What Is Circadian Rhythm? How Do Disruptions Affect You And Your Sleep?

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Your circadian rhythm is part of your body’s internal clock and works in the background to manage many essential processes. One of the major functions of the circadian rhythm is regulating your sleep-wake cycle over a 24 hour period.

Your circadian rhythm is synced with your body’s master clock and dictates the functions of many of your body’s systems. Your body’s clock is heavily influenced by the the environment around you, particularly light, so your circadian rhythm relies on the changing of light between night and day.

A circadian rhythm that is in proper alignment can promote restorative sleep by encouraging your body to get consistent, high-quality sleep which has huge benefits to our health and waking life.

In contrast, when circadian rhythms are disrupted, it can lead to sleep disorders and affect other aspects of your physical and mental health.

So, let’s dive in.

We hope we can help inform you on how to sleep better, and improve your overall health and life in the long-run.

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11/21/2023 04:59 pm GMT

How does circadian rhythm work?

Circadian rhythms optimize your body’s processes at certain times across a 24 hour time period. The word circadian comes from the term ‘circa diem’ which is Latin for ‘around a day’. And rhythm can also be thought of as a flow, or a pattern. So your circadian rhythm is like your body’s pattern throughout the day or your body’s natural daily flow.

It’s not only humans that have a circadian rhythm, there are many organisms that rely on an internal body clock to regulate their behaviour. Nocturnal animals for example, use a circadian rhythm to remind themselves to hide in their shelter during the day and away from predators.

For humans, your circadian rhythm is linked to your master body clock which is located in the brain. For those that want to get technical, it’s called the suprachiasmatic nucleus (SCN) and is found in the hypothalamus.

At certain times of the day, the SCN sends signals to other parts of the body to control different physiological activities. The SCN is highly sensitive to light, so any external cues will influence the these signals that are sent around the body. This is why circadian rhythms are so closely linked to the natural day and night cycle.

It’s not just light that the SCN is sensitive to. It can also be influenced by exercise, social activity, and temperature, however, none have quite the effect on circadian rhythms that light does.

how does circadian rhythm work?

Is Circadian rhythm the same as a biological clock?

Circadian rhythms are an affect of the biological clock. Your biological clock can be thought of as a master clock that regulates many bodily processes, the circadian rhythm being one of them.

Plants use a biological clock to adjust to changing seasons, which is different to a circadian rhythm that only works on a 24 hour cycle.

Plants have a biological clock that tells them when the seasons change

How does Circadian rhythm affect sleep?

Circadian rhythms are often spoken about when topics of sleep are discussed. This is because the sleep-wake cycle is one of the core functions of the circadian rhythm, we often measure it on a 24 hour day.

During the day, light causes our SCN, our internal clock, to send signals to our body that promote alertness and focus. This is how we stay awake during the day.

When the sun sets and it becomes dark, our master clock instructs the body to produce melatonin, which is a hormone that encourages sleep and ensure we stay asleep throughout the night.

Our circadian clock keeps our body on schedule so that we sleep during the night to increase our restorative sleep while increasing our activeness and alertness during the day, ensuring you are in sync for the total 24 hours in a day. When we break that 24 hours and impact our rhythm, that’s when things can go wrong.

Does Circadian Rhythm have other functions aside from sleep?

The most well-known function of the circadian rhythm is controlling the sleep wake cycle, however, recent research has uncovered a lot of new information that has enabled us to understand the circadian rhythm on a deeper level.

There have been findings that link the circadian rhythm to mental illnesses including depression, bipolar disorder and dementia.

Research has also found that our circadian rhythm is linked to metabolism and weight as it assists with the regulation of blood sugar levels and cholesterol.

Circadian rhythm research has also shown that it may play a role in preventing cancer. Although the research is still in its infancy, researchers are seeing that the circadian rhythm affects the effectiveness of anti-cancer drugs and believe that our internal clock may influence cancer-killing medications.

What happens when you experience circadian rhythm disruptions?

When you experience disruptions in your circadian rhythm, it causes many of your body’s systems to function incorrectly which can cause serious sleep disorders, leading to more serious health problems.

When your circadian rhythm is off you may struggle to fall asleep, or find yourself waking up during the night, or you may not be able to sleep for as long as you would like or need and possibly may lead to a sleep disorder.

And for the hours that you do get to sleep, the quality of that sleep may be lower.

There are significant consequences of a disrupted circadian rhythm which include an increased risk of insomnia, daytime sleepiness and other sleep disorders.

Studies have also identified circadian rhythm disturbances as a possible contributing factor to obstructive sleeping apnea.

