I'm pretty sure yinrih get tired just like humans do, after mental stress or physical exertion. They may or may not go into torpor after such events. I've already established (via Doug from the Multiverse inn) that semi-spontaneous torpor is a possible reaction to strong emotion or overstimulation, either positive or negative.

Yinrih 'naps' are more lying down in a quiet place, still fully aware. They may even close their eyes, which is not typical during torpor.

During torpor, yinrih can follow simple instructions, and may even perform routine tasks like going to the bathroom to relieve themselves, operating simple mechanisms like light switches or thermostats, and so on. One can technically hold a conversation with a torpid yinrih, though their responses are slow and usually mumbled. They will remember such conversations after returning to alertness.

Torpid yinrih are less guarded in speech, not unlike some behaviors exhibited during drunkenness. In torpore varitas. To lock oneself away during torpor is seen by some as suspicious, as the torpid yinrih may wish to keep information concealed that could otherwise be elicited in this less careful state.