Much of the body’s biological processes can seem complex; however, one particular piece of our health is essential to consider for day-to-day wellness: our circadian rhythm. This internal clock governs our physiological functions, such as hormonal releases, cellular activities, and metabolic processes. Aside from its many responsibilities, the circadian rhythm plays a pivotal role in maintaining hormone and thyroid health. Today, we will uncover the secrets of our circadian rhythm and understand why it is vital for our overall well-being.
Understanding Your Circadian Rhythm
The circadian rhythm is a 24-hour cycle that regulates various physiological processes, aligning them with the day-night cycle. The master clock governs it in the brain– the suprachiasmatic nucleus (SCN) – this internal timekeeper responds to external cues, primarily light and darkness, to synchronize the body’s functions with the external environment.
Hormonal Balance:
One of the circadian rhythm’s primary responsibilities is regulating hormone release. The circadian clock coordinates and maintains the required reproductive activities in the body; this is governed by the hypothalamic-pituitary-gonadal (HPG) axis (1). Our hormones act as messengers, transmitting signals to different body parts. Estrogen and progesterone have additional responsibilities throughout each phase of our cycle and impact our circadian clock. In circadian rhythms, hormones follow a daily routine, influencing everything from sleep-wake cycles to metabolism. However, any abnormal environmental stimuli contribute to disorders of the female reproductive cycle (1).
This is why it is essential to ensure that you are mindful of your light intake throughout the day. We have to tell our bodies in the morning that we should have a rise in cortisol. Throughout the day, it is essential to be mindful of exposure to artificial light sources; taking light breaks can be very helpful as it programs our brain to know when it should be to wind down and increase melatonin production for good sleep. Overexposure to artificial light throughout the day keeps our cortisol production high, telling our brain to stay awake as a survival response and keeping us alert at all times; this, however, is very depleting and harmful to our long-term health.
Thyroid Relationship:
The circadian rhythm also exerts an influence on our thyroid function. The thyroid gland is crucial in metabolism regulation and is intertwined with the circadian clock. Prolonged circadian disruptions may contribute to conditions such as hypothyroidism or hyperthyroidism.
- Thyroid-Stimulating Hormone (TSH):
- TSH stimulates the thyroid gland to produce thyroid hormones; it follows the circadian rhythm. These levels typically peak during the early morning hours to align with the body’s increased metabolic demands and rising cortisol levels as it prepares for the day. This rhythmic release ensures an optimal balance of thyroid hormones for energy production and metabolism.
- Thyroid Hormones (T3 and T4)
- These also exhibit circadian fluctuations. T3 and T4 levels are orchestrated to meet the body’s changing demands throughout the day, regulating energy expenditure, temperature regulation, and overall metabolic activity.
The circadian rhythm is the conductor of our body’s symphony, ensuring that hormones and thyroid function harmonize with the natural rhythm of day and night. Recognizing the importance of this internal clock and adopting lifestyle practices that support its integrity can pave the way for optimal hormone and thyroid health. As we navigate the demands of modern life, let’s not forget that this delicate balance sustains our well-being.
(1) Shuyi Shao, Huanqiang Zhao, Zhiying Lu, Xiaohong Lei, Ying Zhang, Circadian Rhythms Within the Female HPG Axis: From Physiology to Etiology, Endocrinology, Volume 162, Issue 8, August 2021, bqab117, https://doi.org/10.1210/endocr/bqab117
