Winfried Randerath, MD, FCCP, Centre of Sleep Medicine and Respiratory Care, Solingen, Germany, speaks on the relevance of excessive daytime sleepiness (EDS) as a disease marker in obstructive sleep apnea (OSA). Prof. Randerath explains that while EDS is often a diagnostic factor in OSA, it is reported in about 50% of patients so it is important to monitor other symptoms. EDS monitoring is essential as it is associated with poorer patient prognosis in OSA comorbidities and treatment-resistant EDS can be a sign of underlying conditions or poor therapeutic response. This interview was recorded at the World Sleep Congress 2022 in Rome, Italy.