The night worker, the latest layer or insomniac would be at greater risk of cancer than people sleeping early and especially in a completely dark?
As noted by Dr. George Brainard, a professor of neurology at Thomas Jefferson University who has studied for 20 years the effects of light on human biology, humanity has lived without electric light over thousands and thousands years. The human body is made to be active during the sunny hours of the day, and is made to sleep during the dark of night.
The modern world has changed the rules of nature. The man now has an artificial nighttime lighting, especially strong in large urban centers, and business habits have changed, many people in jobs where hours of work may be the night, let alone night owls who stay active and awake until the wee hours of the morning.
This rhythm of life goes completely against the normal biological rhythms, called circadian rhythm. An internal rhythm, alternating between action and rest, wakefulness and sleep. This natural rhythm that is synchronized with the natural light of day and night.
The rupture of a natural law, which is not without consequences
A 2001 study by the Medical School of Harvard, found that nurses who worked over 30 years with a schedule including appearances at night, there was a rate of breast cancer greater than 36% by compared with nurses working days only.
Following this finding, the researchers multiplied the studies and new results were published recently. The results are even more revealing: a 48% increase in cancer among night workers compared to day workers.
Exposure to light during the night would have a very significant impact on the increased risk of certain cancers. The night workers are not the only risk that exists for anyone being exposed during the night, artificial light (this includes the brightness of television screens or computer monitor, the neon signs, etc. .
Intensity and hormone production
Some parts of our brain are particularly occupied a very important task which is to regulate the flow of various hormones in the body. One of these hormones, melatonin is produced when a region of the brain receives the signal of darkness.
Melatonin lowers blood pressure, slows the body functions and has the primary effect of inducing sleep, but this is not his only action.
All body cells have receptors for melatonin, and when present in the bloodstream, the cells decrease their activities. All cells, including cancerous cells.
Research by Steven Hill, Ph.D. Professor at Tulane University, suggests that when melatonin is in contact with a breast cancer cell, it inhibits growth. Indeed, melatonin seems to have a protective effect against various cancers promoted by certain sex hormones (breast, ovaries, testes)
The only cells not to be hampered in their work, by the presence of melatonin, the cells of the immune system, by contrast, melatonin stimulates the action of interleukin-2.
The obvious connection seems to exist between the reduction of melatonin and increased development of cancer, however, is not unanimity of all researchers.
As recalled by the oncologist Marisa Weiss, MD, there are many hormones that act and interact in the body and influence in the development of certain cancers, and it is not easy to determine with certainty the exact influence each of them.
According to Dr. Weiss, it is nevertheless likely that there is a report from the Association melatonin, light and cancer.