Human biology is the result of thousands of years of evolution. The intricate mechanisms on a cellular level help our bodies run on auto-pilot, enabling us to tackle the challenges of the modern way of living. Sleep plays a vital role in our survival. It gives our brain, heart, and organ systems well-deserved rest. Since sleep is so important, evolution didn’t leave anything to chance. It developed a mechanism that controls sleep. The name of this mechanism is the circadian rhythm. Below you can find out what it is, its role, and how to use it to get high-quality rest.

Defining the concept

The name circadian rhythm comes from the Latin phrase “Circa Diem”. It means around a day. It is not something that is reserved for the human species. You can see it in all types of organisms. In humans, it regulates sleep patents, while in flowers, for instance, it tells them when is the best time to open. The best way to understand the circadian rhythm is to look at it as a master internal clock. This master clock is deeply embedded in the brain. Our body uses this clock to tell what is the right time to go to sleep and when is the right time to wake up. You’ve probably experienced the feeling of sleepiness early in the evening and told yourself after yawning: “It’s too early to go to bed, I have a few more things to sort out.” However, it was your body’s natural cue to let you know that now is the perfect time to go to sleep. The circadian rhythm is not constant. It changes throughout our lives. For instance, newborns spend up to 17 hours sleeping each day. As we enter adulthood, our internal clock stabilises and starts managing a more structured sleep/wake cycle.

Is everyone's Circadian Rhythm the same?

“Since it is an internal master clock located in the brain, the circadian rhythm is probably the same for everyone”, you may think. The truth is the opposite. The circadian rhythm is not the same in all people. In some people, the internal clock is set to boost their wakefulness in the morning; others experience wakefulness in the evening. These two groups of people are often referred to as owls and larks (early birds). Owls being the ones who wake up and go to sleep late, and larks who wake up and go to sleep early. If you are an owl, you are an evening person. You will feel significantly more alert in the evening, and staying alert in the morning can prove quite challenging to you. Larks, or early birds, have a differently tuned circadian rhythm. If you are an early bird, you will experience wakefulness in the early morning.

What happens if I don't respect it?

Your busy schedule or the way you currently live your life may not go in line with your natural circadian rhythm. In layman terms, you don’t respect your internal clock. What happens if you continuously ignore the natural cues your body sends you? Two symptoms often tell you that you are not in line with your circadian rhythm - sleepiness and insomnia. If you are an early bird, you can experience sleepiness during the second or night shift. You can experience problems with focus and concentration. Your performance levels and ability to learn new things can also suffer. If you are an owl, you will probably experience sleepiness during the morning shifts and experience the same problems with concentration, focus, performance, and memory. Sleep deprivation is also associated with people who don’t respect their circadian rhythm. It is benign if it happens once in a while, but if it is chronic, it can seriously affect your health. Chronic sleep deprivation affects all systems and can even disrupt your metabolism and weaken your immune system.

How can I use it to get high-quality rest?

Listening to your natural body cues would be the best possible solution to all your sleep-related problems. However, as we’ve established, you can be either an early bird or owl. There is also another factor to consider - your daily schedule, including your work and obligations with your family. A few hacks can help you trick your internal clock and help you to get high-quality rest whether you are an early bird or owl. Expose yourself to natural light as much as possible. As soon as you wake up, open up those curtains and let your eyes bathe in sunlight. Whenever you have the opportunity, go outside to a local park. Generally, aim to spend more time in nature than in front of any screen. Minimise physical activity and dim the lights two hours before you go to bed. Physical activity before sleep is bad news as it can overstimulate you and raise your blood pressure, making it hard to fall asleep. A TV, smartphone, computer, and tablet emit blue light which is part of the natural daylight spectre. The brain interprets it as it is still day and postpones sleep.


The circadian rhythm regulates our sleep/wake cycle. It is regulated by an internal clock located in the brain. Listening to your body cues can help you get well-rested. However, you still have the power to fine-tune it. Bringing subtle changes and sticking to a new routine will help you optimise your circadian rhythm, experience wakefulness when you need it, and live a healthy lifestyle.