Does working the night shift increase the risk of cancer?

Answers from Timothy J. Moynihan, M.D.

Various studies have suggested an association between night shift work and an increased risk of cancer, perhaps due to altered circadian rhythms or lower levels of melatonin in the blood. Still, these studies haven't proved that night shift work causes cancer. In fact, many of the studies linking shift work and cancer have serious limitations — including difficulty controlling for known cancer risk factors, such as smoking.

If you work the night shift, switching to the day shift isn't likely to change your overall cancer risk. However, you can take other steps to help prevent cancer. For example:

  • Don't use tobacco.
  • Eat a healthy diet.
  • Maintain a healthy weight.
  • Include physical activity in your daily routine.
  • Protect yourself from the sun.
  • If you choose to drink alcohol, do so only in moderation.
  • Ask your doctor about vaccines for certain viral infections, such as hepatitis B and human papillomavirus (HPV).

Also remember the importance of regular self-exams and professional screening for various types of cancer. Early detection increases the odds of successful treatment.

Dec. 02, 2010