A computer-implemented method of monitoring respiration in an individual comprising obtaining a PPG signal stream from a central source site of the individual; identifying peaks and troughs of the PPG signal stream within a predetermined epoch, wherein a time between peaks or a time between troughs corresponds to a heart rate of the individual; determining (110, 112) significant local maxima of peak amplitudes and significant local minima of trough amplitudes within the predetermined epoch, wherein each significant local maxima of peak amplitude corresponds to an onset of the individual's respiratory effort to exhale and each significant local minima of trough amplitude corresponds to an onset of the individual's respiratory effort to inhale; calculating the number of significant local maxima, significant local minima, or both, during the predetermined epoch to determine the number of respiratory efforts in the predetermined epoch; and displaying the number of respiratory efforts in the predetermined epoch on a computer monitor, characterized in that determining significant local maxima of peak amplitudes comprises determining an amplitude of each peak in the PPG signal stream during the predetermined epoch; determining an increase or decrease in successive peaks in the PPG signal stream to identify initial local maxima; rejecting initial local maxima that deviate in amplitude from at least one immediately preceding and/or immediately following peak by less than a preset threshold; and designating remaining initial local maxima as significant local maxima, and wherein determining significant local minima of trough amplitudes comprises determining an amplitude of each trough in the PPG signal stream during the predetermined epoch; determining an increase or decrease in successive troughs in the PPG signal stream to identify initial local minima; rejecting initial local minima that deviate from at least one immediately preceding and/or immediately following trough by less than a preset threshold; and designating remaining initial local minima as significant local minima. obtaining a PPG signal stream from a central source site of the individual; identifying peaks and troughs of the PPG signal stream within a predetermined epoch, wherein a time between peaks or a time between troughs corresponds to a heart rate of the individual; determining (110, 112) significant local maxima of peak amplitudes and significant local minima of trough amplitudes within the predetermined epoch, wherein each significant local maxima of peak amplitude corresponds to an onset of the individual's respiratory effort to exhale and each significant local minima of trough amplitude corresponds to an onset of the individual's respiratory effort to inhale; calculating the number of significant local maxima, significant local minima, or both, during the predetermined epoch to determine the number of respiratory efforts in the predetermined epoch; and displaying the number of respiratory efforts in the predetermined epoch on a computer monitor, characterized in that determining significant local maxima of peak amplitudes comprises determining an amplitude of each peak in the PPG signal stream during the predetermined epoch; determining an increase or decrease in successive peaks in the PPG signal stream to identify initial local maxima; rejecting initial local maxima that deviate in amplitude from at least one immediately preceding and/or immediately following peak by less than a preset threshold; and designating remaining initial local maxima as significant local maxima, and wherein determining significant local minima of trough amplitudes comprises determining an amplitude of each trough in the PPG signal stream during the predetermined epoch; determining an increase or decrease in successive troughs in the PPG signal stream to identify initial local minima; rejecting initial local minima that deviate from at least one immediately preceding and/or immediately following trough by less than a preset threshold; and designating remaining initial local minima as significant local minima. determining an amplitude of each peak in the PPG signal stream during the predetermined epoch; determining an increase or decrease in successive peaks in the PPG signal stream to identify initial local maxima; rejecting initial local maxima that deviate in amplitude from at least one immediately preceding and/or immediately following peak by less than a preset threshold; and designating remaining initial local maxima as significant local maxima, and wherein determining significant local minima of trough amplitudes comprises determining an amplitude of each trough in the PPG signal stream during the predetermined epoch; determining an increase or decrease in successive troughs in the PPG signal stream to identify initial local minima; rejecting initial local minima that deviate from at least one immediately preceding and/or immediately following trough by less than a preset threshold; and designating remaining initial local minima as significant local minima.