Conversely, women who interrupt their melatonin production by working night shifts appear to be at increased risk for breast cancer.35 Even living on a particularly brightly lit street may affect the risk. Studies comparing nighttime satellite photos against breast cancer rates have found that people living in brighter neighborhoods tend to have a higher breast cancer risk.36,37,38 Therefore, it’s probably best to sleep without any lights on and with the blinds down, though the evidence to support these strategies is limited.39
