All About the Circadian Rhythm
Circadian rhythm is the body’s internal clock that is responsible for regulating a person’s sleep cycles, alertness, digestive system, hormones and body temperature.
Primarily run by the brain’s suprachiasmatic nucleus (SCN), the Circadian rhythm responds to the amount of light and darkness it receives from the environment.
The Circadian rhythm is disturbed when your eyes are exposed to a lot of artificial light.
It is also negatively affected by irregular schedules where bedtime and wake-up times are not maintained properly.
In this blog, let us learn more about the Circadian rhythm clock.
Things that dominate the Circadian rhythm—
1. Light Exposure- Light is the chief signal that tells the internal clock what to do and keeps the mind & body in-sync with the external environment.
2. Melatonin and Cortisol- Melatonin is a hormone that helps a person fall asleep. Every night, from about 9 PM, the body starts producing melatonin in preparation for sleep.
Every morning at about 7-8 AM, the body starts suppressing melatonin production.
Around the same time, it also starts the production of cortisol. An increase in cortisol helps your mind and body to gain alertness and get ready for the day.
3. The Master Clock- The suprachiasmatic nucleus (SCN), located in the hypothalamus part of the brain has been nicknamed as the Master Clock.
This part of the brain largely governs the Circadian rhythm by receiving light signals and darkness signals from the eyes.
4. Other influences- In addition to the above-mentioned factors, things that influence a person’s Circadian rhythm include physical activity level, food intake, and social interactions.
What happens when circadian rhythms are disrupted?
When the Circadian rhythm is disrupted, the body's internal clock falls out of balance. And with it, a number of other bodily systems fall out of balance as well.
As a result, numerous physical health and mental health issues start to occur.
1. Sleep Disorders- Sleep related health conditions like chronic insomnia, jet lag, excessive daytime sleepiness, shift work disorder, and delayed/advanced sleep phases are seen in people whose Circadian rhythm is not working properly.
2. Mental health issues- People who consistently find it hard to get their required hours of sleep also suffer from some form of mental health conditions.
Those conditions include depression, SAD (seasonal affective disorder), anxiety, bipolar disorder, and schizophrenia.
3. Chronic diseases- Regular disturbances in a sleep schedule often lead to a host of chronic diseases that have an adverse affect on a person’s health.
Those diseases include obesity, type 2 diabetes, neurodegenerative disorders (Alzheimer’s and Parkinson’s), cancer and cardiovascular disease.
How to maintain a healthy Circadian rhythm?
If you want to avoid all the Circadian rhythm disorders, then it is important for you to maintain a healthy Circadian rhythm.
Here’s how you can maintain a healthy Circadian rhythm—
1. Regular exposure to light- Make sure that every morning you soak-in some sunlight.
Though morning time is ideal to get some sunlight, most times during the day is fine for exposure to natural light.
However, it is best to avoid the sun during midday and early afternoon as the sun gets too strong at that time.
2. Adhere to a sleep schedule- It is important for you to go to bed at a specific time every night and wake up at a specific time every morning if you want your sleep-wake cycles to keep running smoothly.
3. Exercise- Engage in some sort of physical activity (walking, jogging, strength training, swimming, yoga etc.) on a regular basis in order to support your Circadian rhythm.
But at the same time, avoid any intense workouts late in the evening.
4. Screen time- Stop looking at screens at least an hour before bedtime.
Blue light from electronic devices (cellphone, tablet, T.V. etc.) hinder the production of melatonin, a hormone which is important for you to fall asleep and stay asleep.
5. Bedtime routine- Prepare your body to go to bed and take rest for the night. In order to do that, create a bedtime routine that you find relaxing.
Your bedtime routine can include anything from washing your face and putting on moisturiser to taking a warm bath and reading a book.
Circadian Rhythm FAQs
What is a normal circadian rhythm?
Humans have a built-in 24-hour biological clock that is crucial for regulating their sleep-wake cycle, metabolism, hormones and body temperature.
This biological clock is known as the circadian rhythm.
It is responsible for keeping a person alert during the day and making her fall asleep and stay asleep during the night.
The circadian rhythm is controlled by the suprachiasmatic nucleus (SCN)— a part of the brain.
It is done mostly by regulating the levels of cortisol and melatonin (on the basis of light-exposure) as and when needed.
What is the 10, 3, 2, 1, 0 rule for sleep?
This rule helps you in enhancing and sticking to a steady sleep-awake routine.
According to the 10, 3, 2, 1, 0 rule, you need to eliminate caffeine 10 hours before sleep, cut off alcohol 3 hours before bed, stop working 2 hours before bed, stop looking at screens 1 hour before bed and hit the snooze button 0 times in the morning.
Why do older people wake up at 3:00 am?
It has been found that older people often wake up around 3 AM due to shifts in their sleep cycles. These shifts have made them stay longer in lighter sleep stages than deemed normal.
The shifts in sleep cycles are mostly caused due to various age-related factors.
The main factors include increased cortisol levels, advanced circadian rhythms (earlier bedtimes), and hormonal changes such as reduced melatonin.
Another major factor is the need to urinate more frequently.
How many hours of sleep should I get each night?
Most adults need to get 7-9 hours of sleep every night.
However, the exact amount of sleep required by a person depends on certain elements such as their activity level, age and the condition of health.
One of the most important factors while trying to get proper sleep is to adhere to a specific sleep schedule.
A person needs to go to bed at night at the same time and wake up at the same time everyday in order to maintain a sleep schedule efficiently.
Which organ controls circadian rhythm?
The prime structure that determines the workings of the circadian rhythm in mammals (including humans) is the suprachiasmatic nucleus (SCN).
The suprachiasmatic nucleus (SCN) is located in the hypothalamus part of the brain. It is considered to be a master clock containing as many as 20,000 nerve cells.
These nerve cells receive direct input from the eyes and help in synchronising various bodily functions within the 24-hour light-dark cycle.
What vitamin deficiency causes you to wake up at 3 AM?
Studies have shown that a Vitamin D deficiency in the body can cause a person to wake up at 3 AM.
Certain health conditions such as diabetes and hyperthyroidism can also lead to circadian rhythm sleep disorders.
These sleep disorders can often leave a person feeling exhausted and sick.
Who sleeps for 90% of the day?
Koalas spend 90% of the day sleeping. That’s 22 hours of sleep in a 24-hour time period. Natives of Australia, Koalas live and hence, feed mainly on eucalyptus trees.
These cute little thickset arboreal marsupials spend about 10% of their day eating and sitting around.
What hormone is released at 3AM?
Scientists have found that the level of the stress hormone, Cortisol, starts increasing between 2 to 3 AM in preparation of your body’s wake-up process.
However, in case you are already stressed about something, or anxious, then the natural rise in cortisol can make you fully awake in an instant.
What does Chinese medicine say about waking up at 3 AM?
In TCM (Traditional Chinese Medicine), when a person wakes up between 1 AM and 3 AM on a regular basis, it means that there is an imbalance in the Liver meridian.
Liver meridian (a key energetic pathway in TCM) is responsible for regulating blood, detoxifying the body and processing the emotions of a person.
When a person is waking up in the above-mentioned hours, it is a sign that that person might be suffering from severe stress, anger and/or frustration.
So much so that it is creating a hindrance in that person’s sleep cycle and preventing her from entering a stage of deep rest.