Nidra (Samskrit: निद्रा) refers to the sleep. Sleep is not merely the state of reversible unconsciousness but, according to Ayurveda, sleep is that state of body, mind, senses and energy where the interaction between purush (पुरुषः) and loka (लोकम्) is suspended for some time. This provides rest and relaxation to body, mind and senses which consequently relax, rejuvenate and re-energize the person. Thus, sleep is associated with health and well-being of body (शरीरम्), mind (मनः) and senses (इन्द्रियाणि). Sleep plays major role in the energy dynamics of the body-mind system of a human being. It is that aspect of life process which helps to restore and preserve energy which which could be then utilized to carry out body tissue repair. Because of this Ayurveda has considered sleep as one of the 3 supports of life and thus has given significant attention to the causes, process, effects and disorders related to the sleep.
Ayurveda has put forward the concept of 3 supporting pillars of life. These are called as 3 upastambhas. It is stated that, strength, immunity and growth of any individual is dependent on well-regulated support of 3 factors namely Ahara (food), nidra (sleep) and observance of bramhacharya (celibacy/control of senses). These are called supports or pillars of one’s Ayu or life.
त्रय उपस्तम्भा इति- आहारः, स्वप्नो, ब्रह्मचर्यमिति; एभिस्त्रिभिर्युक्तियुक्तैरुपस्तब्धमुपस्तम्भैः शरीरं बलवर्णोपचयोपचितमनुवर्तते यावदायुःसंस्कारात् संस्कारमहितमनुपसेवमानस्य, य इहैवोपदेक्ष्यते॥ (Char Samh 11.35)
traya upastambhā iti- āhāraḥ, svapno, brahmacaryamiti; ebhistribhiryuktiyuktairupastabdhamupastambhaiḥ śarīraṁ balavarṇopacayopacitamanuvartate yāvadāyuḥsaṁskārāt saṁskāramahitamanupasevamānasya, ya ihaivopadekṣyate॥ (Char Samh 11.35)
Meaning: Three supporting pillars of life: Ahara (food), nidra (sleep) and observance of bramhacharya ( celibacy/control of senses). By the wisdom of well regulated support of these three pillars one can get body with strength, good complexion and proper growth and this continues throughout life, provided person does not get involved in regimens which are detrimental for health, these are discussed in this chapter.
Thus, Nidra plays integral role in one’s health and wellness and therefore it is regarded as one of the 3 supports of life.
निद्रा उत्पत्तिः॥ Utpatti of Nidra
Acharya Sushruta has stated that, Nidra originates from maya of devata Vishnu (विष्णुः). Thus, nidra is said to be Vaishnavi (वैष्णवी). As per Hindu tradition, Brahma, Vishnu and Shiva are the 3 devatas (देवताः) which represent the 3 dimensions of cosmic energy, creation, sustenance and destruction respectively. In this, Vishnu devata sustains the creation and represents the eternal principle of preservation. Thus, with respect to the human body, Vaishnavi Nidra is said to be the one that sustains life and helps in energy preservation. Therefore while evaluating the energy dynamics of human body Ayurveda lays high emphasis on sleep disturbances of the individual.
Factors responsible to induce sleep
निवृत्तिः पुष्टिकराणां, पुष्टिःस्वप्नकराणाम्...| (Cha.Su 25.40)
Acharya charaka, in Charaka samhita has clearly explained the association of ones mental status with the sleep. It is noted that, relaxation and retirement from the stress leads to pushti i.e. nourishment and that in turn helps in induction of sleep. Thus it is frequently seen that those who are stressed excessively and can not stop thinking about a certain stressful thought (can not get detached), face disturbances in sleep.
निद्रा त्रिगुण संबंधः॥ Nidra and Triguna
Nidra is said to occur due to Tamas guna abundance in body while Sattva guna abundance helps one to wake-up from sleep. Therefore, abundance of these gunas in surroundings during day & night cycle naturally makes one feel sleepy or awakened.
निद्राहेतुस्तमः, सत्त्वं बोधने हेतुरुच्यते । स्वभाव एव वा हेतुर्गरीयान् परिकीर्त्यते ॥ (Sush Samh 4.35)
nidrāhetustamaḥ, sattvaṁ bodhane heturucyate । svabhāva eva vā heturgarīyān parikīrtyate ॥ (Sush Samh 4.35)
Rajas guna is responsible for movements of manas. Manas is the main component of sleep pathway and it should be detached from all the other activities to initiate the sleep process. Excess of rajas constantly involve manas in some sensory or motor activity and thus unregulated movement of manas disturbs the normal pattern of sleep.
निद्राभेदाः॥ Types of Nidra
Ayurveda literature described various types of sleep. There exist various causes related to body, mind and also the outer environment which may affect the process of sleep. The cause, effect and type of sleep decide its positive or negative effects on body and mind. Therefore, based on such factors, sleep has been categorized into various types by Acharya Charaka. These are as below
Abundance of Tamas guna leads to induction of sleep. Therefore, tamas excess could be the only causative factor for sleep in some individuals at some time and then such kind of sleep is identified as Tamobhava.
Dominance of kapha dosha in body induces sleep. Thus, when excess kapha causes sleep it is called as shleshmasamudbhava.
In some rogas, excess sleep is manifested as a symptom. In such cases the sleep is believed to be disease related.
