Biological Rhythms

Biological Rhythm Definition

The Biological rhythms are the natural cyclic changes in the body. It maintains both the chemical or function changes. It functions as an internal clock master and coordinates with the other clock in the body. They are made up of thousands of nerve cells, which sync to the body functions. The biological clock in human located in the brain and connected with the nervous system. The periodic biological fluctuation in the body corresponds to the environmental changes and biological changes  

Types of Biological Rhythms

Based on the functions of Biological rhythms are classified into four types. The types of biological rhythms  are 

  1. Circadian rhythms

  2. Diurnal rhythms

  3. Ultradian rhythms

  4. Infradian rhythms 

Circadian Rhythms: The Circadian rhythm is a 24-hour cycle, It is a part of the body’s internal clock. They are running to carry our essential functions and process of the body. One of the well-known circadian rhythms is the sleep-wake cycle. The different system of the body follows the master clock of the brain, which synchronize with circadian rhythms. The circadian clock plays an important role in a physical, mental, and behavioural role that depends on light and dark.


Diurnal Rhythms: The diurnal rhythms are also known as endogenous rhythms. It syncs the day and night with circadian rhythms. It is mainly influenced by environmental clues like climate changes. 


Ultradian Rhythms: The Ultradian rhythms occur more than once a day. It lasts for short period at high frequency. For example, deep sleep for ninety minutes. The alertness and hormone level follow the ultradian rhythms.  


Infradian Rhythms: A biological rhythm, which lasts for more than 24 hours is because of Infradian rhythms. For example, the menstrual cycle in women occurs every 28 days. 

Biological Clock in Humans

In the human body, Suprachiasmatic Nucleus (SCN) present in the brain is the main biological clock, which regulates the circadian rhythm of sleep. The Suprachiasmatic Nucleus is located up the right corner of the nervous system in the hypothalamus. Here, the light stimulates the retina’s receptors and sends a signal to the Suprachiasmatic Nucleus. Then they send a signal to the pineal gland for melatonin secretion. The melatonin hormone regulates the proper sleep cycle. Serum cortisol concentrations rapidly increase in the early morning hours, gradually decrease during the day, with small elevations after meals, and remain decreased for much of the night.

What are the Types of Biological Rhythm Disorders?

Every biological disorder impacts the circadian rhythm. The biological rhythms are disturbed by various factors. 


Sleep Disorders: The body’s health is related to the sleep cycle. The prolonged distribution of the regular sleep cycle affects the biological rhythms. It causes sleeping disorders like insomnia


Jet Lag: Overnight travel across the time zones disturbs the circadian rhythm. And causes biological rhythm disorders. 


Mood Disorders: The biological rhythm disorders also occur if people lack exposure to sunlight. This causes depression, seasonal affective disorders, and bipolar disorders. 


Shift Work Disorders: The people who are working in the rotational shifts cause changes in circadian rhythms and it may lead to shift work disorders. 

Biological Rhythm Disorder Causes

Biological rhythms psychology disorders affect the person’s health and hormonal changes. The list of factors that causes the biological rhythm disorder are

  1. Anxiety

  2. Depression

  3. Lack of mental alertness

  4. Diabetes 

  5. Obesity

  6. Daytime sleepiness

  7. Physically inactive

  8. Irregular sleeping habits

  9. Being more accident-prone

Risks of Biological Rhythm Disorder 

The people who are working in the rotations shifts are facing high risks of biological rhythm disorder. This causes hormonal imbalance and various other diseases. The US researchers found that about 15% of the rotational shift workers are getting affected by these disorders. 


For example, healthcare workers, travellers, police officers, drivers, pilots, and others in transportation, food preparers, and servers, and firefighters are at a high risk of biological rhythm disorders. According to the NSF survey, only 63% of workers felt that they had enough sleep.

How to Maintain a Healthy Circadian Rhythm?

It is important to have a balanced circadian rhythm for maintaining a healthy life cycle.  Here, the perfect chart for balancing healthy circadian rhythms is listed. 

  1. Exploring natural light and setting the body clock cycle accordingly helps to build a healthy circadian rhythm. 

  2. To have a perfect sleep time, practice the biological clock sleep by maintaining regular bedtime as it affects the biological clock circadian rhythm 

  3. A regular exercise with healthy activity during the daytime supports the biological rhythms psychology and helps to sleep earlier. 

  4. Alcohol consumption and caffeine affect sleep and biological rhythms. Reducing intake of caffeine impacts the hormone.  

  5. Often exploring the artificial lights during night time impacts the body clock cycle. Limited exploring to electronic gadgets helps to improve healthy biological clock in humans 

  6. Day time sleep affects the natural routine and impacts the biological clock circadian rhythm.

FAQs (Frequently Asked Questions)

Q1. Why are Biological Rhythms Important?

Ans. In human life, biological rhythms maintain the whole body to work properly.  The biological clock manages the timing of every individual’s behaviour like a sleep-wakeup cycle, eating, activity, cognition, mood..etc. Biological rhythms also manage the individual’s cell functions, physiology control like metabolism, blood pressure, body temperature, DNA repair, cell cycle, etc.  The biological clock circadian rhythm controls a part of the brain through the suprachiasmatic nucleus, which is a group of cells in the hypothalamus, that respond to light and dark signals. 

Q2. What are the 4 Biological Rhythms?

Ans. The biological rhythms are mainly classified based on their function routine. They are classified into four types namely, circadian rhythms, diurnal rhythms, ultradian rhythms, and infradian rhythms. The circadian rhythm takes 24 hours cycle and it takes responsibility for physiological and behavioural changes like sleeping, eating..etc. Diurnal rhythms help to syncs the day and night for circadian rhythm, it also adjects according to the environment clues. Ultradian rhythms last for the shortest period at high frequency. Infradian rhythms last for more than 24 hours. The best example of the infradian rhythms is the menstrual cycle. Usually, mutation or changes in certain genes impact biological rhythms. Shift work and light from electronic devices also affect biological rhythms.