It has been long suggested by researchers that being exposed to too much light at night disrupts crucial hormones and raises the chance of developing breast tumours . Women particularly those who work night shifts like nurses and airhostesses are considered to be of particularly risk.
For the first time now scientists from the American National Cancer Institute and National Institute of Environmental Health Sciences, have demonstrated that long exposure to artificial light could certainly be cancerous. The researchers claim that they could now have an explanation for the rising levels of breast cancers in rich countries, where the risk of developing cancer is five times higher than in underdeveloped countries.
It has been reported that breast cancer is the most common cancer in women in the UK that affects one in nine women at some point in their lives. Reports also show that around 41,000 women are diagnosed each year and each month in the UK and more than 1,000 die from the disease. The American researchers have now shown that exposure in the night to artificial light could stimulate the growth of human breast tumours by directly suppressing the levels of a key hormone 'melatonin'.
Explaining that melatonin is secreted by the pineal gland during nighttime and it helps to regulate the person's sleep-wake cycles, but they said that light, however, would make the body to feel that it is daytime and stops it from producing it. The researchers proved their theory by grafting human breast cancer tumours on to rats, by pumping blood samples from women through the developing tumours.
They stated that the blood had been collected under three different conditions, during the day, in the early hours of the morning and after being exposed to light at night. The researchers found that the blood taken in darkness slowed the growth of the cancers by 80%. Whereas, the blood taken after exposure to light appears to stimulate the growth of tumour.
Dr David Blask, a lead researcher of the study said that it was the first proof to ever have been noted that light is indeed a risk factor for cancer. He also added: 'Evidence is emerging that disruption of a person's body clock is associated with cancer in humans, and that interference with internal timekeeping can tip the balance in favour of tumour development.'
Professor George Brianard, of the Thomas Jefferson University in Philadelphia, stated that humans have evolved on the planet without electric light over thousands of thousands of generations. Stating that the body is designed to be alert and awake during the daytime hours and to sleep at night he explained that now a days, people are increasingly following a 24/7 lifestyle that isn't in harmony with the biological design of the body.
It was explained that if the link between tumour growth and light is confirmed by more studies, it could result in a change in working patterns. There could be a definite onus on the manufacturers of lighting systems to develop products that would be more natural and similar to normal daytime.