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A Critical Review of Kāla (Time) in Āyurveda

Dr. Jasmine Sehgal, Dr. Bhavna Singh, Dr. Harsh Sehgal


Kāla (time) is an abstract entity, one of the nine Kāraṇa Dravyas (causative elements in the fabric of creation), quantified for the practical purposes of executing all the activities. This review aims to explore its ancient understanding and its resonance with the contemporary notion of time by renowned theoretical physicists and the importance of Kāla, in Āyurveda. The ancient sūtras, being cryptic in nature, defined Kāla as Eka (continuum), Sarvavyāpaka (pervasive or ubiquitous), Nitya (eternal), Svayambhu (without any cause). Kāla finds diverse applications as Ayanas (half of sidereal year) and bodily changes, Ṛtu Cakra (seasonal rhythms), Roga Nidāna (a factor in aetiology), Shaṭkriyā Kāla (pathogenesis), Avasthika Kāla (state of the disease), Auṣadha Kāla (time of medicine administration), Kāla Virudha Ahāra (dietary incompatibility), Auṣadha Saṃgrahaṇa Kāla (collection of herbs) etc. Moreover, nature (exogenous rhythms) and human body (endogenous rhythms) also pertain to Kāla (time). Time is the basis of entire transformation.


Cause and effect are mediated across time. Every activity of mankind happens with reference to Kāla. The fundamental principle of Kāla, apropos the present idea of time, gives an insight into the profundity of Āyurvedicic literature. The Ācāryas of Āyurveda, namely, Caraka and Sussruta gave very reflective definitions of Kāla. These ideas reverberate with the contemporary notion of time.

Two types of Dravyas (matter) have been described in the Āyurvedic texts, i.e. Kāraṇa Dravya (causal matter) and Kārya Dravya (effectual matter). Kārya is Vyaktāvasthā (manifested stage) and Kāraṇa is Avyaktāvasthā (unmanifested stage). It is only the transformation of form or stages (1).

Kāraṇa (causal) — there are nine Kāraṇa Dravyas, which constitute the building-blocks for all the transformation in the universe. They are Pañca Tanmātrās (subtle forms of five elements) — Ākaśa (Ether), Vāyu (Air), Agni (Fire), Jala (Water) Pṛthvī (Earth) with Mana (Mind), Ātmā (Consciousness), Kāla (time) (2) and Diśa (space).

Kārya (effectual) — all the visible and invisible matter of the universe constituted from Kāraṇa Dravyas are Kārya Dravyas. These are innumerable.

Kāla was characterised by Maharṣi Suśruta as Swayambhu (it originated itself), Anādi-madhyanidhanaḥ (it is without beginning, peak and end). It is mobile in the Sūkṣmatama Kalās (does not stop in the subtlest fractions) (3).

According to Ācarya Caraka, Kāla is the process of Pariṇāma (transformation) (4). Since Āyurveda is a science of life, the division of Kāla is important. It finds application in various ways pertaining to wellness and illness.

On a broader scale, Kāla can be divided as:
Nityag Kāla (general scale of time as day-night, seasons, etc.) and in a definite wedge as the stages of disease called Avasthika Kāla (5).

1. Nityag Kāla (natural cycles):
Nityag can be compared to Dainika Avasthā (day and night), Ṛtu Cakra (seasons), Ayanas (half of sidereal year) and Varsh (sidereal year). By following the dictums of Dincharyā and Ṛtucharyā, the body functions remain in sync with the external environment, which remain healthy.

a. Uttarayāna (Aadān Kāla) — during this time, the northern hemisphere of the earth faces the sun. The intensity of heat, wind velocity and dryness in the air dehydrates the body. Deha Bala (strength) is reduced gradually. The three Ṛtus of this phase are: Śiśira (peak-Winter), Vasanta (Spring), Grīṣma (Summer). Uttarayāna Kāla brings an increase in Tikta (bitter), Kaṣāya (astringent), and Kaṭu (pungent) Rasas (taste), respectively.
b. Dakshiṇāyana (Visarga Kāla) — the southern hemisphere of the earth faces the Sun and the intensity of heat drops down in the northern hemisphere. Clouds, wind and rain (Meghvāta) bring it down further. The three Ṛtus in this phase are Varṣa (rainy season), Śarada (Autumn), and Hemanta early Winter) (7).

Snighta (unctuousness) sets in the atmosphere and Āmla (sour), Lavaṇa (salty), and Madhura  (sweet) Rasas are predominant. Deha Bala  (strength) increases gradually.

