Excessive Daytime Sleepiness (EDS) in Parkinson’s disease (PD) is an important issue that warrants serious attention because it can have adverse effects on the quality of life of both the patient and their carers. While many patients will respond to measures designed to treat 24 hour control of PD and improve nocturnal sleep, some may require pharmacological treatment. Dr Doug MacMahon looks at the causes of EDS, its diagnosis and management.