Aims : Obstructive sleep apnoea (OSA) is an important health problem, a multifactorial disease resulting in vatious consequences, exhibiting differences in treatment response and outcomes. This course will attempt to summarise the current knowledge regarding the: Many clinical OSA faces with variable degree of daytime sleepiness, gender differences in terms of OSA symptoms, or differences in the presence of comorbid insomnia resulted in various forms of comorbitities. The heterogeneity of OSA and its cognitive-outcomes especially affecting attention and executive functions,, and a potential bidirectional relathionship with dementia focusing on early identification, prevention and treatment startegies. The immediate pathophysiologic mechanisms influences of OSA-enhancing arrhythmogenesis and preventative strategies to mitigate OSA-induced arrhythmogenicity and related adverse outcomes. The physiological and biochemical mechanisms connecting OSA with metabolic syndrome and diabetes, to clinically-meaningful phenotyping, improved prognosis, and personalized treatment. The impact of OSA severity from mild to severe, on risk and outcome of cardiovascular diseases, also discussing excisting evidence of what is the impact of OSA with or without CPAP treatment on morbidity and mortality outcomes, highlighting also the challenges that sleep medicine faces regarding the important role of CPAP in patients outcomes and the role of compliance.