Short sleep duration and breast cancer

This article discusses research showing an association between post-menopausal women with short sleep durations and aggressive breast cancer. There was no association between the aggressiveness of the cancer and sleep duration in pre-menopausal women. The researchers obtained sleep duration by asking the women how long they slept on average, and this method is not the most accurate. It's not clear why the link between short sleep duration and aggressiveness of breast cancer - it could be that insufficient sleep causes our bodies to be in a chronically inflamed state, which perhaps may be more advantageous for certain tumors. More studies are needed to see if better or more sleep could reduce the aggressiveness of breast and other cancers.