Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 20

Sanskrit:

सत्त्वाज्जागरणं विद्याद् रजसा स्वप्नमादिशेत् ।प्रस्वापं तमसा जन्तोस्तुरीयं त्रिषु सन्ततम् ॥ २० ॥

ITRANS:

sattvāj jāgaraṇaṁ vidyādrajasā svapnam ādiśetprasvāpaṁ tamasā jantosturīyaṁ triṣu santatam

Translation:

It should be understood that alert wakefulness comes from the mode of goodness, sleep with dreaming from the mode of passion, and deep, dreamless sleep from the mode of ignorance. The fourth state of consciousness pervades these three and is transcendental.

Purport:

Our original Kṛṣṇa consciousness exists eternally within the soul, and it is also present in all the three phases of awareness, namely normal wakefulness, dreaming and dreamless sleep. Being covered by the modes of nature, this spiritual consciousness may not be manifest, but it continues to exist eternally as the real nature of the living entity.