To assess the SHC, a valid questionnaire designed in the Health Behavior in School-aged Children (HBSC) study was applied [14]. The questionnaire was fulfilled using a face-to-face interview conducted with students. Participants were asked if they had experienced either any psychological (e.g., feeling low, feeling nervous, difficulty in getting sleep, irritability) or somatic symptoms (e.g., stomach ache, headache, backache, feeling dizzy) in the last six months before the study. The frequency of each sign was asked, as well.

Response options for each symptom were as follows: (i) about every day, (ii) more than once a week, (iii) about every week, (iv) about every month, (v) and (vi) rarely or never. Finally, the responses were categorized as “weekly or more” and “rarely or never.” All questionnaires are provided in Supplementary files.