In this study, determination of obstructive sleep apnea (OSA) from polisomnography records is aimed. The signals of OSA patients were recorded. ECG and respiration channels were used and corresponding signals were taken per 30 seconds for each epoch. Using FFT and Wavelet transform in ECG signals along with investigation of respiration signals, apnea time of OSA patients was estimated. By this approach, the prediction of apnea time prior to occurrence has been accomplished.