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You may imagine your body clock works to wake you up at the same time each day. True, many people can set their body clocks to wake at a specific time, with a bit of practice that is! However, there’s a lot more to the body clock and circadian rhythm than that. In fact, the body clock and circadian rhythm pretty much determine the quality of your sleep. That means that if your body clock is out of sync, you may suffer sleep disturbances. But there are ways to reset your circadian rhythm. In this article, we take an in-depth look at the body clock and circadian rhythm, providing a definition and outlining their function and role. Furthermore, you’ll find out about body clock irregularities and how to reset your circadian rhythm to get a better night’s sleep. All in all, you’ll get a detailed insight into all aspects of your body clock and circadian rhythm. Their impact on your overall health is significant, so read on and learn more!

What Is Your Body Clock?
Even though you’ll find the term body clock and circadian rhythm used interchangeably, they are linked but not exactly the same thing. In essence, your body clock sets your circadian rhythm, and nearly each and every cell has a biological clock. All these biological clocks are controlled and synchronized by a master clock in the brain, which also creates your circadian rhythm.

What Is Your Circadian Rhythm?
Your body’s circadian rhythm regulates changes in the body throughout the day. Included here are physical, behavioral, and mental changes. In addition, it determines when you feel sleepy and when you’re fully awake. Over a 24-hour period, your circadian rhythm decides whether you should sleep or be awake. Much like an internal timekeeper, your circadian rhythm regulates periods of rest and activity.


But where is the control center of your circadian rhythm? Well, the master clock in your brain controls it. Light and darkness work to influence the circadian rhythm. When darkness sets in, your circadian rhythm goes on to signal your body that it’s time for rest. Throughout the day, your circadian rhythm raises and lowers your levels of wakefulness. For that reason, you may feel like having an afternoon nap. What’s more, each person’s circadian rhythm is different, hence some people are night owls while others are early birds. Let’s take a look at why:
The Circadian Rhythm of an Early Bird - In early birds, the circadian rhythm is shorter, so they fall asleep earlier and tend to wake earlier too. To be clear we are talking about circadian rhythm in humans not birds.
The Circadian Rhythm of a Night Owl - In contrast, the circadian rhythm of a night owl is longer, so night owls tend to go to bed and wake later.
The Circadian Rhythm Changes with Age - As you know, young children tend to be early birds who then tend to turn into night owls during their teenage years. This is due to a change in body clock activity. In addition, the circadian rhythm changes as we age. Elderly people tend to wake earlier and be more productive in the morning, as one study has indicated.
The Circadian Rhythm Is Subject to Genetics - People don’t choose to be early birds or night owls. In fact, your body clock also depends on your genes. Scientists have studied this area and discovered that your body clock is strongly determined by your genetic profile.

Why Are Your Body Clock and Circadian Rhythm Important?
Apart from being a major contributor to your sleeping patterns, your circadian rhythm also has a bearing on many other health aspects. Important bodily functions such as eating habits, digestion, hormone release, and temperature changes are influenced by the circadian rhythm.

What hormone controls circadian rhythm?
Melatonin is the hormone that the body produces to regualate your sleep cycle. This is why many people take melatonin suppliments to help control their sleep schedule. If your circadian rhythm suffers a serious, prolonged disruption, you may develop health issues including obesity, depression, bipolar disorder, diabetes, insomnia, or seasonal affective disorder.

What Sets the Body Clock/Circadian Rhythm?

To a large degree, the master clock in your brain sets your circadian rhythm. However, outside factors also come into play. As mentioned above, light and darkness have a strong bearing on your circadian rhythm. This means that if you change your exposure times to darkness and light, your circadian rhythm will also change, which is significant, especially if you change from working during the day to working nightshifts.

