Hormones: Timekeepers of Our Body

P. Neslihan Taşlı, PhD

P. Neslihan Taşlı, PhD

Stem Cell and Exosome Researcher

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How are you? Are your biological clocks ticking smoothly? Let's delve into the world of circadian rhythms and hormones.

The circadian rhythm is our body’s biological clock, orchestrating numerous biological processes, from our daily activities to sleep and even regulating body temperature1. And the heroes who regulate this rhythm are none other than hormones!

Melatonin is a hormone secreted during the night, controlling our body’s sleep patterns. As dusk approaches, light sensors in our eyes signal the brain, “The day is ending, time to prepare!” This triggers the release of melatonin from a tiny region in the brain called the pineal gland. This hormone is responsible for pre-sleep relaxation and preparing the body for sleep2.

Cortisol is usually secreted in the early hours of the morning, often after waking up. It primes your body for the day ahead, acting as a natural alarm, prompting your body into action3.

GABA regulates nervous system activities and has a calming effect. It reduces stress and aids in the healthy functioning of circadian rhythms4.

Adrenaline and noradrenaline usually kick in during stressful or exciting situations. When the body perceives sudden danger, the adrenal glands release these hormones, accelerating heart rate, increasing blood pressure, and giving the body a sudden burst of energy5.

Serotonin can be secreted throughout the day but tends to peak when exposed to daylight. Sunlight boosts serotonin levels in the brain. This hormone plays a role in balancing our mood, controlling appetite, and establishing sleep patterns6.

Dopamine is the motivation and reward hormone. It boosts our motivation, enhances our sense of vitality, and helps us focus on our goals. It also contributes to the functioning of our body clock7.

Biological clock… 

The timing of these hormone secretions is generally tailored to the body’s needs. Our daily routines, environmental factors, and our body’s biological clock all contribute to the balanced secretion of these hormones, regulating our body’s functions and aiding in maintaining a healthy life.

Of course, the harmony of our circadian rhythm can be disrupted from time to time. Working late into the night or traveling across different time zones can throw our circadian rhythm off balance, leading to issues like insomnia or lack of concentration.

Fortunately, we can fix this! Establishing regular sleep patterns, exercise, and exposure to light throughout the day are crucial for regulating our body clock. This way, we can feel more energetic, focused, and lively.



  1. Pandi-Perumal, S. R., Cardinali, D. P., Zaki, N. F., Karthikeyan, R., Spence, D. W., Reiter, R. J., & Brown, G. M. (2022). Timing is everything: Circadian rhythms and their role in the control of sleep. Frontiers in neuroendocrinology66, 100978.
  2. Sinha, K. (2023). Quantum Sleep Science: A step-by-step system to optimize your sleep increase focus and live energetically. Shashwat Publication.
  3. Ai, T., Gillath, O., & Karantzas, G. C. (2020). The dual function model of attachment security priming: Theoretical framework and empirical evidence. International Journal of Environmental Research and Public Health17(21), 8093.
  4. He, B., Chen, Y., Yu, S., Hao, Y., Wang, F., & Qu, L. (2022). Food plant extracts for sleep-related skin health: mechanisms and prospects. Food Bioscience, 101951.
  5. Madazimova, K. T., Mambetalina, A. S., & Isatayeva, B. B. (2023). Stress as a psychological phenomenon.
  6. Suarez-Trujillo, A., Hoang, N., Robinson, L., McCabe, C. J., Conklin, D., Minor, R. C., … & Casey, T. M. (2022). Effect of circadian system disruption on the concentration and daily oscillations of cortisol, progesterone, melatonin, serotonin, growth hormone, and core body temperature in periparturient dairy cattle. Journal of Dairy Science105(3), 2651-2668.
  7. Rowe, M. (2022). The Vitality Mark: Your prescription for feeling energised, invigorated, enthusiastic and optimistic each day. Gill & Macmillan Ltd. 

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The information and statements on our website are not intended to guide individuals towards medical diagnosis and treatment. Please consult with your doctor for medical diagnostic and treatment procedures. The contents are shared for informational purposes only, derived from scientific studies prepared by EMC Medya Yayıncılık Ticaret Ltd. Şti.’s researchers, consultants, and authors/scientists, as well as compilations from publicly available publications. Our texts do not contain health statements related to medical diagnosis or treatment

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