As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school, which bases its tenets on the doctrines laid out in the Brahma Sutras, a work by the sage Vyasa that summarizes and systematizes the philosophical teachings of the Upanishads. You can read the Brahma Sutras here. In any case, in the beginning of Adhyaya 3 Pada 2 of the Brahma Sutras, Vyasa discusses the nature of different states of consciousness. Here is what he says about Sushupti or deep sleep:

Topic-2: The Soul in Deep Sleep

  1. The absence of that dream (ie., dreamless sleep) takes place in the nerves and the Self, as it is known to be so from the Upanishads.
  2. For the same reason, the soul’s waking up is from this supreme Self.

As I discuss in this answer, all the commentators on the Brahma Sutras interpret these Sutras as saying that during deep sleep, the Jiva resides in Brahman. Here is what Adi Shankaracharya says in his Brahma Sutra Bhashya, for instance:

'The absence of that,' i.e. the absence of dreams--which absence constitutes the essence of deep sleep-takes place 'in the nâdîs and in the Self;' i.e. in deep sleep the soul goes into both together, not optionally into either.--How is this known?--'From scripture.'--Scripture says of all those things, the nâdîs, &c., that they are the place of deep sleep; and those statements we must combine into one, as the hypothesis of option would involve partial refutation.... That again the nâdîs and the pericardium have to be combined as places of deep sleep appears from their being mentioned together in one sentence ('Through them he moves forth and rests in the purîtat). That that which is (sat) and the intelligent Self (prâgña) are only names of Brahman is well known; hence scripture mentions only three places of deep sleep, viz. the nâdîs, the pericardium, and Brahman. Among these three again Brahman alone is the lasting place of deep sleep; the nâdîs and the pericardium are mere roads leading to it. Moreover (to explain further the difference of the manner in which the soul, in deep sleep, enters into the nâdîs, the pericardium and Brahman respectively), the nâdîs and the pericardium are (in deep sleep) merely the abode of the limiting adjuncts of the soul; in them the soul's organs abide.

Nor do we finally maintain that the nâdîs, the pericardium, and Brahman are to be added to each other as being equally places of deep sleep. For by the knowledge that the nâdîs and the pericardium are places of sleep, nothing is gained, as scripture teaches neither that some special fruit is connected with that knowledge nor that it is the subordinate member of some work, &c., connected with certain results. We, on the other hand, do want to prove that that Brahman is the lasting abode of the soul in the state of deep sleep; that is a knowledge which has its own uses, viz. the ascertainment of Brahman being the Self of the soul, and the ascertainment of the soul being essentially non-connected with the worlds that appear in the waking and in the dreaming state. Hence the Self alone is the place of deep sleep.

And here is what Ramanujacharya says in his Sri Bhashya:

Next the state of deep dreamless sleep is enquired into. Scripture says, 'When a man is asleep, reposing and at perfect rest, so that he sees no dream, then he lies asleep in those nâdîs' (Kh. Up. VIII, 6, 3); 'When he is in profound sleep and is conscious of nothing, there are seventy-two thousand veins called hita which from the heart spread through the pericardium. Through them he moves forth and rests in the pericardium' (Bri. Up. II, 1, 19). 'When a man sleeps here, he becomes united with the True' (Kh. Up. VI, 8, 1). These texts declare the veins, the pericardium, and Brahman to be the place of deep sleep; and hence there is a doubt whether each of them in turns, or all of them together, are that place. There is an option between them, since they are not in mutual dependence, and since the sleeping soul cannot at the same time be in several places!--To this the Sûtra replies--the absence of dreams, i.e. deep sleep takes place in the veins, in the pericardium, and in the highest Self together; since these three are declared by Scripture. When different alternatives may be combined, on the ground of there being different effects in each case, it is improper to assume an option which implies sublation of some of the alternatives. And in the present case such combination is possible, the veins and the pericardium holding the position of a mansion, as it were, and a couch within the mansion, while Brahman is the pillow, as it were. Thus Brahman alone is the immediate resting-place of the sleeping soul.

See my answer here for quotes from other commentries saying the same thing. But my question is, what is the purpose of the Jiva residing in Brahman during deep sleep?

Note that I am not asking how we know that the Jiva resides in Brahman during deep sleep; that is thoroughly addressed in the various commentaries on the Brahma Sutras. In some sense I'm interested in the purpose of the deep sleep state. Not the scientific or health purpose of sleep, but rather, what is the benefit of the Jiva going into a state every night where it resides in Brahman? What purpose does that serve?

Are there any scriptures or works by Acharyas that address this?

