Circadian Rhythms: Your Questions Answered

Circadian Rhythms: Your Questions Answered

The Ins & Outs of Circadian Rhythms

Kokoon’s mission is all about improving your ability to sleep and relax. Our Nightbuds work to ensure you get an optimal night’s sleep, no matter who you are, where you are or how you live. So, what better way to delve deeper into how to optimise your sleep, by exploring the intricacies of circadian rhythms.

Thanks to our in-house scientific sleep adviser, Nick Witton, we’ve got all the answers to your circadian rhythm questions right here in this article. So, sit back, relax and feel the circadian rhythm.

What are circadian rhythms?

Sleep-wake regulator

Circadian rhythms are 24-hour cycles in which humans experience physical, behavioural and mental changes as they respond to light and dark. It’s also commonly known as the sleep-wake cycle.

Interestingly, it’s not only humans that are affected, but nearly all living things too. In fact, every single organism on the planet, from plants and fungi, to microorganisms, all have a circadian rhythm.

Why do we have circadian rhythms?

Circadian rhythms help organisms time their daily and seasonal activities, so they are synchronised with the outside world.

Are biological clocks the same thing as circadian rhythms?

No, but they are related. Biological clocks produce circadian rhythms and regulate their timing.

How did circadian rhythms come to be?

“There have been over a trillion dawns and dusks since life began 3.8 billion years ago.”(1) (Yikes, bet that’ll make you feel young.)

The earth’s rotation has slowed to just under 24 hours and is now 23 hours, 56 minutes and 4 seconds. And it’s this rotation of the earth that creates the day/night cycle, with the earth's axial tilt at 23.4 degrees, creating the seasons.

What daily changes result from these consistent solar cycles?

These daily changes include:

  • Environmental light.
  • Temperature.
  • Food availability.
  • Predation chances.

Circadian clocks

Biological clocks (also known as circadian clocks) are organisms’ innate biological (natural) timing devices, regulating the cycle of circadian rhythms.

Individual clocks

Every cell in the body has an individual clock. The body clock in the SCN (suprachiasmatic nuclei) in the brain, coordinates the billions of cellular clocks in the organ systems throughout the body.

Light is the main cue the body uses to sync the internal body clock to the outside world. Physiological or behavioral changes do not occur in response to the light/dark cycle, but anticipate the onset of light and darkness by an internal biological clock – the circadian clock.

What’s an example of a light-related circadian rhythm?

  • Sleeping at night and being awake during the day.
  • Eating.
  • Drinking.

Which parts of the body and its functions are affected by the circadian rhythm?

Circadian rhythms can influence important functions in our bodies, such as:

  • Hormone release (from the Pituitary Gland).
  • Metabolism (eating habits and digestion).
  • Body temperature.
  • Sleep-wake cycles.
  • Immune function.
  • Urine production.

What happens in the body during the circadian period?

The body displays an endogenous change in biology.

The body then anticipates light and daytime and so the active phase of the circadian rhythm begins. This is where:

  • High energy is expelled.
  • Food and water are consumed.
  • Stomach, liver, small intestines, pancreas and blood flow are active

The body anticipates darkness and night-time and the inactive phase of the circadian rhythm begins. Here’s what happens:

  • Sleep can occur and is the normal suspension of physical activity.
  • Cellular repair and removal of toxins occur, plus brain, memory and information processing happens.
  • There can be an increase in alertness at night known as the circadian alertness surge.

Does the body make and keep its own circadian rhythms?

Yes, natural factors in your body produce circadian rhythms.

Circadian rhythms and sleep

The body’s circadian rhythms control the sleep-wake cycle. They play a role in sleep due to how the body and brain respond to darkness, which is when most humans feel tired and tend to sleep.

What happens as darkness sets in?

