Shift Work, Light at Night, and Breast Cancer on Long Island, New York

In a study of 1,161 women, overnight shift workers showed a lower risk of breast cancer with an odds ratio of 0.55.

• Breast cancer was not associated with overall shift work (odds ratio = 1.04) or evening shift work (odds ratio = 1.08).
• Women who frequently turned on lights at home during sleep hours had an increased risk of breast cancer (odds ratio = 1.65).
• The results suggest a potential link between residential light-at-night exposure and breast cancer risk, although response biases could influence these findings.
• Overall and evening shift work did not significantly factor into breast cancer risk, while overnight shift work was associated with reduced risk.

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