1. An improved pulse oximetry based method for recognition of a physical condition, comprising: attaching a sensor of a pulse oximeter to a body part of a patient; collecting, by a processor from the sensor, real time data representative of a timed waveform comprising repetitive photoplethysmographic pulse waves, wherein the photoplethysmographic pulse waves are responsive to changes in pulse volume of blood in the body part induced by cardiac contractions, each photoplethysmographic pulse wave defining a plurality of pulse wave components, said pulse wave components comprising a rise, a rise amplitude, a rise slope, a peak, a fall, a fall amplitude, a fall slope, a nadir, and an area, said processor detecting variations of at least one of said pulse wave components; recognizing, by the processor, an occurrence of a cluster pattern comprised of two or more closely spaced variations of said at least one of said pulse wave components induced by at least one of an apnea cluster or a hypopnea cluster; and automatically modifying or inducing modification of a treatment of the patient.