Most information about the structures within the brain stem that modulate respiration and sleep are gathered from animal experiments. Therefore we examined 10 patients several weeks after an infarction of the brain stem by means of polysomnography and tested the chemosensitive drives of respiration. None of these patients complained about symptoms of sleep disordered breathing. In each case polysomnographic measurements and ventilatory response curves revealed pathologic findings. The respiratory response to CO2 was diminished or completely abolished in each patient. In some cases hypoventilation or disturbances of the respiratory rhythmicity could be seen. In several cases missing REM sleep, sleep fragmentation or the reduction of slow wave sleep were observed. The study indicates that on the base of results from animal research the comparison of morphological and pathophysiological data is helpful to gain a better understanding on the coupling of the respiratory system with sleep at the brain stem level as well as on the pathomechanism of sleep related breathing disorder.