Darkness, it turns out, can also reduce the intensity of emotional responses and can promote unethical behaviors, including cheating and selfishness. These findings suggest that the low levels of illumination commonly found in restaurants, cinemas, nightclubs, airplanes, and along highways could elevate the risk of a number of unhealthy or even dangerous behaviors, including failure to wash one’s hands, sexual promiscuity, or an increased likelihood of speeding or drunk driving. Perhaps there is, after all, reason to fear the dark.