  • The body’s biological clock instructs the cells to prepare the body for sleep.
  • About two hours before your body wants to be asleep, the hormone melatonin starts to rise and facilitates the onset of sleep.
  • The SCN in the brain controls the production of melatonin.
  • Melatonin peaks around 2–4 A.M.
  • Melatonin levels subside by morning, allowing wakefulness.

How does blue light exposure alter circadian rhythms?

Humans are “blue sky detectors” when it comes to modulating melatonin levels.

And unfortunately exposure to light from mobile devices during the night can alter circadian rhythms and sleep-wake cycles. Ultimately leading to an increase in alertness and making it harder to fall asleep.

Make sure you grab a pair of blue-light blocking glasses or switch your gadget off an hour or so before bedtime. Easier said than done - we know.

It’s also vital to remember the importance of getting natural light exposure, so get out into nature as and when you can.

Do circadian rhythms affect body function and health?

Yes. Circadian rhythms can influence:

  • Mood regulation.
  • Hunger.
  • Arousal and wakefulness.
  • Alertness and cognitive function.
  • Physical performance.

Can irregular circadian rhythms affect human health?

Biological clocks that run fast or slow can result in disrupted or abnormal circadian rhythms.

Irregular rhythms have been linked to various chronic health conditions, such as sleep disorders, obesity, diabetes, depression, bipolar disorder and seasonal affective disorder. (2)

If you’re finding it hard to sleep due to external disturbances, grab a pair of Kokoon Nightbuds. They’ll help you to diminish sleep struggles and encourage a more regular circadian rhythm.

What are the effects of eating & sleeping on circadian rhythms?

Eating and sleeping at the wrong times (outside of the master circadian rhythm) can cause distorted cell behaviours.

If you eat at the wrong time, cells will take in nutrients in the digestive tract at the wrong time, resulting in the failure of nutrients being processed correctly.

You may also experience:

  • Disrupted hormone production.
  • Disrupted immune response.
  • An inflammatory response.

Try to avoid snacking after dinner and avoid really heavy night time meals.

Circadian rhythm treatments are used for sleep disorders, obesity, mental health disorders, shift-work disorders and jet lag.

Circadian Rhythms and Jet lag

The most common disruption to circadian rhythms occurs in the form of jet lag.

Jet lag happens when we pass through different time zones, causing our biological clocks to be at odds with the local time.

It’s tricky to know whether to fight through your jet lag or allow yourself some quality napping time. What you can do, however, is try to relax and try taking it easy your first day or two, avoid alcohol and sleeping pills, plus say goodbye to caffeine until you’re naturally buzzing again. Our noise-masking headphones are a great option to help mask noise whilst travelling and unwind.

What's the difference between Chronotypes and Circadian Rhythms?

Your Chronotype is your own personal body clock and refers to your genetic disposition to the circadian clock.

The Sleep Foundation describes how a “chronotype is the natural inclination of your body to sleep at a certain time, or what most people understand as being an early bird versus a night owl”. Chronotypes can help regulate many things, including the time you go to sleep and the time you get up. It can make you feel active and alert at different times during the day and also feel tired and ready to unwind at others.

Can I change my Chronotype?

Due to the genetic nature of your chronotype, Scientists consider it very difficult or impossible to purposely change your chronotype, though it will probably shift throughout the course of your life. However, it is possible to shift and “train” your circadian rhythm by maintaining a regular routine. For example you can set your sleep schedule in the MyKokoon app using the Smart Schedule feature, to help monitor and improve your sleep within the context of your own circadian rhythm.

There is SO much to learn about circadian rhythms, so nailing the basics is a great way to create a foundation of knowledge. By learning what affects your own circadian rhythm and identifying your chronotype, you can work on becoming more aware of your own schedule and habits and how they impact and are impacted by both your circadian rhythm and your chronotype.

Want to optimise your sleep with game-changing tech? Explore our Nightbuds now.

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  2. Reddy S, Reddy V, Sharma S. Physiology, Circadian Rhythm. [Updated 2021 May 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:


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