Women who regularly work night shifts are 40 per cent more likely to develop breast cancer, according to new research.
Health on Female First
The risk is highest among women who are naturally early risers. But even night owls are in danger.
Researchers found those who work late shifts three times a week for six years are at four times the risk of breast cancer.
It is thought that disruption to the body clock and the resulting changes in levels of the 'darkness' hormone melatonin might be responsible along with sleep deprivation.
The study involved examining the medical records of 18,500 women who worked for the Danish Army between 1964 and 1999.
Dr Johnni Hansen, of the Danish Cancer Society which did the study, said: “The results indicate frequent night shift work increases the risk for breast cancer and suggest a higher risk with longer duration of night shifts.
“Those with morning preference tended to have a higher risk than those with evening preference.”
The study also indicated working up to two night shifts a week had no impact as it may not be long enough to disrupt the body clock.
Disturbing normal sleep patterns is thought to curb the cancer-protecting hormone melatonin. It is produced by the brain in the dark.
The results were based on 692 responses, of which 141 were from women with the disease.
Tagged in Breast Cancer Health Sleep Sleeping Habits