‘ओमित्येतदक्षरमिदं सर्वं तस्योपव्याख्यानम्’—“Om, this syllable is all this; a clear exposition of it follows”—is the immortal opening declaration of the Mandukya Upanishad. It proclaims that everything visible, everything moving through the cycles of past, present, and future, and even that which transcends these three divisions of time, is contained within Omkara. It is therefore no exaggeration, in the philosophical sense, to say that Omkara is life itself.

Omkara is not merely a sound or syllable. It is presented as the primordial resonance of the universe and of our biological existence. Viewed through the lens of modern biology, life may be understood as an uninterrupted flow of energy, information, regulation, and exchange. A living cell and a dead cell may contain many of the same physical constituents, but what has ceased in the dead cell is the organised activity through which those constituents sustain metabolism, communication, repair, and continuity.

Every cellular pulsation, the dynamic conformation of DNA, and the electrochemical signals moving through the nervous system depend upon highly ordered molecular interactions. These processes need not be identified literally with a single cosmic frequency; yet they offer a powerful contemporary metaphor for what the ancient seers experienced as Om—the underlying unity and rhythmic continuity of existence.

The genetic instructions that continuously participate in the renewal of life operate through precisely organised molecular processes. In this interpretive sense, Omkara may be seen as a symbol of the biological intelligence through which life maintains continuity and homeostasis. Under the contemplative light of the Upanishad, the elegance of Sanskrit and the intricate processes of cellular biology may therefore be brought into a meaningful dialogue—without confusing philosophical symbolism with scientific demonstration.

Every verse of the Mandukya Upanishad offers a way of understanding the changing conditions of human experience through the successive quarters of Omkara. The first stage of this journey is the waking state, which the Upanishad calls Vaishvanara:

‘जागरितस्थानो वैश्वानरोऽकारः प्रथमा मात्रा’
“The waking state, functioning through outward consciousness, is Vaishvanara, represented by ‘A’, the first measure of Om.”
(Mandukya Upanishad, 9)

This state is symbolised by ‘A’—Akara, the first sound of Omkara. Reflecting upon it, the invocation to the Agama Prakarana describes the outward movement of consciousness:

‘प्रज्ञानांशुप्रतानैः स्थिरचरनिकरव्यापिभिर्व्याप्य लोकान्
भुक्त्वा भोगान् स्थविष्ठान्।’

“He pervades the worlds through the spreading rays of consciousness that encompass all moving and unmoving beings, and experiences the gross objects of enjoyment.”

When we open our eyes each morning, awareness expands outward through the senses, taking in the animate and inanimate world. Biologically, this corresponds to an active condition of the nervous system in which sensory receptors, attentional networks, and multiple neurochemical systems participate in receiving and interpreting external stimuli.

The sound ‘A’ symbolises beginning, manifestation, and outwardly directed consciousness. The world we ordinarily regard as wholly external and separate from ourselves is encountered only through the sensory and cognitive structures by which waking consciousness organises experience. It is in this state that the embodied person most clearly experiences physical location, sequence, causality, and linear time.

As daylight fades and we move toward sleep, the Upanishad guides us into the second quarter of Omkara—the dreaming state:

‘स्वप्नस्थानोऽन्तःप्रज्ञः… तैजसो द्वितीयः पादः’
“The dreaming state, whose awareness is inward, is Taijasa, the second quarter.”
(Mandukya Upanishad, 4)

This state is represented by ‘U’—Ukara:

‘स्वप्नस्थानस्तैजस उकारो द्वितीया मात्रा।’
“Taijasa, whose field is dream, is ‘U’, the second measure of Om.”
(Mandukya Upanishad, 10)

The invocation expands this idea beautifully:

‘पश्चाच्चान्यान् स्वमतिविभवान् ज्योतिषा स्वेन सूक्ष्मान्।’

“Thereafter, through his own inner light, he experiences subtle objects arising from the powers of his own mind.”

Here, a profound philosophical and biological mystery presents itself. In the waking condition, our senses organise experience around an external world, physical location, and sequential time. In the dream state, this stable structure is radically altered. Even in the absence of sunlight, visible objects, and ordinary sensory engagement, the dreamer creates an experiential world through memory, imagination, emotion, and internally generated imagery.

The dreamer experiences a world illuminated by ‘his own light’—‘ज्योतिषा स्वेन’.

In neurobiological terms, vivid dreaming is frequently associated with REM sleep, during which several regions of the brain involved in imagery, memory, and emotion remain active, although sensory engagement with the external environment is greatly reduced. Dream experience can compress, rearrange, or distort ordinary temporal sequence. A brief period of sleep may contain the subjective impression of a much longer narrative.

This does not prove that physical space and time are created by individual consciousness. It does, however, demonstrate that our lived experience of space and time is profoundly shaped by the state and activity of consciousness. The term Antahprajna—inwardly conscious—suggests that when awareness turns inward, the form of the experienced world changes with it.

The traditional idea of the Trikaldarshi, the seer of past, present, and future, should therefore be understood primarily as a philosophical and contemplative ideal, rather than as a neurobiological consequence of dreaming. It represents a consciousness no longer imprisoned by ordinary habits of memory, anticipation, and linear sequence.

