Yoga Sutra - Samādhi Pada 1.6
Valid cognition, error, conceptualization, sleep, and memory.
These five vṛttis are] right knowledge, error, imagination, sleep, and memory.
The vṛttis, which bind puruṣa to the world of saṁsāra, are enumerated here. Patañjali lists five distinct types of vṛttis. The implication, in essence, is that the human mind finds itself in one of these five states at any given moment. According to the Yoga tradition, all possible mental states that can be experienced can be categorized as manifestations of one of these five types of vṛttis. Any other states of mind that one might conceive of would be considered by the Yoga tradition as a subset of one of these five essential categories. The commentators reserve their comments for the ensuing sūtras, which explain each of these items in turn.
pramāṇa (n.) valid cognition, correct notion, right perception; pra (before, forward) + māṇa (means of proof, demonstrating) from √mā(measure, prepare, display)
viparyaya (m.) misconception, error, misapprehension; vi (asunder,away)+ pari (around) + aya, from √i (go,flow)
vikalpa (m.) conceptualization, imagination; vi (asunder, away) + kalpa, from √kip (correspond, in accordance with, suitable to)
nidrā (f.) sleep, slumber, ni (down, into) + √drā (sleep)
smṛtayaḥ (m. nom. pl.) memory; from √smṛ (remember) [end DV epd.]