December 03, 2020 9 min read

In these modern days of technology, almost everybody's health and daily life are affected by electronic devices. You just can't imagine how the overuse of electronic devices, especially the light emitted from their displays, impacts our minds and bodies. Moreover, reduced sunlight exposure due to indoor, sedentary work, and lifestyle has also disturbed our natural mechanism. Read on, and we'll discuss what is circadian rhythm and how improper light exposure can disrupt our circadian rhythms to affect our brains and bodies.

Circadian Rhythm: The Internal Clock of the Human Body

Circadian Rhythm is the body’s internal rhythm that follows the in-builtBiological Clock.This rhythm controls your day’s (24 hours) schedule for wakefulness and sleep. In simple words, this is the body’s cycle that informs you when to sleep and when to wake up. It is nature’s alarm clock that reminds you to get active or slow down and rest.

circadian rhythm

Circadian Rhythm Concept

Think of the human body as a complex, systemised, and highly organised machine, and the deeply integrated clogs of the human brain are no less than a miracle. The Suprachiasmatic Nucleus in the human brain delivers power during the day and also induces sleep by night. It does this by managing specific processes which include:

  1. Perception of the amount of light 
  2. Release of hormones (melatonin and cortisol)
  3. Metabolism and body temperature

Keep reading, and we will help you learn everything you need to know about circadian rhythm.

Importance of the Circadian Rhythm

The circadian rhythm is vital in the maintenance of the body.

Healing and Repair

A normal circadian rhythm is pivotal in maintaining a healthy mind and body. It guides your body to rest after a hectic day. The circadian rhythm allows for the healing and regeneration of the damaged cells in your body. Circadian rhythm also accelerates wound healing (Cable et al., 2017).

Even our ancestors knew the importance of following nature's clock and having a good night's sleep. In ancient times, they considered night time as the healing time for the body. Studies have shown that good quality sleep at night can also boost your immunity.

Another study claims that disrupted circadian rhythms can cause delayed wound healing (Mesut, Kursad, and Serhat, 2014).

Energy Levels

Circadian rhythm determines the energy levels of your body. Your brain releases chemicals and hormones during the day to promote your working conditions, and when the levels dip down and your brain recognizes that it is night time. Certain endogenous chemicals (mostly protein in nature) are also released by the brain that increases your energy levels and keeps your alert and active.

Irregularity Leads To Diseases

Irregularity of circadian rhythm results in manychronic health diseases such as sleep disorders, depression, and obesity. Several sleep disorders are also associated with irregularity in sleep-wake cycles. Irregular circadian rhythm is associated with an increased risk ofParkinson’s disease. This is because disruption in the circadian rhythm is suspected of worsening the neurodegenerative issues.

How Light Carves Our Lives

The pattern of our exposure to light has a potential effect on our daily routine, sleep quality, and overall health. Increased sunlight exposure during the daytime keeps us awake and active, while light exposure at night (from devices and artificial lights) may disturb our sleep.

Circadian Lighting

The circadian rhythm of the body depends upon the amount of light received by the eyes. This light and you can add artificial light to control the rhythm. This light is calledcircadian lighting

The Hypothalamus in your brain works by counting on the signals from your eyes. High intensity of light received by the eyes is signaled as daytime while absence is considered as night. It works in coordination with the pituitary gland and the adrenal glands to induce sleep or inculcate alertness.

Cortisol Secretion

Cortisol is a steroid hormone synthesised and released adrenal glands and is a steroid hormone. Hypothalamus and the pituitary glands control the release of cortisol from the adrenals. The hormone keeps us alert, active, and energetic throughout the day.

The Hypothalamus-Pituitary-Adrenal axis (HPA) regulates sleep. This hormone wakes you up with the sunrise. A rapid rise in cortisol levels is seen at first-morning awakening known as the Awakening response. Cortisol levels peak at around 9 am.

Melatonin Secretion

Melatonin is a sleep-inducing hormone released by the pineal gland. It reaches maximum levels at night time, and the brain senses low melatonin levels as daytime. Therefore, it is considered as theSleep hormone because it regulates the induction of sleep.Higher levels of melatonin result in a better sleep even during the day time.

