Circadian Rhythm Disorder and Depression-What Should You Know?

Circadian Rhythm Disorder and Depression-What Should You Know?

The circadian rhythm, also known as the biological clock, is a schedule that controls various bodily functions, such as sleep and hormone secretion. A biological or circadian rhythm is a cycle that follows the movements of every living organism. It is characterized by a varied alternation in levels of chemicals in the body. Today we are going to talk about Circadian Rhythm Disorder and Depression.

Although these rhythms are naturally adapted to various external factors, the external environment influences their regulation! However, people with significant depression, also known as clinical depression, have disturbed circadian rhythms throughout brain areas.

Sleep disruption is a common symptom of depression that sleeplessness and excessive sleeping are the first things clinicians look for when diagnosing depression. Scientists have now discovered a malfunctioning body clock in the brains of patients suffering from depression for the first time. 

Researchers compared post-mortem brain samples from mentally healthy donors to persons who died while suffering from severe depression. Individuals with more frequent disruptions in their circadian rhythm were more likely to have major depression and bipolar disorder symptoms.

Types of Biological Clock/Circadian Rhythm

The biological clock is an innate time device in living organisms that internally regulate or govern “Biological rhythm.” Innate means automatically set or built-in clock. Nearly all living organisms have a biological clock. There are many types of biological rhythms/clocks. The prominent types of biological clocks are discussed below.

  • Ultradian biological clock: This type of biological rhythm is repeated in a short time which is less than 24 hours. Such as blood circulation, pulse, heart rate, blinking, appetite, micturition, arousal, etc.
  • Infradian biological clock: This type of biological rhythm takes more than 24 hours for a repeat. This rhythm takes days, weeks as well as nearly or over a month for a repeat. This rhythm has some subtypes:
  • Circaseptan cycle: Take 7-10 days for a repeat. Such as mood.
  • Cireadiseptan cycle: Take 14-18 days for a repeat. Such as ovulation. 
  • Circavigintan cycle: Take 20-23 days to repeat. Such as coordination strength.
  • Circatrigintan cycle: Take 28-33 days to repeat. Such as the menstruation cycle.
  • Circadian biological clock: Circadian biological clock is the most popular biological rhythm. This is the only biological rhythm that is as similar as our countable daytime (24h). The internal mechanisms of an organism that is repeated within 24 hours are known as circadian biological rhythm. The organisms which are properly adjusted with the sunrise & sunrise system of the earth contain this biological clock. Such as sleeping, opening or closing of stomata of plant, sleeping movement of Albiya plant, etc.
  • Circannual biological clock: Circannual biological clock is the biological clock that repeats the internal mechanism just after 1 year(365 days). It occurs for the hormonal or enzymatic change at a particular season of its appearing in animal or plant, such as the mating season of dogs, migration of birds, flowering or fruit formation of (apple, mango, jackfruit), etc.
  • Circatidal biological clock: This type of biological clock depends on the flow of tides in the sea or river. The mechanisms are repeated at the time of tides. Such as mulaskas collect food at the time of tide, some small fishes come to the beach to form their egg, etc.
  • Circalunar biological clock: This type of biological clock depends on the size or shape of the moon. When the moon is full fill, it is called the lunar clock, and when the ½ or ¼ of the moon is filled, it is called the semilunar cycle. For example, polycids are formed in moonlight; fishes form their eggs at ½ moon or ¼ moon.

Stimuli for Circadian Rhythm

In the case of the biological clock, there need stimuli that lead the biological rhythm. There are three types of stimuli exogenous, endogenous, and Exo/endo synchronization. The stimuli are described below:

  • Exogenous stimuli: The environmental change which controls the source of stimuli in genes is called exogenous stimuli. When the sun rises or sunsets the temperature, the light stimuli these genes for the hormone secretion, and we wake up and go to sleep. The fruits found in the summer season are not found in the winter season because the hot weather stimuli the genes to complete the changes and secret the enzymes.
  • Endogenous stimuli: Some biological clocks are occurred or are controlled by hormones. Hormones stimulate the body to complete the cycle of the biological clock, such as the maturation cycle, ovulation cycle, periods, etc.
  • Exo/endo synchronization stimuli: This stimulus is the combination of both exogenous & endogenous stimuli. Such as sleep and wake are repeated by exogenous stimuli, sunlight and endogenous stimuli are the melatonin hormone that controls sleep. Apple formed in the winter season here the season is exogenous, and the active genes which are reasonable for flower blooming and fruit forming are endogenous stimuli.

Circadian Rhythm Disorder and Depression

Is there any relation between Circadian Rhythm and Depression? A person’s ability to sleep and function properly can be harmed by an irregular circadian rhythm, which can lead to numerous health complications, including mood disorders, depression, anxiety, and mental illness. 

Circadian rhythm is the 24-hour ‘internal clock’. This inner clock controls the sleep-wake cycle of your body. Throughout a 24-hour day, the visual cue of daylight – particularly the intensity of light, the period of minutes sunlight, and when exposed to light – helps to “set your biological clock.”

Light travels through your eyes and into the “control center,” a portion of your brain. Physical activity, socialization, and melatonin (a hormone that is produced in the brain that plays a significant part in sleeping) are all factors that influence your body’s circadian rhythm. Your age could also have an impact on your sensitivity towards the sleep-wake cycle.

The most satisfactory conclusion that we can come to is malfunctioning Circadian Rhythm in the brain can cause depression. Circadian clock-controlled responses including sleepiness and cortisol levels are frequently interrupted in mood disorders.

Final Words

What conclusions can be drawn from all this? Malfunctioning Circadian Rhythm can cause extended depression and anxiety-like responses. Hope you have learned some great information on Circadian Rhythm Disorder and Depression. If you have further questions then write in the comment section. 

Hridoy Kumar Paul is experienced in pharmaceutical and health blogs, author, and founder of Currently, Hridoy is pursuing a Bachelor of Pharmacy degree at Jashore University of Science and Technology, Bangladesh. Articles on are general information and are not intended to substitute for professional advice. The information is "AS IS", "WITH ALL FAULTS". User assumes all risk of use, damage, or injury. You agree that we have no liability for any damages.

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    Sadman 1 year

    Wow! What’s an informative article! ❤️❤️