[1] Univ Gothenburg, Sahlgrenska Acad, Ctr Sleep & Vigilance Disorders, S-41345 Gothenburg, Sweden
[2] Akademiska Univ Hosp, Pain Ctr, Uppsala, Sweden
[3] Sahlgrens Univ Hosp, Sleep Disorders Ctr, Dept Resp Dis, Gothenburg, Sweden
[4] Circadian Hlth, Nora, Sweden
[5] Sahlgrens Univ Hosp, Resp Med, S-41345 Gothenburg, Sweden