Delayed-Action Preparations/therapeutic use; Morphine/therapeutic use; Osteoarthritis/complications; Pain/drug therapy; Sleep Wake Disorders/drug therapy; Sleep/drug effects; Administration, Oral; Adult; Aged; Analgesics, Opioid/administration & dosage; Analgesics, Opioid/therapeutic use; Capsules; Chronic Disease; Delayed-Action Preparations/administration & dosage; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Humans; Male; Middle Aged; Morphine/administration & dosage; Outcome Assessment, Health Care/methods; Outcome Assessment, Health Care/statistics & numerical data; Pain/etiology; Pain/physiopathology; Pain Measurement; Pilot Projects; Polysomnography/methods; Quality of Life; Single-Blind Method; Sleep/physiology; Sleep Wake Disorders/etiology; Sleep Wake Disorders/physiopathology; Time Factors