成唯識論述記 7.352

7.352

述曰：此有二解：一、由；二、似。雖此眠時，無彼心所眠體，而由彼加行眠引，或沈重不自在，似有彼眠心所時，以二義故，假說無心身之分位，名眠，實非眠也。

The Commentary states: There are two explanations here: first, [it is so called] 'because of it'; second, [it is so called because it] 'resembles it'. Although at the time of this sleep the real entity of the mental factor of sleep is absent, it is induced by the preparatory sleep, or because the heaviness and lack of mastery resemble the time when that mental factor of sleep is present; by virtue of these two senses, the bodily state of being without consciousness is metaphorically called 'sleep', though in reality it is not sleep.