Figure 1: Overview of the study set-up. The following abbreviations are used: C: Children, A: Adults, S: Study group, Co: Control group, T1: Baseline, T2: After retention period. For example in this prospective study, the children (C) in the study group (S) at baseline (T1) are described as ‘CST1’. Other groups are named similarly with corresponding abbreviations. The study group completed the questionnaires at baseline (T1): CST1 group and AST1 group, and three months after start retention (T2): CST2 group and AST2 group. The control groups, CCo and ACo group completed the questionnaires at baseline (T1). The groups filled in the Pediatric Sleep Questionnaire (PSQ) or the adult questionnaire (Qa) as indicated in the different groups. Arrows indicate comparisons made between groups.