Inclusion Criteria:  Patients referred to the sleep-school at Bjørgvin DPS psychiatric hospital Patients fulfilling the Diagnostic Manual for Mental Disorders (DSM-V) criteria for DSWPD comorbid to moderate to severe psychiatric illness (confirmed F-diagnosis based on the International Statistical Classification of Diseases and Related Health Problems (ICD-11) diagnostic system that are used in Norway in addition to DSWPD and/or scores of ≥19 on BDI and/or scores of ≥16 on BAI at the time of referral to the sleep school)  Exclusion Criteria:  Night work Patients that do not fulfil the DSM-V criteria for DSWPD comorbid to moderate to severe psychiatric illness (confirmed F-diagnosis based on the ICD-10 diagnostic system that are used in Norway in addition to insomnia and/or scores of ≥19 on BDI and/or scores of ≥16 on BAI at the time of referral to the sleep school)