Obstructive sleep apnoea (OSA) is a major challenge for physicians and health care systems throughout the world. The high prevalence and the impact on daily life of OSA oblige clinicians to offer effective and acceptable treatment options. However, recent evidence has raised questions about the benefits of positive airway pressure therapy in ameliorating co-morbidities.An international expert group considered the current state of knowledge based on the most relevant publications in the previous 5â€…years, discussed the current challenges in the field, and proposed topics for future research on epidemiology, phenotyping, underlying mechanisms, prognostic implications, and optimal treatment of patients with OSA.The group concluded that a revision to the diagnostic criteria for OSA is required to include factors that reflect different clinical and pathophysiological phenotypes, and relevant co-morbidities such as non-dipping nocturnal blood pressure. Furthermore, current severity thresholds require revision to reflect factors such as disparity in apnoea-hypopnoea frequency (AHI) between polysomnography and sleep studies that do not include sleep stage measurements, in addition to the poor correlation between AHI and daytime symptoms such as sleepiness. Management decisions should be linked to the underlying phenotype and consider outcomes beyond the AHI. Copyright Â©ERS 2018.