A recent study has shown that women are at a higher risk of breast cancer if they regularly work night shifts.
The study, from the Danish Cancer Society, shows that women working more than two night shifts a week increase their chances of developing breast cancer by more than half compared to those working in a regular nine to five job. The study looked at over 18,000 women who worked for the Danish army between 1964 and 1999 and showed that those who did work at night had a 40% increased chance of breast cancer compared to those women who worked in the day and that risk increased substantially if they worked night shifts at the rate of three or more a week for at least six years.
It is not categorically known why this should be the case, but scientists believe that a hormone in the body which can prevent tumours, becomes disrupted by exposure to light during night time. Therefore, occasional night working does not present a significant risk, but frequent night shifts apparently do.
Melatonin is the hormone which has been shown to suppress tumours and it is principally known for dictating the natural cycles that regulate sleeping patterns and it is thought that very low levels of the hormone, caused by exposure to light during night hours, may promote tumour growth.
A cancer charity, Breakthrough Breast Cancer, said that night shifts alone may not be responsible, but it may be a contributory factor, added to by such factors as lack of regular exercise or an unhealthy diet.
http://www.dailymail.co.uk/health/article-2151351/Breast-cancer-link-wor...
