A Karma-prakṛti (type of Karma), which sometimes comes into rise, sometimes goes into subsided state or sometimes in event of availability of causes may come to rise again, e.g., Nidrā, Nidrā-nidrā etc. (Karma responsible for comfortable sleep, distressful sleep etc.).
vyavacchinnodayā api satyo yāḥ prakṛtayo hetusampattyā bhūyo'pyudayamāyānti tā adhruvodayā.
(Kapra p.29)