pramāṇa – right perception, correct understanding; viparyaya – misconception, false understanding; vikalpa – imagination, conceptualization (based on verbal delusion); nidrā – deep sleep; smṛtayaḥ – recollection, remembrance, memory;
The five mental states are (1) correct understanding of what is, (2) false understanding of what is, (3) conceptualization, (4) deep sleep and (5) memory.
Looking at the English synonyms for the Sanskrit: pramāṇa means right perception or correct understanding; viparyaya is misconception or false understanding; vikalpa means conceptualization based on a verbal delusion, and we will explain that a little later when we deal specifically with that condition; nidrā is deep sleep and smṛtayaḥ means to recollect or remember something, referring to memory.
Patañjali now lists the five distinct categories or types of vrttis, or mental states. Why are there only five you may ask? Are there other types of mental states that one can be immersed in? These ancient sages put a great deal of time and effort into understanding these things, and in this particular system of yoga, as well as in sāṇkhya yoga, these five states are considered to be distinct states or conditions of consciousness or citta. If there are any other states to consider or to focus on, they would be regarded as being somehow contained within one of these five. All other types of consciousness are considered like subsets of these five principal vṛttis, or states of consciousness.
We won’t go any further into things on this particular śloka, as the commentators themselves have traditionally not gone any further here, since now Patañjali will speak about each one of these five states in turn, and explain the nature of that state or vṛtti.