Understanding how fitness and sleep patterns are linked to our biological clocks can help us train more effectively and recover faster. Let's take a closer look at circadian sleep rhythms, how exercise affects our biological clocks, and how to adjust your routine so that training and sleep work together.
What are circadian rhythms?
Circadian rhythms are the so-called human biological clock. Over a 24-hour period, they control sleep, wakefulness, body temperature, and hormonal changes. Circadian rhythms allow all bodily processes to adapt to the cycle of day and night. According to research, most of us are most active in the morning—between 8:00 AM and 12:00 PM—and during the day—between 3:00 PM and 6:00 PM. However, circadian rhythms vary from person to person, and some people experience peak productivity at different times. Therefore, it's important to align your work and rest schedule with your biological clock. When your body clock is synchronized, you sleep well and feel energized. However, if your daily routine conflicts with your circadian rhythms, you may experience constant fatigue, sleep problems, and decreased concentration.
How physical activity affects circadian rhythms
Physical activity and the body's biological clock are closely linked. The body's circadian rhythms determine when a person feels most energetic and when they need rest. Regular exercise, in turn, helps regulate the body's biological clock, keeping it in sync with the cycle of day and night. When exercise aligns seamlessly with the body's natural rhythms, it helps regulate various processes, from metabolism to brain function. Properly planning your workouts with your biological rhythms in mind can improve sleep quality, overall well-being, and support the body's natural cycles. For example, at DDX Fitness, an instructor will develop a balanced training and recovery schedule tailored to your daily routine.
When is the best time to exercise?
The best time to exercise is largely an individual matter. You can use your chronotype as a guide here: there are “larks,” “sleepers,” and “owls.” “Larks” are most productive early in the morning, while “owls” are most active later in the day, in the evening or at night. “Sleepers,” on the other hand, are most active in the middle of the day. Despite individual differences, there are general principles that work for most people, regardless of their chronotype. By focusing on these principles, you can develop an effective training regimen.
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Morning workouts help synchronize circadian rhythms with daylight hours and energize. However, it's important to keep in mind that muscles and joints are less flexible in the morning, so it's essential to prioritize a thorough warm-up.
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Daytime workouts can be suitable for high-intensity training and heavy weight lifting. At this time, the body is already fully warmed up, making workouts more effective and reducing the risk of injury.
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Evening workouts can relieve the stress accumulated during the day and prepare you for sleep if you choose the right intensity. They help reduce cortisol levels and smoothly transition to rest. However, intense workouts should be completed at least 2-3 hours before bedtime to allow the nervous system to calm down and the body's temperature and heart rate to return to normal.
What to do if you have sleep and circadian rhythm disorders
If you frequently stay awake at night and sleep during the day, travel, or work shifts, sooner or later it will impact your well-being. When your circadian rhythms are disrupted, you tire more quickly, your concentration decreases, and your health risks increase.
Here's what you need to restore your circadian rhythms:
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light hygiene – bright morning light and subdued evening lighting;
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sleep routine – try to go to bed and wake up at the same time, even on weekends;
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Physical activity – morning and afternoon workouts help to “set” your internal clock, and quiet evening activities improve the quality of sleep;
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Limit screen time—avoid using smartphones, tablets, and computers 1-2 hours before bed. The blue light from screens suppresses the production of melatonin, the sleep hormone;
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Diet: Avoid heavy meals, caffeine, and alcohol before bed. A light dinner 2-3 hours before bed will help your body prepare for recovery.
How to analyze your biological clock
Start keeping an activity diary. For 1-2 weeks, write down:
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bedtime and wake-up time;
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quality of night rest;
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periods of high and low energy throughout the day;
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time and intensity of training;
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nutritional features.
Use modern technology. Fitness trackers and smartwatches can help you monitor key metrics: sleep phases, overall activity, and heart rate variability (HRV)—how the intervals between heartbeats change. The better these intervals adapt to your workload, the greater your body's ability to adapt to stress. This objective information will form the basis for personalized recommendations from a trainer or doctor.
Turn to the experts.
Trust the experts. They will help you take into account your individual needs and create training and recovery plans.