[1] Univ Bergen, Dept Clin Psychol, N-5020 Bergen, Norway
[2] Univ Bergen, Dept Clin Sci, Bergen, Norway
[3] Univ Bergen, Dept Global Publ Hlth & Primary Care, Bergen, Norway
[4] Haukeland Hosp, Norwegian Competence Ctr Sleep Disorders, Bergen, Norway
[5] Natl Inst Publ Hlth, Dept Hlth Registry Res & Dev, Bergen, Norway
[6] Univ Bergen, Dept Psychosocial Sci, Bergen, Norway
[7] North West Univ, Optentia Res Unit, Vaal Triangle Campus, Vanderbijipark, South Africa