The Biological Clock: Why It is Important & How It Affects Health

The Biological Clock: Why It is Important & How It Affects Health

Do you know our body also has a clock? It is called the biological clock and is housed in the brain. The biological clock is so vital to the working of almost everybody process that if this gets upset, our health suffers.

Let’s know more about the biological clock and how to keep it ticking in good condition.

What is the Biological Clock and Where is it Located

The biological clock is an intricate internal clock that’s located in the hypothalamus region of the brain. It is a group of about 20,000 nerve cells in the brain called the suprachiasmatic nucleus, or SCN. This is actually the master clock that coordinates several other smaller internal clocks – made of genes and proteins – located throughout the body and operating in a feedback loop. The master clock coordinates all other body clocks to ensure everything runs in a synchronized manner and the body processes work as intended.

Whether we are sleeping or awake, the biological clocks in our bodies keep ticking in tandem with a rhythm called the circadian rhythm

First, let’s know a bit about the circadian rhythm.

What are Circadian Rhythms

Circadian Rhythms

Circadian rhythms are physical, mental, and behavioral changes that follow a roughly 24-hour cycle, linked to the light and darkness in our environment. Our biological clocks are synchronized with this circadian rhythm driven by the day/night cycle of sunlight that recurs on a daily basis. 

The master clock located in the hypothalamus in the brain is situated right above the point where optic nerves responsible for the vision cross. This location keeps the master body clock synched in with sunlight cues that regulate it. Along with light, genes also play a role in biological clock functioning.

Just as we have a cyclic sleep-wake pattern linked to the circadian rhythm, there are many more processes in the body driven by the very same patterns that regulate the biological clock. 

What all does the Biological Clock Influence

The biological clock gives signals following which hormone production related to various physiological functions rises and lowers. This means that almost every process – simple to complex – in the body is linked to the biological clock. These include sleep, alertness, hunger, metabolism, fertility, mood, body temperature, immunity, blood pressure, blood sugar levels, and more. 

Even seemingly simpler issues like moody blues, hunger and alertness can be traced to biological clock dysfunction. These are in turn linked to more workplace mishaps and traffic accidents. Upset circadian rhythms and biological clocks are also linked to cognitive impairment linked to aging.

Biological clock and sleep connection

The foremost way to experience our body clock is via the sleep-wake cycle. As we all know, we feel sleepy when it is dark and alert when it is daylight. Our sleep-wake cycles, linked intimately to our circadian rhythms, are controlled by the biological clock via a hormone called melatonin. When the master clock perceives less light, it instructs the brain to produce more melatonin to induce drowsiness. When the sun rises, the master clock inhibits melatonin production for the brain to start its awakening processes. 

Biological clock and immune function

Biological clock influences immunity as during sleep, the immune system stays active to produce and release cytokines, proteins that work as signalling molecules for fighting infectious microbes. Even the time of infection can have implications on severity of the infection. Babies that get vaccination in second half of the day and sleep thereafter show better immune responses.

In states of infections, inflammation, and stress, some types of protective cytokines are secreted in larger quantities to help the body heal. When you are sleep deprived, these cytokines may not be made in sufficient quantities that may further affect recovery.

Biological clock and mental health

Mental health disorders are often accompanied by altered circadian rhythms and upset biological clocks. The levels of hormone serotonin - believed to be linked with a feeling of wellness - fluctuates as per the availability of light in the environment. Low levels of serotonin are linked to sadness, depression, and anxiety.

What Happens if the Biological Clock Dysfunction Happens

The biological clock can get out of sync. Changes in light and temperature, traveling across time zones, night shift work, etc. can all interfere and throw it off balance.  

Sometimes the dysfunction may also be due to some biological or genetic reasons. Aging also affects biological clocks. It is believed that the presence of cataract in elderly eyes can reduce sensing of natural light by the SCN leading to upset sync with circadian rhythms and that accelerates age-related disorders. Alcohol consumption can also upset the biological clock.

Temporary dysfunction

If the changes are temporary, the clock usually resets itself after a while, like it happens during jet lag that occurs when flying long distances across time zones. The fatigue and grogginess associated with the jet lag are actually symptoms of the biological clock upset due to sudden forward or backward shift in daylight or dark hours as one shift from one-time zone into another. It might take a few days but your biological clock eventually resets itself.

Prolonged dysfunction

Those who work night shifts on a regular basis, or travel across time zones too frequently, or have a biological or genetic reason for circadian rhythm upset, can suffer from prolonged biological clock dysfunction.

When sync with the circadian rhythms is upset, the biological clock also gets disturbed, and prolonged disturbance can result in various disorders:

Sleep disorders, mental health disorders (depression, bipolar disorder, seasonal affective disorder), diabetes, obesity, heart function, immunity response, cognitive impairment, and many more. 

Prolonged biological clock disturbance can mean that:

  • Heart patients are at greater risk of heart attacks.
  • Diabetics can see sharper rise and fall of blood sugar levels.
  • Higher infection risk due to lower immunity.
  • Upset metabolism and weight gain can happen.
  • Mental health disorders can worsen.
  • Sleep disorders can become chronic.
  • Aging-related cognitive impairment can worsen.

How to Keep Your Biological Clock Ticking in Good Condition


To keep your biological clock functioning smoothly, first pay attention to your body’s natural rhythms. Follow your biological clock by sleeping and waking at appropriate times.  Keep your schedule on track by eating and sleeping at regular hours. Practice good sleep habits such as no caffeine close to bedtime, early dinner, peaceful sleeping area, and 7 to 8 hours of undisturbed sleep. 


A disciplined life in sync with the circadian rhythm of day and night is the best way to keep the biological clock in good shape that in turn helps your overall wellness.

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