  • 4
    Pandya's answer below is good. Remember according to Sankara and Advaita, there is no 'purpose' to this universe or the three states of consciousness in it which are illusory. See Gaudapada's Karika I. 7-12. Nikhilananda says in regards to Sankara's commentary on verse 7 that "Sankara compares such people [who investigate the process of creation and that within it] to those who, though knowing a phenomenon to be magic, waste their time in discussing it. The wise man is interested in Ultimate Reality and no in illusory manifestation." – Swami Vishwananda Sep 26 '16 at 14:56
  • Maya arises within Maya. One explanation (all explanations being from within Maya) of the illusion is as good as another. – Swami Vishwananda Sep 26 '16 at 14:59
  • @SwamiVishwananda By the way, can you take a look at my question about Anandagiri's commentary on Adi Shankaracharya's Brahmasutra Bhashya? hinduism.stackexchange.com/q/15489/36 – Keshav Srinivasan Oct 18 '16 at 2:05
  • Let me know which further details you're looking for so-that I can edit my answer to include it. Thanks – Pandya Dec 2 '18 at 15:36

It is explained in the Chhandogya Upanishad - Aadhyaya-6, Khanda-8.

  • What is the Sushupti actually and why do we experience it?:

    उद्दालको हारुणिः श्वेतकेतुं पुत्रमुवाच स्वप्नान्तं मे सोम्य विजानीहीति यत्रैतत्पुरुषः स्वपिति नाम सता सोम्य तदा सम्पन्नो भवति स्वमपीतो भवति तस्मादेनꣳ स्वपितीत्याचक्षते स्वꣳह्यपीतो भवति ॥ ६.८.१॥

    Uddalaka the son of Aruna said to his son Svetaketu: "Learn from me, my dear, the true nature of sleep. When a person has entered into deep sleep, as it is called, then, my dear, he becomes united with Pure Being (Sat), he has gone to his own Self. That is why they say he is in deep sleep (svapiti); it is because he has gone (apita) to his own (svam).

    I'm here quoting that part of Adi Shankaracharya Bhashya which is related to question.

    .....Question :-"How is this merging into one's oWn known to ordinary men (v/ho are not expected to have the experience"?
    They say that they infer it from the fact of Sleep being due to fatigue incurred during the waking state. What happens is that during the waking state, man becomes fatigued through experiencing exertions involved in the pleasures and pains brought about by Merit and Demerit,- the organs also, becoming tired by numerous functioning, retire from further functioning; this is what has been thus declared in Vedic texts' Speech is tired, Eye is tired' etc., etc., (Brhada. Upa. 1. v. 21.) and again, 'Speech' is held up, Eye is held up, Mind is held up', (Brhada. Upa. II. i. 17.) which shows that the organs are all swallowed up by the Life-breath ;-it is Life-breath alone which is not tired and lies awake in the nest of the body: it is in this state that the 'Living Self', for the removal of fatigue, retired into its own self in the form of the Deity; inasmuch as no removal of fatigue would be possible apart from this resting within his own,- it is only right that people should entertain the idea that & he is gone to his own'. In the ordinary world, it is seen that when people suffering from fever and other diseases are cured of them, they regain their own and rest; similar is the case here also; hence, what has been said is quite right; this has also been made clear by such texts as & just as, the Kite or the Heron having flown and becoming tired etc., etc.,' (Brhada. Upa. IV. iii. 19.).....

  • Why does Jiva rest in Supreme? Explained with example:

    स यथा शकुनिः सूत्रेण प्रबद्धो दिशं दिशं पतित्वान्यत्रायतनमलब्ध्वा बन्धनमेवोपश्रयत एवमेव खलु सोम्य तन्मनो दिशं दिशं पतित्वान्यत्रायतनमलब्ध्वा प्राणमेवोपश्रयते प्राणबन्धनꣳ हि सोम्य मन इति ॥ ६.८.२ ॥

    "Just as a bird tied by a string to the hand of the bird—catcher first flies in every direction and then finding no rest anywhere, settles down at the place where it is bound, so also the mind (i.e. the individual soul reflected in the mind), my dear, after flying in every direction and finding no rest anywhere, settles down in the Prana (i.e. Pure Being); for the mind (the individual soul) is fastened to the Prana (Pure Being).

