अँधेरे में सोइए, कैंसर से बचिए Missing Dark Promotes Cancer

Author : Dr. P. D.GUPTA

(Former Director Grade Scientist, Centre for Cellular and Molecular Biology, Hyderabad, India)


In modern industrialized societies cancer is fuelled by the excesses of modern life. Thanks to Thomas Alva Edison, who extended our working hours by putting light during natural dark hours? 

Researchers surveyed and found that “the increased risk in BC (breast cancer) in recent decades in industrialised countries results in part from increased exposure to Light at night ”. More so the increased risk of BC in nightshift workers gone beyond proportion. In the survey we made, found out that “Blind woman has minimum risk of developing BC”We miss dark and suffer the consequences. 

Three great scientists have to be remembered in the area of light, namely, Sir C V Raman, Prof. Albert Einstein and Thomas Alva Edison who revolutionized physics, chemistry and biology of light. This makes it to reach almost every place on the earth, since it is essential for life. But excess use of this energy during night adversely affects human physiology and therefore is harmful. 

Light and dark cycles – Essential for life 

Ninety eight percent of sunlight enters in our body through the eyes, and 2% through the skin. Light acts on our body on an ongoing basis to power the cells, regulate biological clock and produce hormones, affect metabolism. When enough light is not there, all body functions start diminishing, and cause depression and adversely affect immune system. Earlier we studied the effects of day light in born blind rats and concluded that the   eye   serves at least two functions: 

1.   To see and recognition object. 

2. Regulates circadian rhythms, instructs the pineal gland to produce the appropriate hormones namely, serotonin during daylight; melatonin in the dark night.  

Natural light has been used to treat depression, jaundice of new born from times immemorial. However, now different intensities of artificial light are used to treat many diseases. With the advent of electricity, day light is extended and darkness is 

replaced by yellow incandescent light. The industrial revolution resulted in the fluorescent (“daytime” spectrum bulbs) replacing incandescent bulbs at homes and workspaces. Now fluorescent bulbs and screens are replaced by LED light. 

Before the advent of artificial light our life was synchronized with 12 hours day/12 hour night periods. The use of light at night to extend the day, dismissed natural life style which resulted in different disease. All these lighting systems predisposes us to more of blue light which inhibiting synthesis of melatonin, altering our circadian sleep and hunger rhythms, changes in alertness and possible psychological and disease-susceptibility disturbances. In the recent past these “blue light” effects have focused a significant research attention discussed as a public health issue. 

Epidemiological studies suggest that continued (24 hours) exposure to light be associated with an increased risk of breast, prostate cancers especially, hormone dependent cancers.  

Topography, photoperiod and breast cancer 

Major source of light on the earth is the sun. In the equatorial region, sun shines only for 12 hours and the rest 12 hours is the dark period, but on poles it is a different story. There are countries around the poles where night is missing. The sun shines continuously for 23/24 hrs. Therefore the physiology of the organisms which is aligned with light gets disturbed. The human settlements increased after the advent of artificial light in the zones where sunshineis very much extended or reduced. In such regions, survey results also showed a several-fold difference in the incidence of breast cancer (BC) between countries closer to the poles than to the equator has been recorded. 

Night light and shift workers 

In the Night shift workers melatonin production is very much reduced, and they have higher risk of developing cancer. Artificial light at night disrupting the natural melatonin- estrogen balance was linked with the increase in hormone regulated BC among women. The increased cancer risk has been reported in nurses, radio-telephone operators, flight attendants, and women employed in the enterprises in which 60% of employees work at night. A study involving members of the Californian Teachers found an increased risk of developing BC in women living in areas with the highest outdoor light at night, estimating the impact of indoor and outdoor light at night. Risk of developing BC increased in women who worked night shifts for more than five years especially those who are regularly engaged in night work for at least four years prior to their first pregnancy, before their breast had fully developed.     

Predictions were made long ago that women working a non-day shift would be at a higher risk of developing BC compared to the day-working women. Total revamping the shift work schedule taking all appropriate and effective measures against proven links to BC with health care system for women is still wanting worldwide. Proper education needs to be given on health activities, such as, campaigns to improve the understanding of the consequences and risks of night shift working pattern so as to minimize the development of BC. Night shift working system has also been linked with prostate cancer in men similar to BC in women.   

Light at night is now clearly a risk factor for BC. The breast tumours are awake during the day, and melatonin puts them to sleep at night if artificial light is added to the night environment, the cancer cells become insomniacs. (The author has his own study and views)