[The five types are:] valid knowledge, error, imagination, sleep, and memory.

The five types of mental fluctuations:

1. Pramāṇa — Valid knowledge (direct perception, inference, reliable testimony)
2. Viparyaya — Erroneous knowledge, distorted perception
3. Vikalpa — Imagination, mental construction without basis in reality
4. Nidrā — Deep sleep
5. Smṛti — Memory, recollection of past experiences

Even valid knowledge is a vṛtti — a modification of the mind. Yoga seeks to go beyond all of them toward the pure consciousness that underlies all mental activity.