H college students recruited from six cities in the Guangdong Province
H school students recruited from six cities inside the Guangdong Province through a threestage stratified group sampling approach. For the first stage, the cities were divided into 3 strata in accordance with their economic level, and two cities had been chosen in every single stratum. For the second stage, two schools (six junior higher schools, four senior high schools and 2 vocational high schools) have been randomly selected from all the schools in each and every city. For the third stage, 2 classes had been randomly chosen from each and every grade inside the chosen schools. All students (a total of 25,655) in the chosen classes had been asked to take part in this study and offered informed consent voluntarily. A total of 23,877 valid questionnaires 
have been collected, resulting inside a valid price of 93.36 .Data CollectionTo safeguard the privacy with the students, anonymous questionnaires have been administered by educated interviewers in the absence from the teachers (to avoid any potential details bias). The students were expected to fill out the questionnaires during class time.Ethical StatementThis study received approval in the Sun YatSen University, College of Public Overall health Institutional Evaluation Board. All participants were fully informed from the objective of your study and have been invited to participate voluntarily. Written consents had been obtained from each participant and their parents.MeasuresDemographic characteristics. The demographic questionnaire elicited data on age, gender, grade, economic status, academic pressure, relationships with families, classmates and teachers, and smoking. Loved ones economic status was measured by asking the student’s perception of their family’s present status (rated from good to terrible). Academic pressure was captured by a single item primarily based around the student’s selfrating from low to high. Relationships with households, classmates and teachers were assessed based on the student’s selfrating from very good to poor. GSK0660 site smoking was assessed by asking, “Did you smoke at least 1 cigarette per week” Sleep high quality. The students’ sleep good quality was measured by the Chinese version of PSQI, which consists of 9 products creating 7 components: subjective sleep excellent; sleep latency; sleepPLOS A single DOI:0.37journal.pone.02602 March 26,three Bullying as a Threat for Poor Sleep Qualityduration; habitual sleep efficiency; sleep disturbances; use of sleep medication; and daytime dysfunction. The CPSQI had been proven to have a very good general reliability and testretest reliability. The CPSQI includes a cutoff value of 7, with higher worldwide scores indicating poorer sleep excellent [24]. Bullying behaviors. You’ll find 4 profiles linked with bullying: pure bullies (students who bully and are never victims), pure victims (students that are victims of bullying and in no way attack other individuals), bullyvictims (students who’re each victims of bullying and who bully other individuals) and neutral (students never involved in bullying). The concerns about bullying and victimization consisted of 2 components, with the answers given on a 3point scale as follows: in no way, 2sometimes (a single or two occasions) or 3often (more than 3 times). Students reporting at least one particular bullying behavior having a frequency of “often” previously 30 days have been classified as bullies [26]. Victims had been people who reported no less than a single victimization expertise previously 30 days with a frequency of “often.” Bullyvictims met the criteria for being each a bully in addition to a victim. All other students were labeled PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/24134149 as neutral [27]. Bullying questionnaire. The queries about bul.