What Is Your Circadian Rhythm? – The Function Of Your Internal Clock

The circadian rhythm or internal biological clock is something that you might of heard of before.

Think of your brain as a machine that can be programmed to perform functions such as going to sleep and waking up nearly at the same time everyday.

If you occasionally have issues going to sleep or have more serious sleep problems, it will be a benefit to understand this natural rhythm which your body follows.

Let us explore what is your circadian rhythm, the function of your internal clock and how this rhythm helps you follow a structured sleep schedule.

what is your circadian rhythm

What Is Your Circadian Rhythm?

The circadian rhythm is a natural biological process that replicates itself every 24 hours. It is derived from two Latin words:

  • circa = around 
  • diem = day

When you combine these two words together they translate to around a day.

An interesting fact about circadian rhythms is that they are not solely exclusive to humans, this biological function also occurs in many plants and other animals as well.

Alarm clock.
Circa Diem!

Functions That Happen At The Same Time Everyday

The most common components of the human circadian rhythm are displayed in this diagram. Take a look and note the times that your body should be performing these functions everyday.

For example, you have the highest alertness around 10AM everyday. In the case that you have a day job, this scheduled alertness will help you stay awake and complete the task at hand.

However, this is a general statement because everybody operates on a different schedule. There are people who work 2nd or 3rd shift times.

There are many elements that impact your sleep patterns. An important element is the hormone known as “melatonin” and the time of the day that your body produces a high or lower quantity of said hormone.

Observe the diagram and you will see that a good number of people will begin to produce melatonin around 9PM at night and that production ends around 7:30AM.

This indicates that if you were to go to sleep after 9PM, you will find that there is a higher probability of falling asleep rather than going to bed prior to 9PM.

Naturally, if you wake up after 7:30AM, you will find that time is easier to wake up to than waking up at dawn. This particular time interval is very close to the natural cycle of daytime and night time in a majority of countries around the world.

In addition, your circadian rhythm is also managed to a certain degree by the cycle of daylight and darkness throughout the course of a day.

The Effects Of Light and Dark

Humans and a large number of animals are biologically programmed to be active during the day and to sleep at night when it is dark. This disposition is referred to as being “diurnal” as opposed to being nocturnal which is sleeping during the day and being active at night.

Daytime scenery.

However, not all of us consistently go to sleep and wake up at the same time everyday. This natural rhythm is different for every person and if that is not monitored, then there is a chance that you might find it difficult to go to sleep or wake up at the time that you designated for yourself.

This structured form of internal body functions explains why some shift workers find that their sleep schedule has been disrupted. This holds true if your shift times change on a regular basis.

Night time scenery.

An example of the variations in our rhythm patterns is often noticed in teenagers. There is research that shows that the internal biological clocks in teenagers are shifted to a later time more so than that of children and adults.

This later shift in a teenager’s biological clock can have a notable impact on their ability to wake up early and concentrate on their academic work in the morning.

The Functions Of The Circadian Rhythm

The majority of people do not discuss much about the circadian rhythm in everyday conversations. However, we do speak about another part that plays an essential role in controlling the circadian rhythm and that is our “internal clock”.

The internal clock is a very small portion of the brain that is called the suprachiasmatic nucleus.

How Light And The Internal Clock Function Together

When your eyes observe light, there are signals that move from the eyes through optic nerves and end at the suprachiasmatic nucleus. From that point the suprachiasmatic nucleus sends its own signals to different portions of the brain.

This diagram shows where the suprachiasmatic nucleus is located

One of the areas that is affected is the pineal gland. Once the signal reaches the pineal gland it stops the production of melatonin. Once the levels of melatonin are decreased, you will being to feel more alert.

The opposite effect happens once it begins to get darker in the evening. The internal clock will at this point signal the brain to produce a higher level of melatonin, which in turn will help you feel more relaxed and prepare you for sleep.

You can think of your body’s internal clock as a light switch in a room. When the light switch is turned on you will be active and working in the same way that electricity is flowing from the outlet through the electrical cord and then into the lamp.

Our brains work in the same way when sending signals through the many nerve highways in the body.

When the light switch is turned off, you will begin to power down, feel relaxed, and then fall asleep.


What Are Zeitgebers?

Zeitgebers are the influence that light has on your internal body clock. These zeitgebers are external factors that impact your circadian rhythm.

Think of it as your body having its very own built in clock. However, external factors such as light are needed in order for this clock to function properly.

Times When Your Body Clock Has Been Disrupted

The circadian rhythm in your body is very sensitive and can be disrupted rather easily. Factors such as changes in the amount of daylight you receive everyday or the decisions that you have made towards your daily schedule can impact the level of alertness and sleepiness that you feel throughout the day.

