Circadian Rhythm and Its Role in Cancer
Introduction:
From the rising and setting of the sun to the ebb and flow of our energy levels throughout the day, our bodies follow a natural rhythm known as the circadian rhythm. This innate biological clock governs various physiological processes, including sleep-wake cycles, hormone production, and metabolism.
However, recent scientific discoveries have shed light on an intriguing aspect of the circadian rhythm: its intricate relationship with cancer. In this blog post, you’ll learn the fascinating connection between our internal clocks and the development, progression, and treatment of cancer.
Understanding Circadian Rhythm:
The circadian rhythm refers to the roughly 24-hour cycle that regulates the timing of biological processes in living organisms. This internal clock is primarily controlled by a small region in the brain called the suprachiasmatic nucleus (SCN), which receives signals from light-sensitive cells in the retina. The SCN synchronizes the body's functions with the day-night cycle, ensuring optimal performance and adaptation to the environment.
Circadian Rhythm Disruption and Cancer Risk:
Disruption of the circadian rhythm, such as through shift work, irregular sleep patterns, or exposure to artificial blue light from screens and lighting, has been linked to an increased risk of cancer. Epidemiological studies have shown a higher incidence of breast, prostate, and colorectal cancers among night shift workers. This association can be attributed to several factors.
Melatonin and Cancer Suppression:
Melatonin, often referred to as the "hormone of darkness," is a key player in the regulation of the circadian rhythm. It is produced by the pineal gland during the night and helps to promote sleep. Additionally, melatonin exhibits powerful antioxidant and anti-inflammatory properties, making it a potent cancer-fighting molecule.
Studies have shown that exposure to light at night suppresses melatonin production, disrupting the body's natural sleep-wake cycle. The reduced levels of melatonin have been associated with an increased risk of developing certain types of cancer, including breast and prostate cancer. Melatonin's role in cancer prevention lies in its ability to inhibit tumor growth, regulate cell division, and modulate the immune system.
Clock Genes and Tumor Suppression:
Clock genes are a group of genes responsible for maintaining the circadian rhythm at the cellular level. These genes orchestrate a complex network of molecular interactions that synchronize various cellular processes. When the circadian rhythm is disrupted, the expression of clock genes can be altered, leading to cellular dysfunction and an increased susceptibility to cancer.
Furthermore, clock genes interact with other key cellular pathways involved in DNA repair, cell division, and cell death. Disruption of these clock-controlled processes can result in genomic instability and the accumulation of DNA damage, contributing to the initiation and progression of cancer.
How to optimise your circadian rhythm?
Maintain a Consistent Sleep Schedule: Try to go to bed and wake up at the same time every day, even on weekends. Consistency helps regulate your internal clock and promotes better sleep quality.
Get Exposure to Natural Light: Spend time outdoors during the day, especially in the morning. Natural light exposure helps regulate your circadian rhythm and promotes alertness during the day.
Limit Exposure to Artificial Light: Try to minimize exposure to bright screens from electronic devices like smartphones, tablets, and computers throughout the day, but especially at night. Consider using blue light filters for your screens or blue light blocking glasses.
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Create a Sleep-Friendly Environment: Make your bedroom conducive to sleep. Keep the room dark, quiet, and cool. Use blackout curtains, earplugs, or white noise machines if necessary.
Avoid Stimulants Close to Bedtime: Limit consumption of caffeine and avoid heavy meals, nicotine, and alcohol close to bedtime. These substances can interfere with your sleep quality and disrupt your circadian rhythm.
Establish a Relaxing Bedtime Routine: Develop a pre-sleep routine to signal to your body that it's time to unwind and prepare for sleep. Engage in activities like reading, taking a warm bath, or practicing relaxation techniques.
Exercise Regularly: Engage in regular physical activity, but avoid intense exercise close to bedtime as it can make it harder to fall asleep. Aim for moderate exercise earlier in the day, which can help regulate your sleep-wake cycle.
Limit Daytime Napping: If you need to nap, keep it short (around 20-30 minutes) and avoid napping late in the day, as it can interfere with your nighttime sleep.
Manage Stress: High levels of stress can disrupt your circadian rhythm. Find healthy ways to manage stress, such as practicing mindfulness, deep breathing exercises, or engaging in activities you enjoy.
Conclusion:
The connection between the circadian rhythm and cancer is a captivating area of research that has the potential to revolutionize our understanding and management of this complex disease. Disruption of the circadian rhythm can increase the risk of cancer development, while maintaining a healthy rhythm and promoting melatonin production may have protective effects.
Further reading:
Innominato, P. F., Roche, V. P., & Levi, F. A. (2013). Circadian timing in cancer treatment: The biological foundation for an integrative approach. Integrative Cancer Therapies, 12(4), 267-287.
Papagiannakopoulos, T., Bauer, M. R., & Davidson, S. M. (2016). Circadian rhythms and metabolism in cancer. Advances in Drug Delivery Reviews, 62, 1347-1355.
Filipski, E., & Levi, F. (2009). Circadian disruption in experimental cancer processes. Integrative Cancer Therapies, 8(4), 298-302.
Stevens, R. G., Hansen, J., Costa, G., Haus, E., & Kauppinen, T. (2011). Aronson KJ, et al. Considerations of circadian impact for defining 'shift work' in cancer studies: IARC Working Group Report. Occupational and Environmental Medicine, 68(2), 154-162.
Ballesta, A., Innominato, P. F., Dallmann, R., Rand, D. A., & Lévi, F. A. (2017). Systems chronotherapeutics. Pharmacological Reviews, 69(2), 161-199.
Mormont, M. C., & Lévi, F. (2003). Circadian-system alterations during cancer processes: A review. International Journal of Cancer, 106(3), 273-280.
Fu, L., & Lee, C. C. (2003). The circadian clock: pacemaker and tumour suppressor. Nature Reviews Cancer, 3(5), 350-361.
Innominato, P. F., Giacchetti, S., Bjarnason, G. A., Focan, C., & Lévi, F. (2009). International consensus on the implementation of centralised European time for cancer patients (CETC). European Journal of Cancer, 45(18), 3166-3171.
