Circadian Rhythms: How Do They Influence Our Health?

The alteration of circadian rhythms is a risk factor for several diseases. Although many people ignore it, they regulate processes that're crucial for our health. In this article, we'll tell you all about it!
Circadian Rhythms: How Do They Influence Our Health?

Last update: 29 September, 2021

Circadian rhythms can be compared to an internal clock that all living beings have. Human beings are part of this global ecosystem. Therefore, we also synchronize with the environment.

This synchronization is achieved thanks to circadian rhythms. These mark the beginning and end of various physiological processes that our bodies carry out in daily cycles. These cycles respond, in particular, to two variables: light and darkness.

Animals, plants, and even the tiniest of microbes have this internal clock that allows them to synchronize their activity with the rotational movement of the earth. So their processes form a biological periodicity of 24 hours, and chronobiology is the study of these phenomena.

Franz Halbert coined the term “circadian rhythms.” He introduced the term in 1950. However, the subject had been studied since the mid-19th century. Some of the scientists who developed this concept in depth were Jeffrey C. Hall, Michel Rosbald, and Michel Young, in 1980.

How do circadian rhythms work?

The circadian system is composed of a visual component, represented in the photoreceptors. These generate a signal called “circadian,” which reaches the effector systems; a network that secretes certain substances when it receives a specific stimulus.

The signal or information reaches the brain where it’s processed through an area called the suprachiasmatic nucleus. Once this occurs, the brain issues orders to the rest of the organism to carry out the corresponding synchronization.

Depending on the circadian rhythms, we feel hungrier at certain times of the day or feel sleepier. In addition, the synchronization of this internal clock determines how much energy we need at any given time of the day. As a result, it regulates metabolic processes.

These rhythms are part of the biological clock, which is an innate timing device that’s present in all organisms. Overall, there are three biological clocks:

  • Circadian rhythms. These are cycles of approximately 24 hours.
  • Infradian rhythms. They have more than 24 hours; an example is the menstrual cycle, which takes around 28 days.
  • Ultradian rhythms. They last less than 24 hours; an example of these is the phases of sleep.
A woman with a clock
Circadian rhythms determine processes such as the sensation of hunger or sleep at certain times.

How circadian rhythms influence health

Circadian rhythms don’t directly influence our health. However, alterations in this cycle make organisms more prone to suffer certain diseases. Its relationship with metabolism is key in preventing or favoring the onset of certain health issues, such as diabetes and obesity.

Circadian rhythms influence, and to a large extent determine, sleep and wake cycles, hormonal cycles, eating habits, body temperatures and even healing processes. Therefore, their imbalance could favor the appearance of diseases linked to these aspects of our health.

Irregularity in these rhythms is related to sleep disorders. In addition, this is a factor that has the potential to give rise to other physical health issues. In addition, they’re also related to mental conditions such as depression, bipolar disorder, and affective disorders.

Michell Young points out that circadian rhythms even influence the effectiveness of drugs or treatments such as chemotherapy. These are most effective at certain times of the day. In fact, there may be fewer side effects if we take certain drugs at certain times.

A woman with insomnia
Specialists associate an uncontrolled circadian rhythm with sleep disorders.

Factors that produce alterations in these cycles

Circadian rhythms can become disrupted and unbalanced for several reasons. Currently, specialists believe that certain factors associated with modern life have a negative influence on them. For example, the excessive use of artificial lights, night shift work or work with little natural light, eating at any time of day, and lack of sleep.

The phenomenon known as jet lag, which occurs when changing time zones abruptly, could also favor this alteration. Other causes that contribute to altering circadian rhythms are:

  • Sedentary life
  • Uncontrolled eating habits
  • Inadequate changes in sleep patterns
  • Internal body mutations

In conclusion, these cycles are a means of harmonization with the environment in which we live. Keeping them in balance is fundamental to preserve good health. In conclusion, this can be achieved by leading a healthy lifestyle and, above all, by respecting the natural hours of sleep and eating.

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  • Guadarrama-Ortiz, P., Ramírez-Aguilar, R., Madrid-Sánchez, A., Castillo-Rangel, C., Carrasco-Alcántara, D., & Aguilar-Roblero, R. (2014). Controladores del tiempo y el envejecimiento: núcleo Supraquiasmático y glándula pineal. International Journal of Morphology, 32(2), 409-414.
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