Interruptions to your sleep can cause cognitive problems such as decreased concentration, attention, motor skill and memory. The resulting symptoms may lead to workplace mistakes, lack of efficiency or even accidents.

there are significant consequences of a disrupted circadian rhythm which include an increased risk of insomnia, daytime sleepiness and other sleep disorders

Circadian Rhythm Disorders

Circadian rhythm disorders occur when our body’s internal clock is not aligned with our environment. This can cause many sleep disorders and other health problems which may need treatment.


Insomnia is a common sleep disorder that can prevent you from falling asleep, makes it hard to stay asleep and can cause you to wake up too early and not be able to get back to sleep.

Although you may still feel tired, you might not be able to get back to sleep.

The lack of sleep and quality of sleep can lead to a reduction in energy level, mood and health which can lead to poor work performance and quality of life.

Mood Disorders

A lack of sleep can quickly lead to mood disorders that cause your emotional state to be misaligned with your current situation. You may feel sad or irritable, or you may have episodes of extreme happiness (mania).

Mental Health problems

It can sometimes be hard t0 distinguish mood disorders from other mental health issues because they often come hand-in-hand.

Increased levels of feelings of sadness or emptiness can be linked to depression, while extreme swings of happiness can be a sign of bipolar disorder.

Other health problems

Circadian rhythm disorders don’t always contribute to just a sleep disorder. It can also affect other aspects of our waking life and health including weight, reduced ability for muscle recovery after exercise that can lead to injuries, which may need lengthy treatment to correct.

What can disrupt Circadian rhythms?

The causes of circadian rhythm disorders are varied and could be caused by individual circumstances such as travel or work schedules. However, circadian rhythm disorders may also stem from deeper issues including your genes, or even unknown causes.

the causes of circadian rhythm disorders are varied and could be caused by individual circumstances such as travel or work schedules

Jet lag disorder

Jet lag is a common symptom of people who travel across multiple time zones. You may have experienced this in the past when you take a plane to another country.

When you arrive in new time zones, it can take some time before your internal clock lines up its sleep wake cycle with the new day-night cycle.


This is another common factor that can mess with your sleep wake rhythm.

Caffeine is the primary offender that can interrupt your natural sleep patterns. The most common sources of caffeine are found in coffee, black tea, green tea, coca cola and chocolate among other foods and drinks.

Reducing exposure to these before you go to bed can greatly increase your sleep quality and the number of hours sleep you get during the night.

Shift Work disorder

Work responsibilities and schedules play a large role in the disruption of your sleep and wake cycles.

Shift work requires people to work through the night and sleep during the day which causes the light and dark signals to be sent at opposing times of your natural circadian rhythm.

Video Games

Staying up late playing video games can prevent you from falling into your correct circadian rhythm because of the increased exposure to blue light and high brain activity required to concentrate on the games.

How to support a healthy Circadian rhythm?

There are lots of simple things you can do to help support your circadian rhythm.

exercise, sunlight, sleep routines and a healthy diet are good ways to support your circadian rhythm

Get Some Sun.

By seeking out the sun or natural light first thing in the morning sends a strong signal to your brain that it is daytime.


Staying active throughout the day keeps your brain and body alert and burns extra energy that will make it easier to fall asleep at night. After about 30-90 minutes after exercise the core body temperature begins to drop, helping to regulate optimal sleeping core body temperature.

Avoid Stimulants

This is a big one, and one that can greatly improve your sleep. Avoiding foods and drinks that contain caffeine before bed can help you sleep better at night.

Reduce light at night

As the sun goes down, you body will naturally become sleepy, however, if you leave lights on around the house, watch TV or look at your phone for prolonged periods of time, they continue to send light signals to your brain and may cause you to feel awake.

Limiting your exposure to light at the end of the day can help you feel more ready for bed.

Sleep Wake Cycle

It’s easier said than done, but it’s important to follow a strict sleep wake cycle. This means going to bed at the same time every night and waking up at the same time everyday.

Your body will eventually fall into this pattern, increasing melatonin production at night and you will find it much easier to fall asleep when you go to bed.


Circadian rhythms play an integral role in our overall health and is a corner stone of sleep medicine, and by maintaining good sleep habits we can improve the length and quality of your sleep which can have enormous benefits and avoid disruption in our waking lives.

If you are having sleep issues or a sleep disorder, we encourage you to see your doctor or sleep medicine specialist for advice, diagnosis or treatment. They can help you target the cause and provide you with a plan to help you with your sleep habits.