Even though the sleep apnea breathing occurs during the sleep,but it also affects the daytime's physiological status.Since sleep apnea breathing increases the risk of getting cardiovascular diseases,sleep disordered breathing has attracted significant amount attention.Conventional diagnosis processes for sleep disorder breathing is complex and time-consuming,therefore many efforts have been made in developing simplified physiological signal feature to detect sleep disorder breathing.To simplify the process of diagnosis,this study uses the ECG signals to differentiate patients and healthy subjects.In addition to traditional HRV features,this study also test a newly proposed ECG feature called degree of spectrum concentration which characterizes the degree of periodicity of the ECG waveform. Our experimental results show that sleep apnea patients have higher degree of spectrum concentration than healthy subjects.This work also tests the mutliscale entropy of this degree of spectrum concentration signal.The results demonstrate that complexity of the degree of spectrum concentration signal of the patients is higher than that of the healthy subjects.Finally,our results also detect differences between different age groups.