感受夜氣有被動與主動兩種方式，前者為無意間被觸動，後者是有意識地創造機會。感受夜氣須具備外在條件與個人條件，外在條件指所處環境具備月、夜、清、冷、靜、寂；個人條件指身心無憂及精神處於極度專注後放鬆的狀態。宋代朱子以夜氣為涵養良心的環境，明代王陽明以夜氣為工夫，不過因為夜氣需受外在條件限制，所以後來王陽明進一步發展超越外在條件限制的夜氣工夫。超越外在條件限制的夜氣工夫與致良知一樣不受時空限制，隨時可踐行。然而最開始的夜氣工夫相對容易感知，並可作為發動良心的方法，其價值與意義不應被忽視。近來研究多將夜氣與浩然之氣等同視之，並認為夜氣具有道德性，此非孟子原意，也和朱子、王陽明的理解不同，應予以釐清。

A person’s encounter with yeqi (night-spirit; the influence of night; the pure energy of night) can be either passive or active; the former is by chance circumstance, and the latter is deliberately sought out. Most people have had both types of experience. The requisite conditions for an experience of yeqi are both external and internal; the former consists of the moon, darkness, clear weather, cool air, quiet surroundings, and solitude; the latter consists of inner tranquility and a relaxing of one’s sense of self. Confucians have understood yeqi in a variety of ways. For Zhu Xi, yeqi is an external factor which nourishes one’s conscience, and Wang Yangming made yeqi a key element of spiritual practice.