oa Disruption of circadian rhythm increases the risk of cancer, metabolic syndrome and cardiovascular disease

Incidents of non-communicable diseases (NCD) like cardiovascular diseases, cancer, diabetes, and chronic respiratory disease have increased dramatically and are currently the leading causes of death worldwide. Their rising incidents coincide with the dramatic changes in industrialization and development of societies over the past few hundred years. Therefore, current lifestyle practices should be further explored to uncover novel risk factors for certain cancers (i.e. colon, prostate, and breast cancer), metabolic syndrome (i.e. diabetes and obesity), and cardiovascular disease (i.e. coronary artery disease). This review discusses how a disruption of the “biological clock” or circadian rhythms could be involved in the development of these diseases as circadian rhythms control multiple physiological processes such as wake/sleep cycles, hormonal levels, body temperature, metabolism, and immune system.

Several environmental factors that disrupt circadian rhythms can be identified including exposure to artificial light and electromagnetic (EM) waves, unbalanced diet and night shift work. The mechanisms of how these “chronodisruptors” are associated with NCDs will be discussed. Furthermore, the involvement of genetic factors in the disturbance of circadian rhythms and predisposition to NCDs will be highlighted.

Overall there is strong evidence from animal models and epidemiological studies underlining that circadian disruption is a significant player in several diseases particularly the multifactorial diseases that pose a significant public health challenge in contemporary society. A circadian disruption-based model of cancer, metabolic syndrome and cardiovascular disease etiology can be proposed. But, to fully understand the complex interactions of the different components in the network of disease development due to disruption of circadian rhythms, more investigations are needed to unravel the causal relationship between modern lifestyle, circadian rhythm disruption and complex disease. This summary will help to better understand the mechanisms and aid the development of new methods and policies to lower incidence/death rates.