Ayurveda is the most ancient science of life. As such it is not concerned only to the cure of diseases but also aims to relieve the humanity from all categories of miseries- physical, mental, intellectual and spiritual. This important triune consists of Ahara (food), Nidra (Sleep) and Brahmacarya (Good conduct). These three have been considered as Upastambha or the basis of life and health. Out of the three Upastambhas, Nidra or sleep is the secondary important pillar of life. It is a physiological state of rest for the body, mind, sense and motor organs. When the mind is exhausted and ex- hausted sense organs detract from their objects, Nidra has been given more importance and considered to be the best in Ayurveda. This article is an attempt to present information that is discussed in Ayurveda text related to Nidra (sleep).

Introduction:

Ayurveda, the science of life has mentioned various principles, for well being of the humans. There are two basic aims of Ayurveda, which are mentioned in the following quote –

1.Swasthasya swastha rachanam (prevention of disease) 2.Aturasya vikara prashanam (cure of disease)1. To fulfill the aim of life (prevention of disease) of Ayurveda, the theory of Triupasthambha has great place, as Acharya Caraka says that Ahara, Nidra and Bramhacharya are the three Upastambhas of life and play a key role in the maintenance of health and long life span. Being supported by these three will regulate factors of life, the body is endowed with strength, complexion and growth, and continues up till the full life span of life, provided a person does not indulge in such regimens as are detrimental to health[2]. While discussing about Nidra, the ancient Acharyas have stated that happiness and sorrow, growth and wasting, strength and weakness, virility and impotence and the knowledge and ignorance as well as the existence of life and its cessation depend on the sleep, It is one of the life maintaining factors and if not used properly several fatal diseases may produce[3]. Nidra has been considered as Brihana factors (nourishing factors) in routine life means it promotes health by nourishing Dhatus[4] and increasing Kapha which is responsible for the strength and immunity of the body as well as mind. Increased Kapha promotes physical health and immunity are promoted by Sthirita(stability), Snigdhata(unuctousness) and Guruta(heaviness) while mental health and immunity are promoted by Kshama(forgiveness), Dhrit(steadiness) and Alobha (contentment), which are the functions of Kapha in normal state on the other hand, Nidra also promotes health by increasing Shukra Dhatu, essence of the body and the same affects as like Kapha

Etymological derivation of Nidra:

The word Nidra is feminine formed by the prefix ni+dra+rak+ta. This is a state of nature which causes encapsulation to the consciousness of a person.

Definition:

Ever since modern people are unable to define it accurately from the time it is a question in every mind that what is sleep, how it occurs and what is its role in health. But the great sages of India had the perfect knowledge regarding the sleep.  The definitions are as follows – Sleep is the mental operation having the absence of cognition for its grasp, Vyas while commenting Patanjali Yoga Darshana made a statement as “Sleep is a state of unconsciousness, but the consciousness remains about his own unconsciousness . Charak affirmed that when the mind (as well as soul) gets exhausted or becomes inactive and the sensory and motor organs become inactive then the individual gets sleep [8]. Sushruta described the sleep occurs when the Hridaya the seat of Chetana is covered by Tamas [9]. In Astanga Sangraha, Vagbhata stated that - the Manovaha Srotas become accumulated with Shleshma and mind is devoid of sense organs because of fatigue, when individual falls asleep .

Proper Sleep:

The sleep caused by nature of night is excellent sleep. It keeps every one lively, nourishes them like mother, so called as Bhutadhatri . It is like Maya of Visnu, it naturally comes to all beings. It is also known as Papini as it destroys all means, through which good action can be done at that time .

Proper way to sleep:

Over a comfortable bed in home &at proper time at which sleep is accustomed , one should go to sleep.

Relation of sleep with Health:

Happiness, misery, nourishment, emaciation , strength ,weakness, sterility, virility, knowledge, ignorance , life& death, all are dependent on proper or improper sleep[3]. Untimely sleep & excessive sleep take both happiness & longevity like Kala Ratri i.e. fierceful night. At the same time if properly enjoyed, they bring about happiness, longevity to human being as real knowledge i.e. Satya Buddhi brings about Siddhi to Yogi .

Relation of sleep with nourishment & malnourishment of body:

Awakening at the night increase dryness in the body . Day sleep increase unctuousness in the body & sleeping in sitting posture during day time does not increase unctuousness or dryness [15]. Like the proper diet, proper sleep is essential for maintenance of the body. Proper sleep increase weight, induces obesity where as less sleep produce emaciation .

Production of sleep:

When Tamas increases the person sleeps. When Satva increases person awakens. Naturally the Tamas & Satva qualities alternately are held responsible for sleep & awakening .

Effect on heart:

Heart which is like the lotus in the downward direction, blooms in wakeful state & closes while a sleep.

Types of Nidra:

Ayurveda has different opinions regarding the types of sleep. Basically Nidra can be classified into type’s viz. Svabhavika (natural) and Asvabhavika (abnormal). Out of the former Svabhavika Nidra is regular every night, which offers beneficial effects for the living beings, whereas the later Asvabhavika is one can be due to different causes of pathological in origin.

Acharya Caraka has classified Nidra in following manner according to causes -

1. Tamobhava- caused by Tama.
2. Slesmasamudbhava- caused by vitiated Kapha .
3. Manah-Sarira Srama Saambha- caused by mental and mental exertion.
4. Agantuki-indicative of bad prognosis leading imminent death.
5. Vyadhi-Anuvartini- caused as a complication of other disease like Sannipataja jwara etc.
6. Ratri-Swabhava Prabhava- caused by the very nature of the night.