The Upanishad then guides us toward the third sound of Omkara, where differentiated experience subsides into potentiality. This is Sushupti, deep sleep, and its corresponding principle, Prajna:

‘सुषुप्तस्थानः प्राज्ञो मकारस्तृतीया मात्रा।’
“Prajna, whose field is deep sleep, is ‘M’, the third measure of Om.”
(Mandukya Upanishad, 11)

The invocation observes:

‘पीत्वा सर्वान् विशेषान् स्वपिति मधुरभुङ् मायया भोजयन्नः।’

“Having absorbed all distinctions, he sleeps, tasting sweetness, and through Maya enables us to experience it.”

In this state, neither specific desire nor differentiated imagery remains. Just as ‘A’ and ‘U’ resolve into the closing resonance of ‘M’—Makara, the diversity of experience subsides into an undifferentiated condition.

Biologically, deep sleep is associated mainly with Non-REM slow-wave sleep, during which brain activity becomes more synchronised and several restorative processes occur. These include aspects of metabolic regulation, immune function, memory consolidation, tissue repair, and physiological recovery.

The Upanishadic image of all distinctions dissolving into ‘M’ offers a contemplative counterpart to the biological restoration of deep sleep. It does not imply that deep sleep is literally the experience of Brahman, but it recognises the remarkable condition in which the ordinary divisions of waking and dream experience temporarily disappear.

This deep rest and physiological tranquillity help restore the body and nervous system, preparing the organism to awaken renewed.

Beyond philosophical exposition, the chanting of Omkara also has a practical and phonetic dimension. The slow, attentive articulation of A, U, and M brings breath, sound, bodily vibration, and awareness into a single rhythm.

The open sound ‘A’ may be felt in the lower and central regions of the body. The transition through ‘U’ produces resonance across the chest and throat. Finally, when the lips close for ‘M’, the nasal humming creates a distinct vibration within the face and head.

Slow breathing, prolonged exhalation, vocal resonance, and focused attention may help reduce physiological arousal and support parasympathetic regulation. Humming can also increase nitric oxide levels within the nasal passages, which may have local respiratory and vascular effects. However, stronger claims—such as direct stimulation of the pineal gland, large increases in systemic nitric oxide, or an immediate transition into delta sleep—require more rigorous evidence.

The transformative potential of Om chanting lies not in one isolated vibration, but in the integrated discipline of breath, sound, attention, bodily resonance, and the silence that follows.

The Upanishad ultimately points beyond all three sounds toward the fourth aspect of Omkara: Amatra, the measureless silence beyond A, U, and M, identified with Turiya:

‘अमात्रश्चतुर्थोऽव्यवहार्यः प्रपञ्चोपशमः शिवोऽद्वैतः।’
“The measureless is the fourth—beyond ordinary transaction, the cessation of phenomenal multiplicity, peaceful, auspicious, and non-dual.”
(Mandukya Upanishad, 12)

The invocation illuminates this state:

‘मायासंख्यातुरीयं परममृतमजं ब्रह्म यत्तन्नतोऽस्मि।’

“I bow to that supreme, immortal, unborn Brahman—the Fourth, beyond the enumeration produced by Maya.”

And again:

‘हित्वा सर्वान् विशेषान् विगुणगुणः पात्वसौ नस्तुरीयः।’

“May that Fourth protect us, which, having transcended all distinctions, is beyond conditioned attributes.”

Here the opening declaration—

‘यच्चान्यत्त्रिकालातीतं तदप्योङ्कार एव’
“And whatever transcends the three divisions of time is also truly Om”—

reaches its culminating meaning.

Turiya is not merely a fourth psychological state that follows waking, dreaming, and deep sleep. It signifies the unchanging ground or witnessing awareness through which all three states are known, yet which cannot itself be reduced to any one of them.

In this invocation, Shankara bows not to a remote object among other objects, but to the unborn, undivided, and imperishable ground of existence. When he says—

‘परममृतमजं ब्रह्म यत्तन्नतोऽस्मि’

—biological continuity may provide a suggestive metaphor. Individual organisms and cells are born and die, while the stream of life continues through reproduction, heredity, ecological interdependence, and the transmission of genetic information across generations.

But biological continuity is not identical with the Upanishadic Brahman, nor does it scientifically prove immortality. It may nevertheless serve as a powerful image of continuity amid change: individual forms arise and disappear, while life as an unfolding process continues.

Just as silence remains present before, within, and after sound, Amatra symbolises that which permits the sounds A, U, and M to appear but is not exhausted by any one of them.

As life advances toward maturity, the internal biological clock also changes. Hormonal rhythms, sensory capacities, sleep architecture, and neural processes gradually undergo transformation. These changes should not be romanticised or treated automatically as spiritual liberation; ageing can involve both wisdom and vulnerability, tranquillity and illness.

Yet maturity may also create conditions for reflection. As some external demands and attractions lose their intensity, a person may become less absorbed in competition, possession, and agitation. What biology describes as ageing may, when accompanied by awareness, become philosophically meaningful as detachment, inwardness, and a gentler relation to life.

The silent, measureless, and Turiya aspect of Omkara can then be approached not as a remote mystical object, but as a symbol of the still awareness beneath changing experiences.

The final directive of the Upanishad is that we should not mistake ourselves entirely for the passing states of waking, dreaming, and deep sleep. We are invited to recognise the silent ground through which these states arise and disappear.

That ground is described as Amatra—measureless; Avyavaharya—beyond ordinary transaction; Prapanchopashama—the quieting of phenomenal multiplicity; Shiva—peaceful and auspicious; and Advaita—non-dual.

It is the silence beneath the changing sounds of life, the stillness within the movement of consciousness, and, in the language of the Upanishad, our deepest and most authentic nature.