Yoga Sutra 1.38 meditating on the knowledge of dream and sleep
Sūtra I.38
Or meditating on the knowledge of dream and sleep
Either on the knowledge of dream or on the knowledge of sleep; the yogin’s mind in that form attains steadiness.
Meditating, either on the knowledge of dream or on the knowledge of sleep, the mind becomes of that form alone. What the mind meditates on as its own being, that form indeed it becomes. In the dream state, there is knowledge without any physical objects like sound and so on, and the nature of that knowledge is pure illumination. Now he meditates on what that knowledge is, but not on the remembered objects themselves (which appear in the dream). For the mind can be caught by the bridle of an object even merely remembered. But the meditation on the knowledge of deep sleep, which is essentially non-perception of any particular objects, rests on the idea of non-existence, and is peaceful, infinite, and characterized by an experience of immutability. When the mind rests on that, it is natural that it attains steadiness.