Before we dive into a detailed understanding of the process and effects of the circadian rhythm, let’s know a little more about what exactly it means and why it exists.
What is circadian rhythm?
‘Circadian’ is derived from the Latin phrase ’circa diem’ that means ‘about a day'. Circadian rhythms are a result of a human body’s internal timekeeping system via a biological clock. They are synchronized with a master clock in the brain and are followed by different systems in the human body. Throughout the 24-hour cycle, the circadian rhythms regulate the productions of several hormones that determine your body’s course of actions and reset themselves every 24 hours.
One of the most important as well as common circadian rhythms is the sleep-wake cycle. Circadian rhythms play a vital role in directing the body to rest and then waking up feeling energetic. This ensures that your body gets a restorative and undisturbed sleep, which indirectly affects the other body parts and functions.
Why is it important?
Circadian rhythms highly influence the sleeping cycle and sleep plays an integral part in maintaining a balanced physical and mental health.
Circadian rhythm is not only responsible for your daily sleep and wakefulness cycle, but also eating, digestion, hormonal activities and other body functions.
The circadian clock consists of over 20,000 neurons, known as the suprachiasmatic nucleus (SCN) that are located at the base of the brain. These neurons react when the first ray of light hits our eyes and are then responsible for signalling the rest of the body the respective actions to be taken. Without these signals, the body will not be able to perceive any orders and will fail in functioning the important body processes.
When the circadian rhythms in a body are well-aligned and on track, they contribute to achieving a consistent, restorative and undisturbed sleep routine. And when this rhythm is thrown off, the sleep cycles are affected the most and sleep-related problems like insomnia, disturbed and scattered sleep, etc. start affecting the body.
How does it work?
Circadian rhythm works by giving the body the required orders to follow and carry out the day to day functions. It ensures that within the 24-hours cycle, the body optimizes all the processes. It not only exists in humans but also works along with almost all other living creatures. Like in plants, the circadian rhythm controls the flowering and photosynthesis processes. And in animals, especially nocturnal animals, it prevents them from setting outside in the daytime and falling prey to predators.
Once the day begins, the body follows the ‘zeitgebers’ (meaning ‘time givers’ or ‘synchronizers’ in German) which are forms of light and other signals that synchronize the circadian rhythm to the day and night cycle.
In the morning when the sun rises, the body produces a hormone that makes us feel fresh and alert, called ‘cortisol’. And as the day proceeds, different body functions make use of the circadian rhythm to carry out different processes. Few examples as follows:
- The urge to pass stools every morning immediately after waking up or having the first glass of water or tea/coffee later
- Feeling refreshed and energetic only after having the first meal before starting the day, i.e. breakfast
- Pangs of hunger that keep appearing at the same intervals every day
- Digestive systems producing proteins/digestive juices as per the body’s eating schedules
How different is it from a biological clock?
Biological clocks regulate all possible bodily functions, and circadian rhythm is one of them. Biological clocks are more adaptive to the environment, where else circadian rhythm follows a strict 24-hour cycle and are adaptive to a daily routine.
For example, plants adjusting to the different seasons and weather conditions, or animals migrating to different locations basis the climatic conditions - these are determined by biological clocks that are way ahead of a 24-hour cycle.
The circadian rhythm and its effects on sleep
The most common circadian rhythm is known to be the sleep-wake cycle and its most often used is in the context of sleep.
The daylight exposure causes the circadian clock to produce cortisol and generate alertness that ends up waking up the body and preparing it to take on the day ahead.
As the sun sets in by the evening, the body slowly reaches the peak of fatigue and the production of melatonin (a sleep-inducing hormone) begins. As it gets darker, melatonin rises and keeps sending signals to sleep throughout the night. This process contributes to giving you a good restorative sleep for about 8-10 hours that helps you wake up energized and alert.
But what happens when the circadian rhythm is thrown off?
In these changing times where the world is moving towards a more unbalanced and unhealthy lifestyle, studies have proven that many people are experiencing a disturbed circadian rhythm.
When the external clock clashes with the body’s internal clock, the circadian rhythm is disturbed and further causes several effects on the human body. It not only affects the sleep cycle but also affects other bodily functions like digestion, energy levels, mental well-being, weight control, etc.
- Hormonal Imbalances
Important changes in the levels of our hormones occur at the night. For instance, melatonin is highest between 11 pm - 5 am, growth hormone is the highest during 1- 4 am at night and cortisol our stress hormone is the lowest around midnight and reaches its highest daily levels when we wake up.
All these hormones affect our metabolic processes. A poor sleep structure can affect the normal secretion of these hormones and thus lead to poor digestion, changes in weight, feeling fatigued and bloated through the day.
