Some studies suggest that not getting enough sleep can increase your risk of developing cancer. According to Breastcancer.org, a study published in August 2012 in the issue of Breast Cancer Research and Treatment found a significant link between lack of sleep and raised re-occurrence of breast cancer in women. In this study, researchers looked at 101 records of women diagnosed with early-stage, estrogen-receptor-positive breast cancer. They looked at their Oncotype DX scores (which analyze a group of 21 genes and help doctors assess someone's risk of developing early-stage, estrogen-receptor-positive breast cancer and its likelihood of re-occurring. They also compared it to how many hours of sleep each woman reported. Researchers found that higher Recurrence Scores were linked to fewer hours of sleep per night (especially in postmenopausal women). While the link is not yet fully understood- some doctors think it has to do with low melatonin levels. Lower melatonin levels may lead to patterns of breast cell growth and repair that make breast cancer more likely to develop. Sleep deprivation can also cause low-grade inflammation- which is often linked to many types of cancers.