[1] Univ Bergen, Dept Global Publ Hlth & Primary Care, Bergen, Norway
[2] Univ Bergen, Ctr Elderly & Nursing Home Med, Bergen, Norway
[3] Haukeland Hosp, Norwegian Competence Ctr Sleep Disorders, Bergen, Norway
[4] Univ Bergen, Fac Psychol, Bergen, Norway
[5] Univ Bergen, Dept Global Publ Hlth & Primary Care, Bergen, Norway
[6] Univ Bergen, Ctr Elderly & Nursing Home Med, Bergen, Norway