Some men can still carry on night after night on into their 60s, while others find at a younger age that "the spirit is willing, but the flesh is unable." Most men can expect their hormone levels to stay normal up to age 50 before beginning to decline in later middle age.
但每個人的個別差異很大，有些人年過耳順仍夜夜春宵，有些人則較早出現力不從心的症狀，不過一般人在五十歲前，體內的男性荷爾蒙濃度都屬正常，一直到中年後期，才開始江河日下。