1. An article of manufacture comprising a memory containing computer software program instructions therein which, when executed by a processor, cause the processor to: analyze an electrocardiogram signal obtained from a human patient; partition the electrocardiogram signal into a plurality of time periods; derive an estimated respiration signal from the electrocardiogram signal; classify each time period of the plurality of time periods of the electrocardiogram signal as either apneic or normal by analyzing both the electrocardiogram signal and the estimated respiration signal; and provide a diagnostic measure of sleep apnea for the human patient based on a combined classification result obtained by combining a plurality of the classifications from the plurality of time periods.