Melatonin is effective in inducing sleep. According to a1999 study,researchers found that the melatonin secretion’s timing was important in inducing daytime sleeping in the nurses.


Causes of Disturbed Circadian Rhythm

The circadian rhythms can be disturbed by several activities, as described below:

1. Working Long Shifts 

Long, erratic shifts can tire you out. The outcome of this is a rhythmic disturbance. Health care professionals, firefighters, and mining workers have to work for long strenuous hours. Athletes preparing for competitions are also exposed to excessively high strain training sessions that can disrupt the sleep-wake cycle.

2. Late night/Overnight Work

Working late at night or night-shift duties can disturb the circadian rhythm. People who perform duties without natural light have to suffer the plight of abnormal circadian rhythms. It includes night guards, security men, and doctors even.Athletesmay also experience similar sleep issues when training in the evenings.

3. Stress and Mental Health Conditions

Stress can also be a cause. As stress is related to the release of different hormones, a breach in the circadian rhythm is expected. Various mental health issues, such as mental disorders, can also interfere with the rhythm.

People suffering from depression often complain of having abrupt cycles of sleep.

4. Poor Sleeping Habits 

We hate to accept this, but we have become a generation with the worst habits. By we, I mean the vast majority and not everyone. Whether it is sleeping, eating, or using smart devices, we seem to have no routine, no schedule at all. 

A lack of proper routine can lead to circadian rhythm problems. It is the central issue of the modern age. The younger generation spends more time on their phones and tablets, playing games, and surfing the internet. Waking up late at night and sleeping in daytime works against the natural ways. 

5. Traveling 

Traveling can affect the sleep-wake cycle in two ways. 

If you travel by airplane, you are likely to develop jet-lag. Jet lag is an evident cause of the disruption of the circadian rhythm. Traveling through different time zones can also be attributed to disturbances.

6. Health Conditions and Medications

Brain damage or head injuries can disturb the sleep cycle. Head injuries can also cause issues with sleeping and waking. Certain medications may also prove to be negative on your sleep schedule.Schizophrenia is also associated with disturbed circadian rhythm.


Modern Technology: A Curse for the Circadian Rhythm

man on phone in bed

Despite knowing how complex it is for the brain to maintain the normal sleep-wake cycle, we keep testing the limits. 

The manufacturing and advent ofsmart devicesisn’t a“smart idea”after all. These devices, especially smart phones, have become a curse to our health. Nowadays, it is a common habit of many to carry smart phones to their beds. You can find many articles online that show us the ugly side of the so-called smart world.

Disruption of Cortisol Levels

The Blue light emitted by the LED displays has several implications. A study carried out in 2017 by Heo and colleagues showed that the light emitted from the mobile screen disrupts cortisol levels and interferes with sleep.

Artificial Light at Night (ALAN) Disturbs Circadian Rhythm

Almost everybody uses their smartphone and tablets at night. The light exposure at night has its adversities. Exposure to artificial Light At Night (ALAN) results in disturbances of the circadian rhythm (Touitou et al., 2017). 

Light Pollution from Digital Devices Affects Our Sleep 

Not just smart phones but light pollution from any digital device can interfere with the normal working of the HPA system and, thus, the circadian rhythm (Lee et al., 2020).

phones and screens

How to Synchronise Yourself with Your Circadian Rhythm

So you want to synchronise yourself with your normal circadian rhythm? Keep reading, and the following techniques can help you go a long way:

1. Make and Follow a Routine

If you are not sure how to create a good routine, start by having a set sleep and wake time each day.  Having fixed times for this helps to create structure. Follow a routine for at least 21 days and explore the full potential of your body. 

routine & schedule

2. Sleep Optimisation (especially for athletes)

The best way to settle your issues with the mind you should work on your sleeping habits. Do as the proverb says,“Early to bed, early to rise makes a man healthy, wealthy and wise.”

As mentioned earlier, athletes suffer from circadian rhythm disturbances; therefore, they needSleep optimisation to boost recovery and performance. Sleep optimisation is also associated with better athletic performance (Simpson et al., 2017).

sleep optimisation

Knufinke and colleagues carried out a detailed study of bright light and sleep quality (light sleep, REM sleep, and deep sleep) and sleep onset in athletes in 2020. They found it a necessary for athletes to optimise their sleep and regulate their sleep-wake cycles. It may also help them in reducing their psychological strain.