2. Weight Gain
Changes in the circadian rhythm such as in shift workers offset the natural eating times and unusual eating behaviours are seen to be associated with an increased prevalence of diabetes, obesity and high blood pressure in these individuals.
The hormone leptin that signals satiety is the highest around 11 pm at night. Any change in your sleep cycle also affects the levels of that hormone.
Insulin sensitivity is also the lowest at night. Hence food consumption during the later hours of the night has greater potential to raise blood sugar and lead to diabetes in the long run.
What are some factors that highly affect the circadian rhythm?
Circadian rhythm can be disrupted over the short or long term. There are several types of circadian rhythm sleep-wake disorders (CRSWD) based on different characters and causes. These result in having difficulty falling asleep at night and can show symptoms like insomnia, sleep loss, tiredness in the morning, depression and increased irritability.
- Advanced Sleep Phase Disorder
People with this disorder get tired quite early and are asleep way before the normal sleeping time and wake up very early. This affects their daily routine and also hampers their social lives. However, this happens rarely and usually is found in middle-aged or older people.
- Delayed Sleep Phase Disorder
We are all familiar with this disorder and have also experienced it at some point of our lives. Just like night owls, people stay up the whole night, only to sleep throughout the morning and wake up late. Even though it affects only 1 or 2 out of 1000, it is known to be quite common in teens.
- Irregular Sleep-Wake Rhythm Disorder
When people do not have a set sleep-wake routine, they end up having naps or sleeping for shorter periods throughout the 24-hours. It is usually connected to conditions associated with the brain, for eg. dementia, trauma etc.
- Jet Lag Disorder
When a person travels through multiple time zones in a very short period of time, especially through flights, they experience jet lag. And when they began settling in a new region with a different day-night cycle, their circadian rhythm takes longer to get accustomed to the new cycle and causes several sleeping problems.
- Shift Work Disorder
When people work night shifts for a long period, their body starts working in a reverse schedule affecting the efficacy of the circadian rhythm. This causes a clash of the rhythm with the daylight hours and affects the sleeping patterns.
Apart from these, the circadian rhythm is also affected by several other physical and mental factors. Like individual behaviours, late working cultures, stress levels, travelling, emotional conditions, etc. And at times it’s very difficult to diagnose or find out the root causes for these.
How to improve and maintain a healthy circadian rhythm?
Circadian rhythm follows the body’s biological clock. Hence it is very important to make efforts that not only train our body but also the brain, in achieving a routine that comprises healthy habits.
1. Seek out the sun – The morning sunlight provides the body with several nutrients and helps in activating the core functions of our body. It makes the mind brighter and restores the required energy and positivity to carry out the day.
2. Have a consistent sleep schedule – Your body’s biological clock and your external clock should be in sync. When you sleep and wake up at the same time, the circadian rhythm gets a clear indication and becomes more efficient with the same routine every day.
3. Work out the body and the brains – Exercise does wonders for your physical and mental health. It aids in releasing ‘endorphins’ also called the happy hormones that elevate your mood and bring emotional stability. Plan your workouts at a time that makes you feel winded down at night. Workouts late into the night can have the opposite effect on some people.
4. Limit unwanted naps – Limit or completely avoid taking naps in the daytime. Afternoon naps can disturb the body’s natural sleep patterns, resulting in staying awake late at nights. If you have to, opt for power naps (approximately 20 minutes long).
5. Improve your sleeping environment – To have a comfortable sleep, one should sleep in a comfortable sleeping environment. Keep your sleeping space free of clutter, dark and clean. Peaceful sleep is a result of a peaceful ambience.
6. Focus on eating protein-rich meals – Especially breakfast needs to be a protein-rich diet that can aid in digestion and produce the required energy throughout the day.
7. Lower stress – Stress affects your body in unimaginable ways. Especially when it comes to sleep, stress can keep you awake for the whole night and keep your mind busy with unwanted thoughts. It reduces the production of the important hormones that facilitate good sleep.
8. Try some sleep-inducing drinks - Consuming turmeric milk or chamomile tea before you sleep, helps in relaxing the body and preparing your mind for a sound sleep. These are also known to cure insomnia in some cases.
9. Limit your caffeine - Try to avoid caffeinated drinks after 4 pm. This includes teas, coffees and sodas. If opting for teas, prefer caffeine-free options.
10. Power down - Once the day comes to an end and you are on your bed, remember to log off completely. Power down both your body and gadgets and focus on your thoughts and let your body slow down as you start falling asleep.
In spite of trying the above-mentioned methods, if you continue to observe symptoms of any of the CRSWDs, consider seeking a specialist's help.
Disclaimer - This information is provided for educational purposes and should not be construed as medical advice. Please consult with your healthcare practitioners before undertaking any changes in your diet or adding supplements.
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