Light at Night Might Be a Cancer Risk By Ed Edelson, HealthDay Reporter    HealthDayNews -- Could electric light pose a cancer threat?    It might seem like the wildest of paranoid beliefs, but a growing number of scientists suspect it might be true. The reason: Turning on the lights after dark may affect a small number of "clock genes" that play a major role in controlling how cells live, die and function, these researchers suggest...