Sleep is also observed as an Arishta lakshana (अरिष्टलक्षणः) in certain cases. Such sleep along with some other symptoms is indicative of that person's journey approaching towards end of life.
Exhaustion of mind (Manas) due to its activities like overthinking and exhaustion of body from strenuous activities makes body, mind and senses incapable of performing further activities and then the exhausted individual sleeps. Such kind of sleep resulting from exhaustion is included under this category.
Tamas guna dominance due to darkness is believed to be the natural property of night (Ratri). And due to dominance of tamas sleep is induced. This is the course of natural cycle of sleep. Thus sleep that is induced due to day and night cycle, at night, is included in this category. This type of sleep is called as Bhootadhatri (भूतधात्री) i.e. the one that sustains living beings or their life.
रात्रौ जागरणम्॥ Ratrau Jagaranam
Jagaranam (जागरणम्) means to stay awake. Thus, staying awake at night is known as Ratrau jagaranam (रात्रौ जागरणम्). The human body is designed and programmed in such a way that it works in tune with the nature. Thus the biological clock inside human body is set according to day-night cycle in external environment. When it is night, the outside environment is dark and cool. It is believed that the darkness is the attribute associated with Tamas or Tamo guna. Thus there is abundance of tamo guna in environment which naturally helps to induce the sleep in humans. An individual sleeps at night due to change in external environment and thus the sleep at night is natural and beneficial. However, if one stays awake at night it is called as Jagaranam. Staying awake late night causes adverse effects on health. It is said to cause imbalance of doshas. According to Ayurveda it increases excessive dryness and heat in body which leads to increase in inflammation in body tissues. Thus, staying awake at night is listed as cause for multiple diseases.
Diwaswap refers to sleep at daytime. According to natural cycle an individual performs various activities in a daytime or when there is sunlight in abundance. Lack of Tamas guna keeps one awake. But when one sleeps at this time it is not in accordance with the natural course of time. Sleeping at daytime increases Kapha dosha levels in body leading to multiple disorders. Thus Diwaswap is not advisable rather discouraged except in harsh summers and certain medical conditions or age groups.
निद्रावेगः॥ Nidra vega : Sleep, The natural urge
Nidra is identified as one of the vegas (वेगाः). Vega refers to the natural urge of the body which is felt or generated in order to fulfill the demand of body to correct the imbalance or to reestablish the equilibrium. Forceful induction or suppression of these urges affect health and well-being. Thus forcible induction of sleep known as Nidra udirana (निद्रा उदीरण) and forcible suppression of urge to sleep, known as Nidra vidharana (निद्रा विधारण) could lead to multiple health issues.
निद्राफलम्॥ Effects of sleep
Nidra plays important role in controlling various aspects of life in a human being. Even the sustenance of life or disruption can also be related to sleep.
निद्रायत्तं सुखं दुःखं पुष्टिः कार्श्यं बलाबलम् । वृषता क्लीबता ज्ञानमज्ञानं जीवितं न च॥
अकालेऽतिप्रसङ्गाच्च न च निद्रा निषेविता । सुखायुषी पराकुर्यात् कालरात्रिरिवापरा ॥ (Char Samh 21.11) 
nidrāyattaṁ sukhaṁ duḥkhaṁ puṣṭiḥ kārśyaṁ balābalam । vr̥ṣatā klībatā jñānamajñānaṁ jīvitaṁ na ca॥
akāle'tiprasaṅgācca na ca nidrā niṣevitā । sukhāyuṣī parākuryāt kālarātririvāparā ॥ (Char Samh 21.11)
In human beings, happiness and misery, nourishment and emaciation, strength and weakness, fertility and infertility, knowledge and ignorance, and life and death depend upon proper (and improper sleep). Happiness and longevity both can be taken away from an individual if the person takes Untimely, excessive sleep or is sleep deprived. The energy obtained from appropriately taken sleep is thus compared with the real knowledge of yogis which gives them spiritual powers.
देहवृत्तौ निद्रा॥ Role of sleep in survival
Ayurveda gives equal importance to sleep as food in maintenance and survival of human being. It is said that even life and death of a person depends on the sleep pattern of an individual. Thus, not just food but sleep is also equally important fro nourishment of a human being which makes the person capable of surviving in the external environment and perform activities required to continue his struggle for survival.
देहवृत्तौ यथाऽऽहारस्तथा स्वप्नः सुखो मतः ॥ (Char Samh 21.51)
dehavr̥ttau yathā''hārastathā svapnaḥ sukho mataḥ ॥ (Char Samh 21.51)
- Charaka Samhita (Sutrasthanam Adhyayam 11 Sutram 35)
- Charaka samhita online (Sutra Sthanasutra Chapter 11.The Three Desires of Life and important triads sutram 35)
- Sushruta Samhita (Sharirasthanam Adhyayam 4 Sutram 33)
- Charaka Samhita (Sutrasthanam Adhyaya 25 Sutram 40)
- Sushruta Samhita (Sharirasthanam Adhyayam 4 Sutram 35)
- Charaka Samhita (Sutrasthanam Adhyayam 21 Sutram 58)
- Ashtanga Hrudayam (Sutrasthanam Adhyayam 7 Sutram 55)
- Ashtang Hrudayam (Sutrasthanam Adhyayam 4 Sutram 1)
- Charaka Samhita (Sutrasthanam Adhyayam 21 Sutram 11)
- Charaka Samhita (Sutrasthanam Adhyayam 21 Sutram 51)