    Quotes from Bhashya:

    The following example illustrates what has been said above. Just as, a bird, tied to a string-in the hands of the Bird-killer ,-having flown in several directions. with a view to extricate himself from the bondage, having f)ow.n in all directions,-and finding no resting place- support for rest-elsewhere-apart from the place to which it is fastened ,-settles down at the place to which it is fastened ;-in the same manner, as has been Sl:en in this example cited, the Mind,-which has been the subject- matter of our conversation, which has been found to have sixteen parts developed by food; the tern1 ' Mind' stands for the ' Living Self' entering and residing in the Mind and chracterised by it,-just as, when it is said that 'the Raised platform shouts', the terrp , Raised platform' stands for the man on the platform ;-now, this ' Living Self' along with its limiting adjunct called' Mind' ,-having flown in several directions, in the shape of pleasure and pain and other experiences during the waking state and during dreams led thither by his ignorance, desires and Karmic Residua,- i. e. having experienced all these,-and not finding an resting place ,-shelter for resting-elsewhere-apart from his. own Self called 'Being ',-settles down at the Life- breath ;-the term' PriilJa " , Life-breath', here stands for the Supreme Deity named 'Being' as characterised (circumscribed) by the aggregate of all causes and effects,-as is indicated by such Vedic texts as-' the Life-breath of life- breath, (Brhada. U pa. IV. iv. 18.) 'Having Life-breath for his body, in the fornl of Light etc' Hence, it is this' Life-breath', the Deity named' Life-breath', at which he settles down.-' Because, my dear, Mind is fastened to the Life- breath ';-' Mind' here standing for that Mind in which the said Deity is resting,-that is, the 'Living Self' characterised by the said' Mind '. --(2)

  • Why is only Supreme being (Satya/Brahman) shelter?:

    तस्य क्व मूलꣳ स्यादन्यत्रान्नादेवमेव खलु सोम्यान्नेन शुङ्गेनापो मूलमन्विच्छाद्भिः सोम्य शुङ्गेन तेजो मूलमन्विच्छ तेजसा सोम्य शुङ्गेन सन्मूलमन्विच्छ सन्मूलाः सोम्येमाः सर्वाः प्रजाः सदायतनाः सत्प्रतिष्ठाः ॥ ६.८.४॥

    "And where could its root be except in food (earth)? And in the same way, my dear, as food too is an offshoot, seek for water as its root. And as water too, my dear, is an offshoot, seek for fire as its root. And as fire too, my dear, is an offshoot, seek for Being (Sat) as its root. Yes, all these creatures, my dear, have their root in Being, they dwell in Being, they finally rest in Being.

    Quote from part of Bhashya:

    .....hence, from fire as the sprout,-the product-my dear, infer its root in Being, which is one only, without a second, and really and absolutely Real; all the Universe is a mere modification of words, a mere name,-superimposed by Nescience, upon the said Being,-in the same manner as the Serpent and other imaginary things are superimposed upon the Rope; hence, this Being is the root of the Universe. Hence, my dear, all the creatures-in the shape of animate and inanimate things-have their root-cause -in Being. It is not only that they have their root in Being ,-even now, during the time of their existence, the reside in Being-subsisting in Being itself; as for example, without subsisting in clay, the jar has no existence or continuance; hence, as Being is the root of all creatures, -like the clay of jar etc.-These creatures reside in Being: and at the end they rest in Being,-that is, they have their rest,: they become merged,-and have their end, in the same said Being.

I think above 5 verses from Chhandogya Upanishad are very helpful to understand why does Jiva reside in Brahman during sleep.

If you want to know more How Jiva reside in Brahman comparison of deep sleep and death and how weak up from sleep read Adi Shankaracharya Bhashya on 6 and 7 verse.

  • Sushupti is also discussed in 4th Prashna of Prashna Upanishad.

Note: Sanskrit verses are quoted from sanskritdocuments.org, English translation from shankaracharya.org and Adi Shankaracharya Bhashya from archive.org.


Krishna clearly states in the BG 14.8 that the results of ignorance are: 1. madness, indolence and sleep. He never says that it is rejuvenating and gives energy as is the case when one comes in contact with the mode of goodness which results in illumination as stated BG 14.11. Hence if in deep sleep, which is sheer ignorance, we cannot expect a result of feeling refreshed with renewed energy by contacting sheer ignorance in the form of sleep. Therefore it is simply logical that the Jiva contacts Brahman in the form of its Paramatma feature in the heart during its deep unconscious state. the deep unconscious state enables the ahankara, mind and intelligence to shut down thus allowing the soul to come in contact with Paramatma feature of the Absolute Brahman and thus being rejuvenated by its brief, yet powerful,contact with the Supreme Spirit. It is logical as ignorance from sleep cannot bring about happiness and rejuvenation that one feels after a deep sleep. Only sattva can do that.

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