The body clock comprises organisms’ natural timing devices that regulate the cycle of circadian rhythms. This is an internal mechanism that periodically schedules the body’s activities and functions.
What Is Body Clock?
The internal body clock is the body’s natural timing mechanism that regulates certain important biological functions and activities in every living organism.
The body clock is also known as the circadian rhythm 1; it involves the 24-hour internal clock in our brain that regulates cycles of alertness and sleepiness by responding to changes 2 in light and the environments around us.
An example of a light-related circadian rhythm is sleeping at night and remaining awake during the day. This rhythmic body clock also controls the body’s metabolism, blood pressure, sleep cycle, and hormonal system.
How Does The Body Clock Work?
This body clock is also characterized by homeostasis 3. Homeostasis is the process by which every living organism actively maintains stable conditions for survival. It is related to the pineal gland, the prime center of the body’s internal clock that regulates circadian rhythms.
The gland receives information about the daily light-dark (day-night) cycle from the retinas and accordingly modulates the secretion of melatonin.
A greater amount of melatonin is secreted when it’s dark, thereby pointing to melatonin’s role in sleep. In fact, melatonin is the key hormone in the coordination between the circadian system and circadian rhythm.
However, other hormones (like vasopressin, acetylcholine, insulin, and leptin) and body temperature also influence the workings of the body clock.
Our body clock helps to regulate internal cycles that perform important physiological functions, metabolism, and behavior. It enables all living creatures to anticipate and understand the rotation of the Earth within the timeframe of 24 hours.
In mammals, influenced by the light/dark cycle, the circadian clock optimizes metabolism and energy harvesting. The sleep-wake cycle 2 is one of the most important circadian rhythms, synchronized as it is by a master clock in the brain.
Some environmental cues, especially daylight 4, directly influence the master clock. It is a clock in the brain that coordinates all the other biological clocks in a living being’s body.
In vertebrate animals 5, including humans, it is a group of about 20,000 neurons 6 that form a structure called the suprachiasmatic nucleus (SCN). Situated in the hypothalamus of the brain, it receives direct input from the eyes. That’s why the day and light cycle is tied to the circadian rhythm.
What Affects The Circadian Rhythm?
The biological clock is influenced by certain behavioral patterns and external stimuli. This clock influences some core activities of the body, including:
The internal body clock and food intake are directly related to metabolism 7, as it is the only factor responsible for energy production.
The body clock controls the sleep-wake cycle, with light being the main external stimulus that influences the rhythm.
Aging 8 is also associated with the body clock. In fact, due to old age, elderly people experience difficulties in completing basic day-to-day activities linked to energy production and sleep.
For synchronizing circadian rhythms, food is considered the main stimulus. This clock regulates cellular differentiations and the cell cycle. However, the process is yet to be understood well.
5. Immune response
It has been observed in research that body clock affects the immune system responsible for the change in response to bacterial infection. In particular, specialized cells called macrophages, which are big cells that engulf and kill bacteria.
6. Physical and psychological disorientation
Sometimes traveling may cause physical and mental exhaustion. Such a condition disrupts the body clock.
Causes Of Circadian Rhythm Disruptions
Circadian rhythm disruptions and, in more severe cases, body clock disorders may set in for a variety of reasons. These include:
1. Shift work
Lifestyle patterns, especially shift work 9, can trigger circadian rhythm disorders. Several studies attest that constant or recurrent patterns of sleep interruption results in insomnia or excessive sleepiness.
Most night shift workers experience difficult sleeping patterns and disturbances in their bodily functioning. This can also trigger metabolic changes and severe changes in weight and mood.
2. Jet lag
When people travel across multiple time zones, they frequently face difficulties in adjusting to new schedules due to jet lag. Attributed to a brief disruption in the internal body clock, jet lag makes people experience brain fog, sleeping problems, and disoriented feelings.
3. Delayed sleep disorder
Delayed sleep disorder syndrome 10 is a type of circadian rhythm disorder commonly prevalent in people who have a habit of staying awake into the late hours of the night and waking later in the morning. Mostly the younger generations, who are comfortable addressing themselves as ‘night owls”, experience its symptoms.
