Sleep Quality in Patients With Advanced Cancer

Inclusion Criteria: * A verified diagnosis of a malignant disease * Presence of metastatic/disseminated disease * Regularly scheduled oral, subcutaneous, transdermal or intravenous opioid treatment corresponding to step III at the WHO pain ladder with a duration of treatment not less than 3 days * Able to comply with all study procedures * Signed informed consent according to ICH Good Clinical Practice and national/local regulations Exclusion Criteria: * Not consenting to participation * Not mastering the language used at the study centre * Severe cognitive impairment as judged by the principal investigator * Any reason why, in the opinion of the investigator, the patient should not participate * Impaired use of the dominant arm * Local anatomical illness or abnormalities precluding the use of polysomnography (e.g. facial tumour) * having received chemotherapy for more than 4 weeks, having received the previous dose less than 5 days ago and receiving the next dose within the study period.