Respiratory disorders in sleep are highly prevalent and increasingly recognized. Among these, obstructive sleep apnea, resulting in daytime fatigue and somnolence, increased risk of workplace and traffic accidents but also psychosocial dysfunction, is most often diagnosed. As an independent risk factor for cardiovascular and metabolic disease, obstructive sleep apnea has recently attracted even more attention. Apart from continuous positive airway pressure, only a few alternative treatment options are available. Individual history is still most important for selecting patients for sleep studies. Fatigue and a high subjective propensity to fall asleep during the daytime, a history of snoring and breathing pauses during sleep combined with anthropometric risk factors make a diagnosis very likely. Other night-time respiratory disorders include central sleep apnea, Cheyne-Stokes respiration, obesity hypoventilation syndrome and mixed sleep apnea syndromes. The diagnosis of sleep-disordered breathing can be made by comprehensive sleep studies in a sleep laboratory, but also using portable equipment for cardiorespiratory monitoring and measurement of oxygen desaturation at home, according to pretest probabilities, individual experience and local preferences.