WAKING, DREAM, SLEEP AND SAT-CHIT-ANANDA!
Dream is that state which when occurring “appears” to be as real as the waking state. We only “call” it dream from the “prejudice” of the waking state.
What if, extending the logic, the waking state is also a form of dream? Sages and Seers have always pointed out that our waking state is also “like a dream” (svapana-vat). Both waking and dream states are considered “dream states” since in both one perceives Reality falsely. As Gauḍapādācārya, the param guru of Adi Śaṅkarāchārya, states in GK 2.5: “The wise ones (मनीषिणः) say that the states of waking and dream are identical (स्वप्नजागरितस्थाने ह्येकमाहुर्मनीषिणः).” The Śruti says, “All the three states—waking, dream, and deep sleep—are only dreams.” (three states of dream: trayaḥ svapnāḥ त्रयः स्वप्नाः) [Aitrareya Upaniṣad 1.3.12].
This is further complicated by our experience of the deep sleep when “both dreams” of the waking and dream states disappear, along with their common adjuncts of ego, time, space, and causality.
Says Gauḍapādācārya: “Those that have settled view (निश्चिताः) see neither sleep nor dream in Turiya:” न निद्रां नैव च स्वप्नं तुर्ये पश्यन्ति निश्चिताः ॥ GK 1.14॥
There is one thing, however, which continues unchanged among these three states: the Witnessing Consciousness. The Witnessing Consciousness serves as the underlying, unchanging Reality in which the states of waking, dream, and deep sleep appear and disappear. It is like the white movie screen on which the show of light and sound is depicted.
This Witnessing Consciousness is our true nature, our real Self (Ātman). And this Pure Consciousness alone is the absolute Witnessing entity in all, says Śvetāśvatara Upaniṣad:
एको देवः सर्वभूतेषु गूढः सर्वव्यापी सर्वभूतान्तरात्मा.
कर्माध्यक्षः सर्वभूताधिवासःसाक्षी चेता केवलो निर्गुणश्च ॥ 6.11॥
eko devaḥ sarvabhūteṣu gūḍhaḥ sarvavyāpī sarvabhūtāntarātmā.
karmādhyakṣaḥ sarvabhūtādhivāsaḥ sākṣī cetā kevalo nirguṇaśca || 11||
The same Shining One (deva) is hidden in all beings, the all-pervasive One, the inner Ātman of all beings, the supervisor of all actions, the Indweller in all beings, the Witness, Conscious-entity, the Absolute and devoid of any qualities.
States come and go, but this Witnessing Consciousness is “existent” before, during and after the states.
Hence, it is “pure” Existence-Consciousness, “pure” in the sense of being bereft of any objects. This is the “Sat-Chit” part of Reality. We exist (sat) and we are aware that we exist (chit): Sat eva Chit, Chit eva Sat: सत् एव चिद् चिद् एव सत् |
It is everyone’s daily common experience that during the deep sleep, we experience “pure” bliss—“pure” in the sense that this bliss is not dependent on any object, person, or situation since the deep sleep state is devoid of all three. This is the bliss, “ananda,” aspect of Reality.
Hence, Witnessing Consciousness, the Absolute Reality, is of the nature of pure Existence-Consciousness-Bliss Absolute: SAT-CHIT-ANANDA.
The Absolute Reality is referred to as Brahman in Vedānta which is identical with Ātman, the Witnessing Consciousness, our inmost Self.
We have come full circle!
We conclude with an important verse from Māṇḍūkya Kārīkā:
अनादिमायया सुप्तो यदा जीवः प्रबुध्यते ।
अजमनिद्रमस्वप्नमद्वैतं बुध्यते तदा ॥ GK 1.16॥
anādimāyayā supto yadā jīvaḥ prabudhyate |
ajamanidramasvapnamadvaitaṁ budhyate tadā || GK 1.16||
When the individual Self, sleeping under the influence of beginningless Māyā, is awakened, then he realizes the birthless, sleepless, dreamless non-dual Turīya. [trans. by Gambhirananda, p. 212]
 See: Swami Satchidanandendra Saraswati, Sankara’s Sutra Bhasya (Self-Explained) (Banglore: Adhyatma Prakashan Karayalay, 1974), 52. Swami Gambhirananda, trans., Śvetāśvatara Upaniṣad: With the Commentary of Śaṅkarācarya (Calcutta: Advaita Ashrama, 1986), 190. [Slightly modified].
 Yā mā sā māyā या मा सा माया: That which is not, is Māyā.