Circadian rhythm - when is the best time to exercise?

Updated: Apr 23

In recent years, many people have been talking about the circadian rhythm. After all, everything around us follows certain cycles and rhythms, which, in a way, allow us to find ourselves in a fast-paced reality.


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The circadian rhythm refers to the day and night cycle and the course of physiological and behavioral processes over 24 hours. This is how long it takes the Earth to rotate on its axis, and we are affected by these movements. If you get enough sleep, don't sleep until noon, don't eat late at night, and if you get enough physical activity, your circadian rhythm is probably the same as if you were living in natural conditions. The more you take care of your natural rhythm, the more resistant you will be to disease (1). Your energy levels will increase, and your metabolism will be more efficient. Taking good care of your circadian rhythm isn't just about keeping track of your ideal sleeping schedule. It also relates to when you exercise and when you are active. In this article, you'll find out the best time to exercise during the day.


Why is circadian rhythm important?

Everything you do during the day affects the quality of your sleep at night. This, in turn, affects the amount of energy you have the next day. By taking care of your body's natural rhythm, you are improving your metabolism, which influences the feeling of hunger or satiety. You also support the functioning of the muscular and skeletal systems (2), but the most important system regulated by circadian rhythm is the endocrine system. Out hormones are responsible for making us feel hungry or sleepy, but they are also the reason why we sometimes feel friskier or prefer to rest on the couch. By taking care of your circadian rhythm, you can have an impact on these aspects of your life - supporting your metabolism, increasing your libido, and significantly improving the quality of your sleep.

So, how can you exercise mindfully to support this rhythm? I'll cover some basic principles to help you choose the right type of activity depending on the time of day.

How can you exercise to support sleep quality?

Physical activity and sleep quality affect each other. This means that you sleep better when you exercise, but at the same time, you feel more energy and desire to move after a good night's sleep. A self-perpetuating cycle, right? Physical activity improves sleep quality by extending your time in that all-important slow-wave phase of sleep (3). But when to exercise, and what type of exercise to choose to support your natural rhythm instead of disrupting it? Timing your workouts is the key.


1. Morning exercise


Exercising in the morning increases the fat you burn (4). This is the fuel your body uses after an all-night fast. Morning is a good time for dynamic but not overly intense activity. Allow your morning workout to wake you up and get you going instead of depriving you of strength for the rest of the day. Additionally, exercising in the morning enhances sleepiness in the early evening. This helps regulate your circadian rhythm because it makes you sleepy sooner (5). So, if you're trying to go to bed earlier, a morning workout will help.

2. Afternoon exercise


In the afternoon, your body is relatively more efficient. This means that warmed-up muscles and a metabolism that has already been sped up will allow you to run faster and jump higher. You can hop on the treadmill and do interval training or other cardio exercises. You'll feel an increased amount of energy at this time of day.

3. Evening exercise


A morning workout is not the best choice if you're trying to build muscle. In the early evening, your body's ability to gain muscle is optimal (6). Weightlifting and workouts focused on building muscle are best done at the end of the day. However, keep in mind that the later you decide to exercise, the later you will feel sleepy, negatively impacting your circadian rhythm. In conclusion, to support your circadian rhythm, it's best to exercise earlier in the day. However, this does have some limitations, such as lower body capacity and reduced muscle gain.

What type of exercise affects sleep?

Depending on the type of exercise you do, each activity will have a different effect on your circadian rhythm, including the quality of your sleep. We all have our preferences, some of us practice yoga, others run marathons, and others prefer weight lifting. Each of these activities affects our body differently.

Yoga


It is one of the more versatile practices and can be practiced in the morning and evening. The body is stiffer in the morning, but getting it moving helps kick-start digestion and warm-up stagnant muscles and joints. Dynamic morning practice triggers energy to be drawn from fat reserves. The body is less stiff in the evening, and digestion slows down. Evening practice should also be more gentle to avoid stimulating the body too much and help you get to sleep early.

Running or HIIT workouts


Requires proper conditioning, hydration of the joints, and oxygenation of the cells. Morning running can be enjoyable, but many people find more pleasure in running in the afternoon or evening. The later you decide to do this type of exercise, the more severely you will dismiss the feeling of sleepiness, which means moving your circadian rhythm forward. These are the exercises that significantly increase the body temperature and thus reduce the feeling of sleepiness, as the body temperature should naturally fall in the evening. The body needs more than an hour to return to baseline muscle temperature and prepare for sleep (7). If you want to feel sleepy earlier, avoid evening workouts that cause your body to heat up intensely.

Building muscle mass, lifting weights, pilates


These are workouts that, like running, can raise the amount of cortisol, the stress hormone in the body. For this reason, it is better not to do them too close to bedtime. Otherwise, you can easily decrease the feeling of sleepiness, which will shift your circadian rhythm. As a result, sleep will not be as restorative as it should be. It's important to leave an adequate time gap between exercise and bedtime or, if possible, schedule such workouts during the day or early evening.


We hope you'll find this information useful in planning your daily schedule. Rhythmicity is an incredibly important part of our well-being, so don't neglect it in your daily routine.


Get ready and make sure that you choose the best time to exercise and support your natural circadian rhythm! #getready

References:

  1. Irwin M, McClintick J, Costlow C, Fortner M, White J, Gillin JC. Partial night sleep deprivation reduces natural killer and cellular immune responses in humans. FASEB J. 1996 Apr;10(5):643-53. doi: 10.1096/fasebj.10.5.8621064. PMID: 8621064.

  2. Lucassen, E. A., Coomans, C. P., van Putten, M., de Kreij, S. R., van Genugten, J. H., Sutorius, R. P., et al. (2016). Environmental 24-hr cycles are essential for health. Curr. Biol. 26, 1843–1853. doi: 10.1016/j.cub.2016.05.038

  3. Driver HS, Taylor SR. Exercise and sleep. Sleep Med Rev. 2000 Aug;4(4):387-402. doi: 10.1053/smrv.2000.0110. PMID: 12531177.

  4. Iwayama, K., Kawabuchi, R., Nabekura, Y., Kurihara, R., Park, I., Kobayashi, M., Ogata, H., Kayaba, M., Omi, N., Satoh, M., & Tokuyama, K. (2017). Exercise before breakfast increases 24-h fat oxidation in female subjects. PloS one, 12(7), e0180472. https://doi.org/10.1371/journal.pone.0180472

  5. Youngstedt, S.D., Elliott, J.A. and Kripke, D.F. (2019), Human circadian phase–response curves for exercise. J Physiol, 597: 2253-2268. https://doi.org/10.1113/JP276943

  6. A. Shinya, S, Shigenobu. The Role of Circadian Rhythms in Muscular and Osseous Physiology and Their Regulation by Nutrition and Exercise https://www.frontiersin.org/articles/10.3389/fnins.2017.00063/full

  7. Miller DJ, Sargent C, Roach GD, Scanlan AT, Vincent GE, Lastella M. Moderate-intensity exercise performed in the evening does not impair sleep in healthy males. Eur J Sport Sci. 2020 Feb;20(1):80-89. doi: 10.1080/17461391.2019.1611934. Epub 2019 May 9. PMID: 31072


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