Nature is full of rhythms. Day and night. The seasons. The ocean tides. Planetary movements. The lunar cycle. The song of a bird. The beating of your heart. Everything around us and within us follows a rhythm that keeps the natural world in balance and togetherness. While there exists a larger, universal rhythm that threads through all the natural entities of the universe, every entity on its own has a natural rhythm it has to adhere to. For example, the moon follows a cycle where it waxes and wanes over a period of 29.5 days. Plants follow the sun’s movement over a day to maximize photosynthesis and even follow rhythmic patterns of blooming. Crabs that live by the shore, adjust their living patterns based on the ocean tides. 

Similarly, humans also have a biorhythm to follow, called the circadian rhythm. The circadian rhythm is the most significant biorhythm for all living organisms and sets the pace for biological processes to happen at regular intervals. 

What is the Circadian Rhythm? 

The word ‘circadian’ is derived from the Latin phrase ‘circa diem’ meaning ‘around the day’. Circadian rhythms are 24-hour cycles that are part of the body’s internal clock that runs in the background, enabling essential biological functions and processes. Different systems of the body follow different circadian rhythms, which means your body has multiple circadian rhythms that are all then synchronized with an internal clock in the brain. A very well-known circadian rhythm is the sleep-wake cycle that governs the states of sleep and wakefulness. Another example is the rhythmic changes in your body temperature over a 24-hour cycle. Factors such as light, darkness, colors, and other environmental factors can influence circadian rhythms. Circadian rhythms enable the brain to receive signals based on the environment and aid in the production of certain hormones, regulate your metabolism, and allow for the seamless functioning of certain biological processes. For example, circadian rhythm ensures that your digestive system produces digestive juices to match the typical timing of your meals. 

Circadian rhythms across the body are connected to the internal clock found in the suprachiasmatic nucleus (SCN) located in the hypothalamus of the brain. The SCN acts as the central pacemaker of the body’s circadian timing system and regulates most circadian rhythms in the body. While light affects the SCN to a great extent, other factors like temperature, social activity, and exercise can also impact the SCN thus influencing the circadian rhythms. [1]

As mentioned earlier, circadian rhythms are present in different systems of the body and play a role in the overall optimal functioning of your body. The most prominent circadian rhythm is the sleep-wake cycle and is perhaps the most studied as well. The SCN is receptive to signals of light and darkness. When morning light sets in, the optic nerves in your eyes send signals to the SCN which in turn triggers the release of cortisol and other hormones to help you wake up. When darkness sets in, the SCN sends signals to the pineal gland which triggers the release of melatonin which makes you feel sleepy and hit the sack. In this manner, the circadian rhythm aligns wakefulness and sleep with day and night and creates a cycle of stability and restorative rest that enables you to stay active during the day. [2]

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What happens when the Circadian rhythm is disrupted?

When the Circadian Rhythm is disrupted, the optimal functioning of the body is disrupted as well. A disrupted sleep-wake cycle can 

1. Dysregulate your sleep pattern
2. Make it difficult for you to fall asleep at night
3. Wake up too many times during your sleep
4. Reduced overall quality of sleep
5. Increased risk of insomnia
6. Excessive daytime sleepiness

Recent studies have also identified disrupted sleep-wake cycles are potential contributors to obstructive sleep apnea (OSA), a sleep disorder marked by repeated lapses in breathing. OSA reduces the body’s oxygen levels and causes numerous sleep interruptions throughout the night. [3], [4]

In short, when circadian rhythms are disrupted, there are significant consequences to your overall health and productivity. 

Causes of Circadian Rhythm Disruption

Circadian rhythms can be disrupted by singular/multiple events on a prolonged basis. Some of the commonly observed causes of circadian rhythm disruption are as follows: - 

1. Lack of exposure to natural light during the day
2. Excessive consumption of caffeine
3. Excessive consumption of alcohol, substances, etc.
4. Frequent air travel
5. Unhealthy lifestyle habits such as staying up late, exposure to artificial light at night regularly, etc.
6. Eating at odd times every day
7. Age
8. Working during the night or late into the night

`Maintaining a healthy circadian rhythm

Having established the importance of the circadian rhythm, here are some ways to restore and maintain a healthy circadian rhythm. [5]

• Stick to a sleeping schedule. Try going to bed and waking up at the same time every day. Having a consistent time to go to sleep and wake up helps maintain a structured routine and will help you sleep better. Better sleep helps you get all the rest and recuperation your body needs as well.
• Make sure to get some sunlight upon waking up, particularly within the first hour of waking up. This helps to fine-tune your internal clock and sets the pace for your circadian rhythm, and promotes alertness. On sunny days, about 5-10 minutes of exposure on waking up is enough, whereas on cloudy, overcast days you may want to spend at least 15-20 minutes outdoors on waking up, as there is enough sunlight to trigger positive effects. 
• Get some movement and exercise every day preferably around the same time. Avoid being sedentary for extended periods of time. Move and shift your body for a few minutes every ninety minutes to keep yourself active. Exercise has a very good effect on your circadian rhythm and can impact your sleep-wake cycle as well. Exercising in the mornings in particular has a positive impact on your circadian rhythm, especially if it’s misaligned.
• Try eating your meals at the same time every day, especially breakfast. Your breakfast time acts as a cue to the body to a) kickstart your digestive system for the day b) ensure seamless digestion through the day and c) calibrate your biological clock aiding in quality sleep
• Avoid using devices like laptops, phones, etc. for at least an hour before you go to bed. Exposure to light suppresses the production of melatonin, so low exposure to light really helps with the natural production of melatonin enabling better sleep quality.

Bottomline, your circadian rhythm is fundamental to your body’s natural way of operating on its 24-hour body clock, thus adhering to its natural rhythm. Maintaining a healthy, active lifestyle in tandem with regular routines can help you maintain your circadian rhythm enabling better health.

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References

1. https://www.ncbi.nlm.nih.gov/books/NBK519507/
2. https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx#:~:text=Circadian%20rhythms%20are%20physical%2C%20mental,a%20light%2Drelated%20circadian%20rhythm
3. https://pubmed.ncbi.nlm.nih.gov/28977444/
4. https://pubmed.ncbi.nlm.nih.gov/26039970/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7185226

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