Yōga Sūtra 1.38

स्वप्ननिद्राज्ञानालम्बनं वा।

svapnanidrājñānālambanaṁ vā।

[स्वप्न निद्रा ज्ञान आलम्बनं वा।
svapna = dream; nidrā = sleep; jñāna = knowledge / awareness; ālambanaṁ = support; vā = also;]

(Such Chitta) supports the awareness of dream and sleep state as well.

Once a Yogi reaches this state, he/she will not lose the awareness even in sleep and dream state.