The general public can also use the following sleeping tips for better results. Proper sleeping relies on several important steps, as given below:

Improve Your Sleeping Environment
Sleep in an environment that promotes sleep and rest by 
  • Block out the light
  • Set the temperature of the room to an optimal value
  • Leave all gadgets out of the bedroom, i.e., avoid sleeping with your smartphone next to you.
  • Check out our 7 Quick Hacks for better quality sleep
Don't Oversleep
Napping late in the evening and even in the night can disturb the cycles of the body. So, stop sleeping for late hours.

Engage in Healthy Activities Before Sleeping
Meditating before sleeping is an excellent activity to promote sleep. Doing light yoga, stretches or reading a book can also be beneficial.


3. Spend Some Time Outdoors

Spending time out in sunlight can be beneficial to the body. Exposure to sunlight allows for Vitamin D production in the body. Light exposure, especially sunlight, boosts your alertness and vigilance. Thus, staying out can increase your wakefulness and activity. 

4. Avoid Caffeine and Nicotine at Night

Caffeine and nicotinestimulate your central nervous system. When taken at night or in the evening, these chemicals result in the brain’s stimulation, making you more alert. That's why it is recommended not to drink tea and coffee at night.

5. Try Some Light Therapy

People with abrupt circadian rhythms due to sleep disorders can tryLight therapy. In this therapy, patients are exposed to light sessions to improve the hormonal conditions of their bodies. Its primary use is in treating depression but has applications in sleep disorders too.

6. Exercise Regularly 

Regular exercise can be extremely useful in bringing back your circadian rhythm to normality. Twenty minutes of aerobic exercise daily is recommended to stay healthy, mentally, and physically. 



A normal circadian rhythm relies on releasing hormones and proteins regulated by the eyes’ signals. Based on how much and how intense light falls on your eyes, they send signals to regulate the release of melatonin and cortisol. Melatonin is the sleep hormone, while cortisol shoots in the morning to impart alertness to you. 

Different factors can disrupt this natural sequence, including long overnight shifts, traveling, and sleep disorders, but the biggest and the worst culprit is poor sleeping habits.

The injurious use of smartphones provokes poor sleeping habits. We need to address the general public regarding this bad habit. Sleep optimisation and other above-mentioned techniques can help you synchronise with your natural circadian rhythm.


Cable, Erin J., Kenneth G. Onishi, and Brian J. Prendergast. "Circadian rhythms accelerate wound healing in female Siberian hamsters."Physiology & behavior 171 (2017): 165-174.

Mesut Sipahi, M. D., M. D. Kürşad Zengin, and M. D. Serhat Tanik. "Effects of circadian rhythm disorders on wound healing and strength of bowel anastomosis in rats."Wounds 26.11 (2014): 317-322.

Touitou, Yvan, Alain Reinberg, and David Touitou. "Association between light at night, melatonin secretion, sleep deprivation, and the internal clock: Health impacts and mechanisms of circadian disruption."Life sciences 173 (2017): 94-106.

Heo, Jung-Yoon, et al. "Effects of smartphone use with and without blue light at night in healthy adults: A randomized, double-blind, cross-over, placebo-controlled comparison."Journal of psychiatric research 87 (2017): 61-70.

Lee, Youn-Jung, Chul-Hyun Cho, and Heon-Jeong Lee. "Effects of Light Pollution from Mobile Digital Devices on Sleep and Circadian Rhythms."Sleep Medicine and Psychophysiology 27.1 (2020): 1-7.

Simpson, N. S., E. L. Gibbs, and G. O. Matheson. "Optimizing sleep to maximize performance: implications and recommendations for elite athletes."Scandinavian journal of medicine & science in sports 27.3 (2017): 266-274.

Knufinke, Melanie, et al. "Dim light, sleep tight, and wake up bright–Sleep optimization in athletes by means of light regulation." European Journal of Sport Science (2020): 1-9.

Yelana Jennings
Yelana Jennings

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