Recent epidemiological studies show that the prevalence of sleep-disordered breathing seems to be higher than previously estimated in the middle to older aged general population with approximatively 49% of men and 23% of women being affected. This higher than expected prevalence of sleep-disordered breathing seems to be due to the high sensitivity of current recording techniques and to the new and more inclusive definition of respiratory events (hypopnea definition in particular). Male sex, age, and truncal obesity (large neck girth, high waist to hip ratio) are the main risk factors for sleep-disordered breathing. Among sleep-disordered breathing patients, different phenotypes can be observed according to the underlying pathophysiologic mechanism of their condition : purely anatomical impairment, central breathing control instability (high "loop gain"), low arousal threshold, or sleep-associated pharyngeal muscles dysfunction. A better phenotyping of the patients could help directing the treatment to the specific cause of their disorder.