Method and apparatus for the non-invasive detection of certain breathing conditions, certain sleep disordered breathing conditions, or assessment of the person's myocardial contractility and its dynamic changes, comprising steps of: determining the sleep or wake status of a person, monitoring circulatory pulse waveforms and amplitude normalized pulse wave systolic upstrokes recorded from a person's body and determining at least one index of the upstroke to characterize the strength of the contraction of the heart during the systolic upstroke during a series of heart beats relating to a breathing cycle or an absent anticipated breathing cycle of the patient, and determining that a certain change in a breathing condition, a sleep disordered breathing condition, or assessment of the person's myocardial contractility and its dynamic changes, has occurred when a specific change in the sleep disordered breathing analysis, and the at least one index of the upstroke has been detected.