Your Brain, Melatonin, and Circadian Rhythm

So, what precisely happens in your brain when it comes to your circadian rhythm? And how does light come into the equation? Well, as darkness falls, the pineal gland in your brain produces melatonin when the retina in your eye detects fading light. As time goes on, melatonin levels rise, peaking in the middle of the night for a healthy individual. It’s the melatonin levels that influence your circadian rhythm, which then sets your levels of wakefulness. During the night melatonin levels drop so that by morning, you wake up fully rested. In addition, your melatonin levels also work to reduce your body temperature and brain activity throughout the night. Furthermore, melatonin puts off the production of cortisol, which is responsible for raising blood sugar levels and blood pressure. So, as melatonin levels rise with darkness, the body gets prepared to rest through the night, and essentially, that’s what the circadian rhythm is all about.

Circadian Rhythm Disorders

A variety of factors can throw the circadian rhythm out of sync, as a result of which circadian rhythm disorders occur. In many cases, these circadian rhythm disorders can lead to sleep disturbances and result in health issues.

Circadian Rhythm Disorder Causes

Because the circadian rhythm is influenced by light and darkness, changes in routine or exposure to light can cause circadian rhythm disorders. In addition, other health issues can throw your circadian rhythm off course. Here are the most common causes:
- Starting Shiftwork: If you take on a night job, the times you’re exposed to light shorten. As a result, your circadian rhythm will change and so will the melatonin levels in your brain that contribute to setting your wake-sleep patterns.
- You Change Time Zone: If you move to the other side of the world, your circadian rhythm is going to adjust to the new light-darkness rhythm of your new location.
- Jetlag: Flying into a different time zone will also disturb your circadian rhythm.
- Pregnancy: Scientists have discovered changing circadian rhythms during pregnancy. This should come as no surprise, seeing as so many hormonal changes take place during it.
- Mental Illness and Dementia: Circadian rhythms may also change in people suffering from mental illness. What’s more, scientists have pointed out that maintaining regular circadian rhythms could benefit people with mental health issues.
- Medication: Certain classes of drug are also believed to disrupt the circadian rhythm and cause insomnia.

Best-Known Circadian Rhythm Disorders
Most circadian rhythm disorders are linked to sleep. Here’s a list of the most common:
- Rapid Time Zone Change Syndrome
: If you’ve had jetlag, then you know what this disorder is. Individuals feel sleepy and struggle to be alert after flying from one time zone to another.
- Shift Work Sleep Disorder
: The circadian rhythm in people who take on shiftwork is also likely to get disrupted. This is because the normal day/night cycle does not correspond to the shift workers’ routine, but the body still adheres to it.
- DSPS (Delayed Sleep Phase Syndrome):
People suffering from DSPS have difficulty falling asleep and waking in time the next day.
- ASPD (Advanced Sleep Phase Syndrome):
The opposite is true for people suffering from ASPD. Here, the individual falls asleep as early as 5pm only to wake up between 1am and 3am. This makes it very difficult to maintain a normal work/rest routine.
- Non-24-Hour Sleep-Wake Disorder
: People who are totally blind can suffer from non-24-hour sleep-wake disorder. Because they cannot see any light, the circadian rhythm is disrupted, resulting in irregular sleeping patterns and the consequent fatigue.

Trouble with sleeping is the common symptom of these circadian rhythm disorders. So what treatments are available?

Circadian Rhythm Disorder Treatments

The treatment type depends on the individual’s specific disorder, its causes, as well as lifestyle requirements. If you think you may be suffering from a circadian rhythm disorder, seek medical help. Even though the effectiveness of treatments is not guaranteed, many circadian rhythm disorder treatments can go a long way toward making the condition more manageable. Physicians would arrive at a treatment that enables the individual to maintain his schedule, i.e. to facilitate shiftwork, for instance. Treatments include sleep hygiene techniques, medication, light therapy, dark therapy, and chronotherapy, along with some lesser known treatments. Let’s look at what each treatment type involves:

Sleep Hygiene Techniques

Sleep hygiene techniques are about developing a good sleeping routine and setting up your bedroom for restful sleep. Combined, they can go a long way toward maintaining a regular circadian rhythm. The following tips apply here:

  • Set up your bedroom to be quiet and dark. If you are very sensitive to light, get blackout blinds.
  • Reserve your bedroom for sleeping and sex only
  • Leave screens outside your bedroom door
  • Don’t nap in the evening
  • Stop consuming caffeine drinks at noon
  • Don’t eat late or heavy meals in the evening
  • Don’t exercise later than 3 hours before you want to sleep
  • Establish a sustainable bedtime routine. Go to bed and get up at approximately the same time each day
  • Keep your stress levels in check. If you’re worrying about issues, incorporate meditation or mindfulness exercises into your bedtime routine
  • Avoid drinking alcohol at night. While alcohol may first help you to get to sleep, the quality of sleep later in the night tends to be poor after alcohol consumption
  • Avoid drinking large quantities of any drink prior to going to bed
  • If you work at night, try to set up your bedroom in such a way that it resembles a normal nighttime setting.


By adopting a good sleep hygiene, your circadian rhythm is less likely to get disrupted.

Light Therapy

Light therapy works very well for many people suffering from circadian rhythm disorder. You can either go outside and get exposure to direct sunlight or use specially designed light bulbs for this treatment. Check out the facts with your physician before purchasing one of these special light bulbs. The idea is to sit in front of one of these lights approximately one hour before you need to get up. Alternatively, you can also use it straight after waking up. Specially designed for this treatment or the treatment of seasonal affective disorder, these light bulbs give off approximately 10,000lux. For best results, expose yourself to this light for 1½ to 2 hours each day. The benefits of light therapy are significant for some and insignificant for others. In addition, some experience side effects including migraine, hyperactivity after exposure, or eye puffiness/pain. Reducing the exposure time may help to lessen the side effects. It’s also important to ensure that the bulbs you use filter out the ultraviolet lights. During use, the light needs to reach your eyes, however, you don’t need to look straight at it. If you’re considering trying out light therapy, discuss light strength, exposure length and timing with a professional beforehand.

Dark Therapy

Those with light sensitivity can have their circadian rhythm disrupted by blue light, which has the highest suppression effect of all lights on melatonin secretion at night. TV, smartphone and computer screens emit blue light. This means that watching TV before going to bed as well as sitting in front of a computer or smartphone can disrupt the circadian rhythm that would begin to induce sleep. To filter out this blue light, many people wear special blue-blocking glasses. Alternatively, special screens set up in front of your chosen screen can also filter out this blue light. Light-sensitive people may also benefit from dimming their light in the evening or by purchasing blue light-free bulbs.


Chronotherapy can be effective but requires time and patience. Here, the aim is to achieve the desired bedtime over the course of a few days. Let’s assume you go to bed at midnight but would like to establish a routine of settling down for the night at 10pm. In chronotherapy, you would delay your bedtime by 3 hours each day until you’ve reach your desired bedtime. This means going to bed at 3am the first day, at 6am the second day, and so on. As you can imagine, this process is disruptive and may not be feasible if you’re working. Chronotherapy works the other way round if you would like to delay your bedtime. Let’s assume you are exhausted and want to go to bed at 6pm every day. Start by going to bed a 3pm on the first day and then continue by going to bed at noon on the second day. Keep bringing your bedtime forward by three hours each day, until you reach your target bedtime. Again, this method is disruptive but beneficial for many.
If you choose chronotherapy, you will have to stick to your set bedtime without fail, once you’ve reached your desired time. Any change can upset your newly-set circadian rhythm again, meaning that you’ll have to start from scratch.
Sleep experts approach chronotherapy with extreme caution as it may cause further circadian rhythm disorders. Therefore, it is crucial to discuss all aspects with your doctor and embark on this process under medical supervision.


