Disclosed is an apparatus, system, and method of diagnosis for detecting the presence of Cheyne-Stokes breathing in a person. The apparatus, system and method of diagnosis comprise the following: means for receiving data indicative of the person's respiratory flow or ventilation, computer processing means for calculating a frequency spectrum of said data, computer processing means for analysing said frequency spectrum to determine a first measure indicating presence of a peak in said frequency spectrum, computer processing means for analysing said data to detect the presence of an apnea or hypopnea, computer processing means for analysing said data to determine a second measure indicative of a rate of increase in the person's respiratory flow or ventilation following an apnea or hypopnea, and means for providing an output signal indicating that Cheyne-Stokes breathing has been detected when both said first measure is indicative of the presence of a peak and said second measure is indicative that the rate of increase of the respiratory flow or ventilation of the person is slow.
