The survey revealed that 36 percent of students felt under great pressure while 12 percent thought themselves worthless.

The poll conducted by Lingnam University's Pan Sutong Shanghai-Hong Kong Economic Policy Research Institute interviewed 3,500 primary and secondary students and 150 teachers from May to August.

The happiness index of students fell from 6.85 to 6.77 compared to last year.

But the school life, education and happiness index increased from 3.81 to 3.87 out of five,.

This index is designed to indicate if students feel inspired in loving and caring for family and friends and learning to face obstacles positively through school activities.

The study showed in-person classes were some of the most effective means for life education. The researchers noted that the pandemic has continued to put students under great stress and led to a drop in their happiness levels.

Patrick Ip Pak-keung, a clinical associate professor in the Department of Pediatrics and Adolescent Medicine at the University of Hong Kong, said: "Although the suspension of face-to-face classes has effectively stopped the spread of Covid among schools, students sacrificed a lot in the past two to three years."

He said parents should encourage their children to participate in more extra curricular activities as the local pandemic appeared more contained.

Ip also said it is important to foster an all-round development for children both mentally and physically. Harmonious parent-child relationships were proven to increase children's self-confidence.

The survey also showed that bullying cases appeared to occur more frequently around primary four to six students.

On that, Ip reminded teachers and parents to pay more attention to bullying cases.