The rising trend of breast cancer both in developed and developing countries is a real threat challenging all efforts to screening, prevention and treatment aspects to reduce its impact. In spite of modern preventive strategies, the upward trend of breast cancer has become a matter of great concern in both developed and developing countries. Chittaranjan National Cancer Institute is a premier regional cancer institute in eastern region of India catering to a large number of cancer patients every year. A pilot case control study of fifty breast cancer patients and 100 matched controls was conducted during 2013 to evaluate the effects of habitual factors like working in night shift, not having adequate sleep, and not sleeping in total darkness on breast cancer of women. The study revealed that not sleeping in total darkness was associated with higher odds of outcome of breast cancer of women. This positive correlation can play a vital role in formulation of preventive strategies through life style modification.