Do you know about the biological rhythms? What are the internal biological clocks? How time affects the biological events of your body? How do cellular processes interact to produce daily rhythms? Do our circadian rhythms increase your body’s fitness? How is your optimal performance affected by biological rhythms?

What is the Chronobiology?

Chronobiology is a field of biology that provides knowledge about the timing processes in living organisms such as cyclic phenomena. The periodic phenomena include the adaptation of living organisms to the solar and lunar rhythms. These cyclic phenomena are known as biological rhythms.

What are your biological rhythms?

Biological rhythms can be defined as the natural cycle of alterations in the chemicals or functions of your body. This natural cycle of alterations is like a clock that is responsible for the coordination of other clocks in your body. The location of this clock is in the brain where it is in the right above of the nerves where the eyes cross. The clock contains thousands of nerve cells that play an especially important role in syncing the functions and activities of your body. The biological rhythms of your body are mainly of five types:

  • Circadian rhythms
  • Diurnal rhythms
  • Infradian rhythms
  • Ultradian rhythms
  • Circannual rhythms

Circadian rhythms

These rhythms can be defined as the biological rhythms which involve the 24-hour cycle that runs for physiological and behavioral changes such as sleeping. The body has circadian clocks that regulate the timing and circadian rhythms in most tissues and organs of your body. The examples of circadian rhythms involve:

  • Sleep-wake circadian rhythm
  • The body-temperature cycle

Sleep-wake circadian rhythm

It is an example of circadian rhythm and can be defined as an internal clock that runs constantly and cycles between sleepiness and alertness. These circadian rhythms are not just present in humans but also play a particularly important role in animals, microbes, and plants.

The body-temperature cycle

It is an example of circadian rhythm which involves the twenty-four-hour alteration of the core body temperature. The endogenous circadian pacemaker plays a very important role in its regulation that is located in the suprachiasmatic nucleus. The thermoregulatory mechanism involves heat production and heat loss, so the expression of circadian rhythm is modified by this thermoregulatory mechanism.

Diurnal rhythms

These biological rhythms can be defined as circadian rhythms that are synced with day and night. The word diurnal is derived from the Latin word diurnal meaning, “of the day”. So, the diurnal means is being active during or in the daytime. Examples of diurnal rhythms involve:

  • The activities repeat once every twenty-four hours.
  • Many flowers have a diurnal pattern means they open their blooms once every twenty-four hours or in other words in every morning.

Ultradian rhythms

These biological rhythms can be defined as rhythms for a short period and have a very higher frequency as compared to circadian rhythms. There are several examples of ultradian rhythms in the human body such as:

  • Thermoregulation
  • Micturition
  • Arousal
  • Blood circulation
  • Heart rate
  • Pulse rate

Infradian rhythms

These biological rhythms can be defined as rhythms for more than twenty-four hours. There are several examples of these types of rhythms in the body of living organisms such:

  • The menstrual cycle in women
  • The hibernation cycle in bears
  • Breeding, migration, and molting in animals.

Circannual rhythms

These biological rhythms can be defined as the rhythms that consist of an endogenously generated sequence of activities that takes almost one year to complete.

Examples of these types of rhythms involve:

  • Hibernation cycles in ground squirrels
  • Cycles of reproductive activity
  • The pupation rhythm in carpet beetle
  • Molting in ungulates
  • The urge to migrate in birds.

Importance of biological rhythms

  • Biological rhythms are important in the coordination of the timing of behavior, physiology, and the cell function of the individual.
  • These are important for sleep-wake cycles, cognition, eating, mood, and activity.
  • These rhythms play an important role in body temperature, metabolism, blood pressure, and hormone release.
  • Important for DNA repair and cell cycle.
  • Help the body to work properly.

Tips for maintaining a healthy circadian rhythm

Maintaining a healthy circadian rhythm is important for proper body functioning. Here are some tips to maintain a healthy circadian rhythm:

Get outside in the morning

  • When you go outside in the morning and get exposed to the sunlight. These events help reset your internal clock for the day.
  • So, if you have time, get outside, and go for a walk. Sip your coffee on the porch.

Limit nightly screen use

  • The light of the morning and evening works in the same way in your circadian rhythm.
  • The other household light that emits from tablets, lamps, laptops, and smartphones suppresses the production of melatonin hormone because it tricks your brain into thinking that it is still daytime.

Maintain a consistent sleep schedule

  • Try to maintain your consistent sleep to maintain your healthy circadian rhythm.
  • It is important to wake up at the same time every day because the consistent sleep-wake cycle will help to train your clock in your mind to avoid waking up the whole night.
  • Some people continue to sleep the whole weekend and in this disturb your sleep pattern.

Skip the afternoon nap

  • Do not sleep in the afternoon because it disturbs your circadian rhythms.
  • On the other hand, staying active the whole day helps maintain your circadian rhythm by using up your energy storage forms before your prime sleeping time.
  • Taking a nap decreases your ability to fall asleep at night.


Kuhlman, S. J., Craig, L. M., & Duffy, J. F. (2018). Introduction to chronobiology. Cold Spring Harbor perspectives in biology, 10(9).

Dunlap, J. C., Loros, J. J., & DeCoursey, P. J. (2004). Chronobiology: biological timekeeping. Sinauer Associates.

Kleitman, N. (1949). Biological rhythms and cycles. Physiological reviews, 29(1), 1-30.

Rusak, B., & Zucker, I. (1975). Biological rhythms and animal behavior. Annual review of psychology, 26(1), 137-171.

Palmer, J. (2012). An introduction to biological rhythms. Elsevier.

Winget, C. M., DeRoshia, C. W., Markley, C. L., & Holley, D. C. (1984). A review of human physiological and performance changes associated with desynchronosis of biological rhythms. Aviation, Space, and Environmental Medicine, 55(12), 1085-1096.

Volpato, G. L., & Trajano, E. (2005). Biological rhythms. Fish physiology, 21, 101-153.

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