Night-shift work, sleep duration, daytime napping, and breast cancer risk

Night-shift work is associated with an increased risk of breast cancer, with an odds ratio of 1.34.

• Women with shorter sleep duration of 6.0 hours or less have an increased breast cancer risk, with an odds ratio of 1.53.
• Women who sleep 9.0 hours or more also face an increased risk of breast cancer, indicated by an odds ratio of 1.59.
• Daytime napping is associated with a reduced risk of breast cancer among night-shift workers, with an odds ratio of 0.57.
• No significant association between daytime napping and breast cancer risk was observed among women who never worked night shifts.
• The combined effects of night-shift work and longer sleep duration significantly increase breast cancer risk, with an odds ratio of 3.69.

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