Acharya Vagbhata has classified in seven types as following manner -

1. Kalaswabhawaja- it is produces at the accustomed time. i.e. nights
2. Amayaja- it is produced due to effect of diseases.
3. By fatigue of Mana- when Mana is exhausted
4. By fatigue of Sharira- when body is exhausted
5. Shleshmaprabhavaja- it is produced due to predominance of kapha
6. Agantuka- this type of Nidra is produced by external factors e.g. traumatic etc.
7. Tamobhava- it is produced by predominance of Tamoguna.

Physiology of sleep (Nidra):

When Manas is exhausted then sleep occurs this phenomenon can be understood in this manner. According to Howell, sleep is due to cerebral ischemia. Cerebral cortex is the seat of higher centres like pre and post central gyres, association area etc., which have the correlation with mental activities described in Ayurveda. So due to the reduction in cerebral blood supply Manas becomes Klanta that causes sleep . Further, during sleep, Indriyas (both Jnanendriya and Karmendriya) become inactive by the detachment from their sense organs or from their work.

Diseases produced due to improper sleep:

Improper sleep will lead to different diseases like Halimaka (type of jaundice), head ache, heaviness of the body, fever ,giddiness, mental disturbances, obstruction of channels, diminution of Agni, oedema, tastelessness, nausea, rhinitis, half sided head ache ,itching, body ache, urticaria , ulcers, cough, drowsiness, disease of throat & features of poisoning[.Execesive sleep should be treated by emesis, purification procedures, langhana, blood letting & mental stimulants.

Anidra:

By going through the previous description, it is quite evident that Nidra is not only an important but an essential phenomenon of life, which affects the body and mind equally in a favourable way when it is enjoyed in a rightful manner. Otherwise the inadequate Nidra leads to various problems like Dukha, Karshya, Abala, Klibata, Ajnana at last leads to death also . Charaka mentions the factors are Atiyoga of Vamana, Atiyoga of Virechana, Atiyoga of Nasyakarma, Atiyoga of Raktamokshana and Atiyoga of Dhoomapana. Due to the excess use of these factors makes the Vata vitiation and Anidra is inducted. Ati Vyayama, Ati Upavasa and Asukha Shayaa are the causatives of Vata vitiation, thus the Anidra is induced. Atichinta, Atikrodha and Atibhaya are the Manasikakarana leading to Tama Kshaya and Rajo Vruddi induces the Anidra. Along with these, Charak considers, some others Chikitsa procedures of Atinidra as causative factors for Anidra, which are as follows - Satvaaudarya (increased Satwa), Tamojayee (conqueror of tama),Karya (engaged in work), Kala (old age), Vikara (disease), Prakriti (personalities such as Vata) and Vayu (Vata Dosha) are the causes of Anidra. Further Sushruta has mentioned some extra Nidana factors which may cause Anidra; these factors are Vata Vridhi, Pita Vridhi, Manastapa, Kshaya and Abhighata.

Methods &measures to induce sleep:

Sleeplessness can be treated by massage, unction, bath, soup of domestic, marshy &aquatic animals, Sali rice with curds, unctuous substance, milk, alcohol &psychic pleasure, smell of scents &hearing of sounds of one’s own taste, comfortable touch ,application of anointments to body, Tarpana for eyes, comfortable bed, home &sleeping at proper time.

Indications for day sleep:

Sleeping during day time is prescribed for those who are emaciated by singing, study, alcoholic drinks, sexual act, elimination therapy, carrying heavy weight, walking long distance, suffering from phthisis, wasting, thirst, diarrhoea, colic pain, dyspnoea, hiccough, insanity, those who are too young, weak, emaciated, injured by fall, assault, exhausted by journey, vigil, anger ,grief ,fear &those accustomed to day sleep. In summer when nights are shorter, Vata gets aggravated in the body due to absorption of fluid, so day sleep is prescribed for all.

Sleep as a nonsupressible (Adharaniya Vega):

Acharya Caraka has described about non suppressible urges in Sutrasthana chapter seven. He has included Nidra in 13 non suppressible urges[28]. He has further said that various type of disease occur by the suppression of these urges. Acharya Susruta has accepted generation of 13 types of Udavarta by the suppression of these non-suppressible urges mentioned by Caraka[29].Acharya Caraka has also mentioned 6 types of Udavarta by the suppression of these urges but he did not include Nidra among those.

Nidra as a Therapy: Carakacharya has described Nidra in Astauninditiyadhyaya where eight types of undesirable constitutions from the treatment point of view are mentioned. Among them Atisthaulya And Atikrisha are especially undesirable constitutions because they are always suffer with any disease. He has said that Atisthula and Atikrisha Purusa are to be treated by Karshana and Bringhana therapies respectively. Nidra is included under Brihana factors. That is why Nidra is described here as a therapy in the management of Karshya Roga.

Facts about Nidra:

* Nidra is one of the important Upastambhas of life.
* It plays great role in prevention of the disease which are produced due to improper Nidra.
* It promotes health when it is used as prescribed regimen.
* According to rules and regimen, Nidra should be used and taken seriously.
* We must use Nidra as a therapy in some diseases.