Graveyard shift linked to cancer risk

GENEVA, Switzerland, Nov. 30 (UPI) -- The Swiss-based World Health Organization says people who work at night may have a higher risk of developing cancer.

The results of an analysis by the WHO's International Agency for Research on Cancer, published in the December issue of the journal Lancet Oncology, suggests exposure to light on the night shift poses a similar cancer risk as agents such as anabolic steroids, ultraviolet radiation and diesel engine exhaust, the Scotsman newspaper said Friday.

The IARC plans to classify night shift as a "probable" carcinogen.

Several studies in recent years have found that women who work nights for long periods of time are more prone to breast cancer, animals whose days and nights are switched have more cancerous tumors and that men working at night may have an increased rate of prostate cancer.

Scientists suspect shift work disrupts the circadian rhythm and reduce the production of the hormone melatonin, which may raise the chance of developing cancer. Sleep deprivation also leaves the immune system vulnerable, the newspaper said.