Read More About Sleep Disorders Here
4. Effect of drug and alcohol intake
Certain drugs and alcoholic drinks 11 cause circadian rhythm disruptions, even inducing sleep disorders. Consuming alcohol during the evenings may cause unnecessary sleepiness, whereas consuming it late at night may cause sleep disruptions throughout the night. Other substance intakes (like narcotics) can also disrupt our body clock and mental health.
Read More About Alcoholism And Mental Health Here
5. Irregular sleep-wake disorder
People who are in the habit of taking short naps throughout the day or those with no proper sleeping pattern may experience body clock disorders, particularly irregular sleep-wake disorder.
Moreover, people with neurological conditions (such as dementia), children with intellectual disabilities, and people with traumatic brain injuries may also experience disruptions in the body clock.
Circadian Rhythm Disruption And Physical Health
Circadian rhythm disruptions can trigger certain physical health symptoms linked to:
- Reduced life expectancy
- Increased risk of cancer
- Cardiovascular diseases (like stroke and heart attack)
- Metabolic syndromes
Read More About Obesity Here
Circadian Rhythm Disruption And Mental Health
Circadian rhythm disruption affects mental health—triggering severe mental health conditions like:
- Decision-making problems
- Depressive disorders [Read more]
- Mood disorders [Read more]
- Sleep disturbances
- Decreased alertness
- Cognitive impairment (memory disorders like dementia, Parkinson’s disease, etc.).
Read More About Dementia Here
How To Maintain A Healthy Body Clock
The focus of the treatment of body clock disorders is to reset a disrupted circadian system and reinstate a healthy sleep-wake cycle. Specialists generally chalk out treatment plans depending on the severity of the problems experienced and the type of body clock disorder.
1. Bright light therapy
In this type of therapy, the patient is advised to plan a particular time daily to sit in front of a lightbox. The lightbox will provide a variety of bright lights, such as sunlight. Light visors and light glasses are generally used in this therapy. Bright light therapy 12 adjusts the amount of melatonin the body makes and resets the sleep cycle.
2. Melatonin supplement
Melatonin supplements 13 are generally prescribed to treat delayed sleep disorders, irregular sleep cycles, etc.
3. Healthy lifestyle changes
A healthy lifestyle 1 helps in reducing circadian rhythm disorder symptoms and, therefore, experts suggest patients follow a well-planned daily routine. This routine may include a scheduled meal time, a good sleep hygiene regime, adequate exercise, limited intake of caffeine and alcohol, etc.
A healthy body clock is central to our sound mental and physical well-being as well as everyday functioning. Therefore it is important to listen to your body clock and maintain it well. Due to hectic schedules and disruptive lifestyles, it may not be always possible to stick to habits that ensure a sound circadian rhythm.
It also takes time and effort to reset a disoriented body clock and, in the process, everyday functioning. However, it is assured that the changed lifestyle will lead to improved motivation and greater productivity.
At A Glance
- The body clock is an internal mechanism that periodically schedules the body’s activities and functions in living beings.
- It is also known as the circadian rhythm.
- It controls metabolism, blood pressure, sleep cycle, and hormonal secretions.
- It coordinates physiological and behavioral activities, matching with environmental variations.
- Disruptions in the body clock can lead to several mental and physical health conditions.
- Circadian rhythm disruptions and disorders can be easily addressed with light therapy, pharmacotherapy, and self-help coping strategies.
Frequently Asked Questions (FAQs)
1. How do mental disorders affect the circadian rhythm?
Mental health disorders like mood disorders, sleep disorders, eating disorders, and substance use disorders can disrupt the circadian rhythm, thereby enhancing the risk of body clock disorders.
2. How can we reset the body clock?
Attempting to follow a healthy lifestyle that includes regular meal and sleep times as well as adequate exercise can be a good step towards resetting and correcting a disrupted body clock.
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