These are some circumstances and sleep disorders that correspond with the body clock being disrupted such as:

Usage Of Electronic Devices

There is evidence that using electronic devices such as smartphones and laptops close to a scheduled bedtime can disrupt your internal body clock and affect how you sleep at night.

It is best that do not use any electronic devices later in the evening. Anything that you are currently doing at that time will be there in the morning, it is not worth losing sleep over.

Jet Lag and Shift Work

A good number of people have temporary issues because of jet lag or working abnormal shift times. These issues can be a challenge to manage in some fields.

An example of jobs that experience jet lag and shift work are flight attendants and airplane pilots who regularly travel to different time zones and have to adjust to them.

This flight attendant shares his experience with jet lag:

Delayed Sleep Phase Syndrome

Some people have a sleep disorder known as “delayed sleep phase syndrome”. This sleep disorder causes a person to sleep at a later time than normal. This is often seen more in teenagers and results in others labeling them as lazy.

Seasonal Affective Disorder

During the winter months of the year, some people will discover that their mood can be influenced due to the shorter days that have less sunlight. If the disorder is serious enough then it is referred to as “seasonal affective disorder”.

This disorder can affect a person’s mental health by making them feel “blue” along with other symptoms that resemble depression.

Winter scenery.
Also known as the “winter blues”.

How You Can Apply This Information

Your body has its own natural way of helping you go to sleep at night by creating its own supply of melatonin. This hormone also reduces your body’s temperature in order to further prepare you for sleep.

At this point, you should have a good grasp on how the internal body clock functions. The important action to take now is to help rather than struggle with the issue at hand. These are suggestions that you should consider:

  1. If you work shifts that have times that change frequently or have issues with traveling and jet lag. The good news is that you can reset your internal clock. Nevertheless, it is not always the best decision to travel on a plane when there is daylight present. This will vary based on where you travel and the number of time zones that you have traversed over.
  2. You can also utilize the information from your internal clock to adhere to the sequence of day and night as close as you can. However, if you live in a part of the world where there are exceptionally long days or nights then this can be prove to be challenging. It is still worth an attempt to sleep after 9PM and to wake up at 7:30AM or later.
  3. Even though exercise can aid in getting a good night’s sleep, however an intense workout session prior to your bedtime is not the best course of action as this can keep you awake.
  4. Consuming large meals prior to your bedtime can increase your body’s temperature and this will hinder the natural cycle of temperature reduction that prepares you for sleep.
  5. It will help you out greatly if you make an attempt to go to sleep and wake up at the same time everyday as this is one the best methods to resetting your clock because this action helps it maintain a consistent pattern.

Final Thoughts

Your circadian rhythm or internal clock plays a very important role in your life. It helps manages the time you go to sleep and the time that you wake up. Not only is sleeping and waking up at the same time everyday good for you, it also helps you maintain structure in your everyday life.

From my own experience, I have struggled to maintain a consistent sleep schedule in the past. However, I have followed the guidelines in this article and now I am able to sleep and wake up at a consistent time everyday.

After all, having a disrupted sleep pattern can lead to low energy levels and not being able to perform at your best throughout the day. You do not want to feel sleepy at a time when you should feel be feeling energized. That feeling of being energized will help you seize the day.

Seize the day.

Has your biological clock been disrupted by shift work and other factors?

What are your thoughts on this subject?

Please share your thoughts in the comments section below.

Photo Credit: Pexels, Pixabay and Unsplash

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4 Comments on “What Is Your Circadian Rhythm? – The Function Of Your Internal Clock”

  1. Hello Stefan,

    That is great that you follow a consistent pattern. Doing so benefits your overall health in the long run. Yes, since electronics have become a such a big part of our modern society. Most people use them all the way up until the time that they go to sleep. I witnessed others lose out on a lot of precious sleep because they were preoccupied with other things. I recommend for the last hour of each day that you turn off all electronic devices. This will help both you and your wife sleep better at night. 

    Best regards,
    Kenny Tang

  2. Hello Babsie,

    That is excellent that you invested in a sleep mask and I agree sleep masks are very helpful to darkening your environment. You have made a very good choice because our brains are conditioned to go to sleep when it is dark and to be active when we are awake. Shift work can definitely change one’s sleep schedule.

    Best regards,
    Kenny Tang

  3. Great information that one should read once in a while.

    I normally have a quite good working body clock. It does fall out of rhythm on weekends when I sleep over and change the ritual for relaxation.

    I did not know that electronic devices near the bed before sleep can have a bad effect. I have to look into that. I have the habit of listening to audio books before going to sleep and mostly fall asleep without turning them off.

    My wife complains about this ritual. She says she cannot sleep well when someone is talking all the time.

  4. I really do realize the light and dark thing when it comes to sleep. I started working later into the evenings and sleep later in the mornings. I had to get an eye mask to cover my eyes to shield them from the morning light.  What a difference that made in my ability to stay asleep in the morning and not toss/turn.

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