Method and system for monitoring stress level of a subject. Beat-to-beat time variation and stroke volume variation of the heart a subject are obtained simultaneously, and a stress level indication is determined as a function of the beat-to-beat time variation and the relative stroke volume variation. More accurate and reliable estimates for stress level may be obtained.本發明提供一種用於監控目標對象的應力位準的方法與系統。目標對象的心臟的心跳至心跳時間變異與脈搏輸出量變異會同步被取得；以及以該心跳至心跳時間變異與該相對的脈搏輸出量變異為函數決定一應力位準指示符。本發明可以取得更精確及可靠的應力位準預測值。
