Circadian rhythm

Circadian disruption has been classified as probably carcinogenic to humans by the World Health Organization’s International Agency for Research on Cancer.  So what is it?

The circadian clock is the body’s biological clock that controls the daily rhythm of functions such as sleep, body temperature, and metabolism. It is an area in the brain that senses environmental cues (eg light, temperature) and communicates information to other parts of the body. It controls the “on” and “off” cycle of many important systems in the body, eg endocrine system.  Relatively recent changes to our environment such as artificial lighting, the lighting on our phones, rotational shift work, night work, etc, can cause disruption of the circadian clock and cause different systems within the body to get stuck “on” or “off”.  

Sleep/wake cycles are closely linked with the circadian system, and global trends indicate that these too are increasingly subject to disruption. A large proportion of the world’s population is therefore at increased risk of environmentally driven circadian rhythm and sleep disruption. A minority of individuals are also genetically predisposed to circadian disruption and sleep disorders. The consequences of disruption to the circadian system and sleep can cause the right conditions for numerous medical conditions to occur, some of which may also be made worse by dietary choices.

The medical conditions linked to a disruption of the circadian rhythm and sleep include diabetes type 2, impaired glucose tolerance, abdominal obesity, high blood pressure, high serum triglycerides, and low levels of HDL (good) cholesterol. This in turn can lead to the development or exacerbation of cardiovascular disease.  A disruption of the circadian rhythm is also thought to be a factor causing the development of different types of cancer.

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