Feng Lei, a specialist from the Dalian Psychological Society with a doctorate in applied psychology, is positive about the effects of the trend.

"People are happy when they are helping others," she said. "When dressing trees in sweaters and making them warm and cute, it's actually about bringing warmth to oneself. Many people hugging the trees in sweaters are also warming themselves," Feng said.

She believes that dressing trees in sweaters is a novel and creative idea, and a way for people to enthusiastically express their love for their city.

Behind the popularity of this activity is a collective unconscious need for warmth from others, especially during challenging times, and a psychological need to be cared for and comforted, experts said.

Researcher Cao Yixia from the Institute of Applied Economics of the Shanghai Academy of Social Sciences told Shanghai Observer news portal that young people's fondness for personifying everything is a projection of a desire for companionship. This is done in the context of a relative lack of social interactions and contact with neighbors, Cao said.

An attending physician in the field of mental health told Shanghai Observer that such phenomena are all rooted in psychology.

"What people find fun is that it uses a contrast, turning buildings into people, turning things without warmth into warm things," he said.

In his view, this is just "a little game" that may not be popular after a while when new trends have soon emerged. In fact, turning city buildings into ice sculptures was popular on social media when the "sweater dressing" trend was still gaining popularity, he said.