Study of night-shift workers links men’s sleep habits to cancer risk

Wuhan, China – Male night-shift workers who do not nap during the day or have worked the night shift for more than 20 years – as well as those who average more than 10 hours of sleep per night – may have a greater risk of developing cancer, according to a study from Huazhong University of Science and Technology.

Researchers reviewed data from approximately 27,000 men who had retired from the auto manufacturing industry, using a questionnaire to examine how working nights, napping during the day and extended sleep at night impacted the risk of cancer.

Results showed:

• Men who worked the night shift for more than 20 years had a 27 percent higher risk of cancer.
• Night-shift workers who did not take daytime naps had double the cancer risk of those who napped for up to 30 minutes.
• Men who slept more than 10 hours per night had a 40 percent increase in cancer risk.

Additionally, men with at least two of the studied sleep habits had a 43 percent higher risk of cancer and a more than twofold increase in cancer mortality compared with those with who had none of the habits.

The study was published online Aug. 25 in the journal Annals of Medicine.