PROBLEM TO BE SOLVED: To provide a sleep stage determination device, a sleep stage determination method, a sleep stage determination program, and a stress degree determination method.SOLUTION: A sleep stage determination device is provided with a detection part that uses a microwave Doppler radar to detect a body motion, respiration, a pulse wave, an HRV calculation part that calculates a cardiac rate fluctuation index HRV, a standard deviation calculation part that calculates a standard deviation of a respiration interval； a body motion intensity calculation part that calculates body motion intensity； and a determination part that uses the cardiac rate fluctuation index HRV, the standard deviation, and the body motion intensity to determine a sleep stage.SELECTED DRAWING: Figure 1【課題】睡眠段階判定装置、睡眠段階判定方法、及び睡眠段階判定プログラム、並びにストレス度判定方法を提供する。【解決手段】睡眠段階判定装置は、マイクロ波ドップラーレーダーを用いて、体動、呼吸、脈波を検出する検出部と、心拍数変動指標ＨＲＶを算出するＨＲＶ算出部と、呼吸間隔の標準偏差を算出する標準偏差算出部と、体動強度を算出する体動強度算出部と、前記心拍数変動指標ＨＲＶ、前記標準偏差、及び前記体動強度を用いて睡眠段階を判定する判定部とを備える。【選択図】図１