Circadian rhythm disorder sufferers may also benefit from taking medication, including melatonin, stimulants, and sleeping pills. After looking at the specifics of each case, physicians choose the most suitable type of medication. Let’s look at each in a little more detail:
Melatonin: As we learned earlier, the pineal gland produces melatonin in the brain to induce sleep. Individuals with disrupted circadian rhythms may benefit from taking synthetically produced melatonin supplements. Timing and dosage needs to be set by your physician to ensure this process works.
Stimulants: Your doctor may also prescribe stimulants to heighten your daytime wakefulness. Little research exists to back up the benefits, and this is an uncommon course of action for regulating the circadian rhythm.
Sleeping Pills: Sleeping pills may help you fall asleep more easily, however it remains unclear whether they cause a shift in the circadian rhythm. What’s more, many people become dependent on sleeping pills, so this option has serious drawbacks.

In any case, your physician will recommend the best course of action and decide whether any of these drugs are suitable for you or not.

Sleep Deprivation Phase Advance

Another method of resetting your circadian rhythm involves staying up for 24 hours and going to bed 90 minutes before your normal bedtime. Settle on this new bedtime for a few days and repeat. Do this several times, each time settling on the new time for a while. Stop as soon as you’ve achieved your desired bedtime. Experts disagree on the effects of this method, with some suggesting that it may do more harm than good.

Final Thoughts on the Treatments

Just how effective these treatments are differs from patient to patient. No doubt, consulting your physician is the first step. Nonetheless, all these methods can help to regulate your circadian rhythm and are worth checking out.

How to Maintain a Healthy Circadian Rhythm

So, what can you do to keep your circadian rhythm in check? Well, the following tips can help:

  1. Provide Your Body with a Regular Schedule: Set a sleep-wake routine that you can stick to every day, even on weekends. Don’t constantly change your bedtime. Instead, help your body distinguish between sleeping and activity by going to bed and getting up approximately the same time each day. Variations up to 30 minutes are ok, but no more than that. That way, you support your natural circadian rhythm and strengthen it in the process.
  2. Contrast Light and Darkness – Sleep and Rest: Make sure to keep your bedroom dark and get plenty of bright light during the day. The sharper the contrast, the more it benefits your circadian rhythm. In addition, make sure to be active during the day and inactive at night, so napping should be avoided if possible.
  3. Avoid Circadian Rhythm Disrupters: Don’t engage in strenuous physical activity before going to bed. Avoid heavy meals, spicy food, screen time, excess drinking (alcohol and non-alcoholic beverages), light or noise in the bedroom, and other things that may stimulate your brain or body. Instead, find some sleep-promoting activities such as meditation or relaxation techniques and include them in your bedtime routine.


Getting a good night’s sleep is crucial for your overall health, so minding your circadian rhythm is essential. Simple, common sense tips can go a long way toward establishing a healthy sleeping pattern.

Working Nights and Your Circadian Rhythm

If you’re a shift worker, establishing good sleeping patterns is going to be difficult, as you will need to mimic the nighttime bedroom setting during the day. Experts have warned that prolonged night shift work can have serious detrimental health effects. This is because people who work at night are essentially working against their circadian rhythm. Doing so over many years can put your health at risk and may make you more accident-prone.

Final Thoughts

Your circadian rhythm and body clock help to determine whether it’s time to sleep or be awake. While over 20,000 tiny body clocks exist in your body, the master clock in the brain sets the circadian rhythm. The interplay between darkness and light over a 24-hour period determines your melatonin levels, which then either induce sleep or have you fully awake. A variety of factors can have a negative impact on your circadian rhythm, leading to many different sleep disorders. However, by setting a regular bedtime routine and keeping your body on a regular daily schedule, you can support and maintain a healthy circadian rhythm. If you are still experiencing the symptoms of irregular circadian rhythm like wanting to settle for the night very early or very late, you should take a trip to the doctor and discuss your symptoms. Thankfully, a variety of treatments are available to reset your circadian rhythm. 


WRITTEN BY: Natasha Nikolova