Unbound sleep monitoring is an urgent requirement. However, the existingmethods of heart rate and cardiaccycle extraction acquire limited physiological information, which lack of clinical value, or need prior knowledge about physiological information. In this study, an improved realtime heart rate and successive cardiac cycle extraction method based on ballistocardiogram(BCG) is proposed.Thismethod uses an acceleration sensor fixed on the bed side to collect the BCG signal, and the cardiac cycle sequence is obtained from the BCGsignal by the improved cardiac cycle function.The concept of cardiac cycle estimation is introduced to solve the problem that the wrong cardiac cycle occurs in the sequence. According to the cardiac cycleestimation value and by combining thecardiac candidate value and its position difference, a successive cardiac cycle is obtained from the matrix composed of the cardiac candidate value and the position.The heart rate and cardiac cycle obtained by this method are compared with electrocardiogram. Experimentalresults show that the accuracy of heart rate extraction is not lower than 9872%, and the successive cardiac cycle obtained by the two methods is within the consistency limit of 9564%.The accuracy and consistency of the proposed method are verified.