulates blood pressure
- Increases blood sugar
- Influences the sleep/wake cycle
- Allows an increase in energy for better handling of stress
Researchers conducted a test on male athletes to determine the impact of exercise on hormone secretion while sleeping. The study suggested that cortisol and growth hormone levels during sleep showed a disturbance of normal functions due to daytime exercise.[2]
Kids & Exercise
Remember that part about kids burning off energy to settle them down for bedtime?
A study that reviewed the sleep of children found that as activity levels and exercise intensify from light to moderate to vigorous, sleep duration actually decreased.[3]
It appears that there really is “too much of a good thing” for physical activity and overstimulation for a good night’s rest, at least if you’re an elite athlete or a child.
What About Average Adults?
Here’s where the potential sleep benefits of exercise become clearer. A recent study focusing on non-athletic level adults and older adults found that regular, moderate exercise had significant, positive effects on overall sleep duration and quality.[4] This result was observed with both cardio and resistance training.
However, there is a caveat: those same ‘average’ individuals who exercised excessively experienced disturbed sleep.
In women, overtraining can lower progesterone and estrogen, which can cause insomnia. This effect holds especially true when the exercise is performed 3 hours or less before bedtime.
Effects of Moderate Exercise
The best possible sleep quality and duration appear to be with moderate levels of exercise, instead of the type of high-volume, a high-intensity approach seen in athletes and very active children.
According to the CDC, moderate-intensity aerobic activity is any physical output that raises the heart rate and breaks a sweat, such as riding a bike or walking fast, and should be done for at least 150 minutes every week.
Muscle-strengthening activities that work all major muscle groups (legs, hips, back, abdomen, chest, shoulders, and arms) should be performed two times per week or more.
Moderate exercise that doesn’t reach elite athletic levels is a realistic limit for most people, and will most likely not adversely affect hormone levels to the point of lowering sleep quality.
Helpful Tips
- Maintain Fitness: As a rule, the more fit you are, the better your body’s hormonal coping mechanisms will be in dealing with the acute stress from workouts. Get at least the recommended 150 minutes per week of moderate aerobic exercise and two-weight resistance training sessions.
- Minimize Stress: The stresses we carry from our jobs, family issues, overtraining, etc., send cortisol levels skyrocketing. Meditate, take a mindful walk or do some relaxing reading. The key is to learn to let go of what you can’t control.
- Reduce Stimulants: Substances like caffeine may help with focus and awareness, but consumption doesn’t offer added energy. If you like caffeine, your best bet is to have it before a workout, but not if it’s close to bedtime to avoid overstimulation.
- As for our more elite athletes, carbohydrate, tryptophan, valerian, melatonin, and other nutritional remedies show promising potential interventions to induce higher quality sleep. [1]
Conclusion
As with many other things in life, finding a healthy balance is vital. The close relationship between sleep, exercise, and the hormonal functions that balance them is certainly no exception.
The good news is that lifestyle changes can manage negative effects on sleep quality. If you have tried some of these changes and are still experiencing negative impacts on your sleep health, please consult a doctor.
References:
- Halson S. L. (2014). Sleep in elite athletes and nutritional interventions to enhance sleep. Sports medicine (Auckland, N.Z.), 44 Suppl 1(Suppl 1), S13–S23. https://doi.org/10.1007/s40279-014-0147-0
- Kern, W., Perras, B., Wodick, R., Fehm, H. L., & Born, J. (1995). Hormonal secretion during nighttime sleep indicating stress of daytime exercise. Journal of applied physiology (Bethesda, Md. : 1985), 79(5), 1461–1468. https://doi.org/10.1152/jappl.1995.79.5.1461
- Williams, S. M., Farmer, V. L., Taylor, B. J., & Taylor, R. W. (2014). Do more active children sleep more? A repeated cross-sectional analysis using accelerometry. PloS one, 9(4), e93117. https://doi.org/10.1371/journal.pone.0093117
- Kredlow, M. A., Capozzoli, M. C., Hearon, B. A., Calkins, A. W., & Otto, M. W. (2015). The effects of physical activity on sleep: a meta-analytic review. Journal of behavioral medicine, 38(3), 427–449. https://doi.org/10.1007/s10865-015-9617-6
