Insomnia disorder is characterised by persistent problems with sleep initiation and maintenance, significantly impairing quality of life.Persistent insomnia affects approximately 10% of the adult population and is a risk factor for several mental and physical health problems, particularly depression and cardiometabolic disease.Insomnia is also an expensive condition, associated with substantial direct and indirect costs; chiefly reflecting increased healthcare utilisation, work-related absenteeism, reduced work productivity and elevated accident risk.