In the 20th century, Dutch psychologist Nico Frijda noticed something strange. Some patients went to hospitals every 28 days for headaches and mental fatigue (精神疲劳). He described this period as the “law of emotions (情绪定律)”. It shows that people’s psychological changes are cyclical (周期性的). The following are four possible psychological status (心理状态) changes that we might experience during the NCP outbreak, according to this theory.