Irregular sleeping patterns have been "unequivocally" shown to lead to cancer in tests on mice, a study suggests. The report, in Current Biology, lends weight to concerns about the damaging impact of shift work on health.
The researchers said women with a family risk of breast cancer should never work shifts, but cautioned that further tests in people were needed.
Mice prone to developing breast cancer had their body clock delayed by 12 hours every week for a year. Normally they had tumours after 50 weeks - but with regular disruption to their sleeping patterns, the tumours appeared eight weeks earlier.
The report said: "This is the first study that unequivocally shows a link between chronic light-dark inversions and breast cancer development."
unequivocally：副詞，表達明確地；毫不含糊地。例句：The Prime Minister, he said, had the party’s unequivocal support.（他說，首相獲得全黨堅定不移的支持。）
lend weight to：片語，使……更重要。例句：This lends weight to the theory that a viable hybrid population was sustained by interbreeding over a long time.（這進一步證實以下理論：雜交後產生的可育雜合群體，可維持相當長的時間。）
be prone to sth/do sth：片語，易於遭受（疾病）的；有……傾向的。例句：I’ve always been prone to headaches.（我常會頭痛。）