Experts from the World Health Organization’s International Agency for Research on Cancer (IARC) held a panel meeting last month that will include night work as one of the cancer-causing factors in the December issue of The Lancet Oncology.
The study is based on the results of a follow-up survey of nurses and flight attendants who regularly work night shifts, as it showed that the incidence of breast and prostate cancers was higher among women and men who worked overnight than among those who worked daily.
Since this study needs to be done on a broader night shift population. So given the questionable nature of the findings, the International Agency for Research on Cancer has used the label “probable carcinogenic factor” as a sign of caution.
Possible causes of night shift cancer
1. Night shift leads to a decrease in secretion of melatonin, which inhibits tumor production;
Night shift disrupts the normal biological clock of human body, which should be sleeping when it is working, and melatonin, which can inhibit tumor production in human body, is generally secreted at night, and light will inhibit melatonin secretion. Scientists believe that low melatonin levels can increase the risk of cancer development.
2. Night shift causes sleep deprivation, which affects the normal function of the immune system; people who work at night are prone to sleep disorders, and when they should sleep during the day, they cannot sleep because of excitement, resulting in sleep deprivation. Sleep deprivation will make the immune system more vulnerable and less able to fight against potential cancer cells.
This is another possible factor for the increased risk of cancer.
3. Disruption of the biological clock also affects cell division, DNA repair and other essential body functions.
The human body is a complex machine, and many studies have shown that the time of sleep at night is an important stage for the body to repair, so disruption of this time may affect the body to repair, and cause health risks.
4, black and white life will affect the endocrine disorders.
Long-term “black-and-white” life will cause the body’s life rhythm to be disrupted, the neuroendocrine system dysfunction, estrogen, progesterone imbalance. The high incidence of tumors in women is related to estrogen and progesterone, and the imbalance in the secretion of these two hormones may lead to the occurrence of uterine fibroids, endometrial cancer and breast cancer.
Take breast cancer as an example, long term stimulation by adverse factors such as staying up late at night may lead to endocrine imbalance and decrease in immunity, which may reduce the production and release of thymosin from thymus gland and decrease the ability of lymphocytes and macrophages to monitor and phagocytose mutated cells in the body, making it easy for cancerous lumps to occur.
The head of the IARC’s carcinogen classification department, Coriano, said there are enough samples to show that the incidence of cancer in the night shift population is increasing, but “we cannot exclude other possible (carcinogenic) factors.
Alternating day and night shifts is more dangerous than overnight shifts
The question is how to adjust your biological clock,” said Aaron Blair of the National Cancer Institute. If you work night shifts all the time, you’re less likely to have a disruption (of your biological clock) than if you work shifts regularly.” Alternating day and night shifts is more likely to lead to biological clock disruptions and endocrine disorders.
Supporting evidence for the study
Stevens, a cancer epidemiologist at the University of Connecticut Health Center, was one of the first scientists to focus on the relationship between overnight shifts and cancer. In 1987, Stevens published a paper that linked nighttime light to the development of breast cancer. Previously, Stevens noted that the incidence of breast cancer had suddenly spiked in industrialized societies since the 1930s. In that era, night work was seen as one of the hallmarks of industrial development.
Stevens’ deduction was a surprise to most scientists at the time. In recent years, however, studies have found that women who work night shifts are indeed more likely to develop breast cancer. Animal studies have also shown that night and day reversals make animals more likely to develop tumors and die prematurely.
Some studies have also shown that the incidence of prostate cancer is relatively high among men who work overnight.
Remedial measures
1, try to avoid the “black and white” life. This is the most crucial point.
2, strengthen nutrition, eat more digestive food;
3, sleep to ensure that, during the day to catch up on sleep, try to create a quiet, dark environment, this dark environment is very important.
4, if fully adapted to the “black and white” life, the endocrine return to normal, the adverse effects on the body will be reduced.
5, women who often work at night, every 3 to 6 months to the hospital to check the body, especially the level of female hormones. If the endocrine disorder is detected, you must seek medical attention in time, and it is best to choose Chinese medicine to regulate. If necessary, hormone supplements can be taken, but only under the guidance of a doctor.
Possible cancer-causing factors listed by the World Health Organization: smoking or chewing tobacco, alcohol, betel nut, ultraviolet light, car exhaust, anabolic steroids, etc.