A new study suggests that exposure to dim light at night may make a common drug for breast cancer less effective.
Researchers at Tulane University say resistance to the drug tamoxifen is a growing problem among patients whose breast cancer tumors are fueled by hormones. Scientists say exposure to dim light at night made the breast cancer tumors resistant to tamoxifen.
However, scientists say the negative effects of the light were overcome by giving rats a melatonin supplement during the night.
Researchers say night-time exposure to even dim light may cause tumors to become resistant to tamoxifen by suppressing melatonin production.