Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 27
जाग्रत् स्वप्न: सुषुप्तं च गुणतो बुद्धिवृत्तय: ।तासां विलक्षणो जीव: साक्षित्वेन विनिश्चित: ॥ २७ ॥
jāgrat svapnaḥ suṣuptaṁ caguṇato buddhi-vṛttayaḥtāsāṁ vilakṣaṇo jīvaḥsākṣitvena viniścitaḥ
Waking, sleeping and deep sleep are the three functions of the intelligence and are caused by the modes of material nature. The living entity within the body is ascertained to possess characteristics different from these three states and thus remains as a witness to them.
The spirit soul actually has nothing to do with the material world, having no permanent or natural relationship with it. Real renunciation means to give up the illusory identification with matter in its subtle and gross forms. Suṣuptam, or deep sleep, indicates sleeping without any dreams or conscious activity. These three states are described by Lord Kṛṣṇa as follows: “One should know that wakefulness is born of the mode of goodness, dreams from the mode of passion, and deep dreamless sleep from the mode of ignorance. The fourth element, pure consciousness, is different from these three and pervades them.” (Bhāg. 11.25.20) Real freedom means sākṣitvena, or to exist as a witness to the functions of illusion. Such an advantageous position is achieved by development of Kṛṣṇa consciousness.