2. Avasthika Kāla or Āturavasthā (the state of a disease in a patient):
Avasthika Kāla is the Vyādhi Avasthā or a particular stage of the disease in a patient. Time assumes a lot of importance in treatment. The concept of Kāla and Akāla in treatment is very relevant (8).

3. Śaṭvekṣa Kāla (six observatory aspects of time):
The six cardinal signs that are monitored, before administering medicines to a patient, are: Dina (time of the day), Rogi (patient), Auṣadha (medicines), Vyādhi(disorder), Jīrṇa Lakṣaṇa (signs of digestion of Auṣadha or Āhāra) and Ṛtu (9).

All of them in some way or the other pertain to a certain time-frame.

4. Ṣaṭkriyā Kāla (stages of disease pathogenesis):
Sussruta has divided the entire process of pathogenesis of the disease into six stages and termed it as Ṣaṭkriyā Kāla (10). They are: Sañcaya (accumlation), Prakopa (aggravation), Prasara (spreading), Sthānsaṃ śraya (localisation), Vyakti (manifestation) and Bheda (chronicity and complications).

5. Measurement of time with respect to motion since ancient times:
It was well known that time is measured with respect to motion or the passage of events. The smallest and easily perceptible notion of movement then was Akssinimessa (blink of an eye) (11).

6. Bheṣajya Kāla (Proper time for administration of Aussadha):
Auṣadha employed in a proper Kāla results in desired outcome. Ten divisions of times for the administration of medicine have been described by Caraka, Sussruta and Vāgbhaṭṭa.

Table 1-Bhaiṣajya-Kāla in Saṃhitās (12)
(Proper time for administration of ṣadha (medicines) as mentioned in texts of Āyurveda)
Caraka Saṃhitā Suśruta Saṃhitā Aṣṭāṅga Hṛdaya
6.1.Nirannam Abhakta Ananna
6.2. Prāgbhakta
Prāgbhakta Annādau
6.3. Madhya bhakta
Madhya bhakta Madhya
6.4.Prātaḥ Paścātbhakta Adhobhakta Ante
6.5.Sāyam Paścātbhakta
Antara bhakta ----
6.6.Bhakta saṃyuktam
Sabhakta Saannam
6.7. Samudga
Samudga Samudga
6.8. Muhurmuhu
Muhurmuhu Muhurmuhu
Grāssa Grāse Grāse
Grāsantara Kavalāntare
-- Niśi

6.1. Nirannam /Abhakata/ Ananna — medicine is administered on empty stomach in the morning. Food should be administered only after the medicine is completely digested.
6.2. Prāgbhakta /Annādau — the medicine is administered just before the intake of food.
6.3. Madhya bhakta /Madhya — administration of medicine in between the food is called Madhyabhakta. The person is asked to consume half of the food. This food initiates the process of digestion; it is followed by medicine intake. After this again food is consumed, which covers the medicine and prevents regurgitation of the medicine.
6.4. Prātaḥ paścāt bhakta/ Adho bhakta/ Ante — medicines are administered after food.
6.5. Sāyampaścāt bhakta / Antra bhakta — this comes under Adhobhakta. The mode of administration is defined as the administration of medicine after dinner.
Antarbhakta — the administration of food in between two meals is called Antarabhakta.
6.6. Bhkata sanyutam/ Sabhakta/ Sānnam — medicines are given mixed with food. Mixing is done either during preparation of food or with prepared food.
6.7. Samudga — Samudga refers to the administration of medicines both before and after food.
6.8. Muhurmuhu — the word Muhurmuhu means again and again, medicine is repeatedly taken with or without food.
6.9. Grāsa/ Grāsegrāse — medicines are mixed along with each bolus of food.
6.10. Graāsantara/ Kavalāntara — it means administration of medicines in between each bolus of food.
6.11. Niśi — administration of medicines at night or bed-time.

7. Dravya Saṃgrahaṇa Kāla (season for collection of medicinal plants' parts):
Different vegetative plant parts are collected in different seasons. The desired active compounds vary with the seasons and this influences the expression of pharmacological activity. If the plant parts are collected out of season, they will be Veeryaheena (lacking medicinal qualities).

Table 2-Dravya Saṃgrahanna Kāla
(seasons for collection of medicinal plants’ parts)
Prayojyāṅga (Useful part) Caraka (13) Suśruta (14)
7.1.Kānḍa (tuber) Śarada ------
7.2.Kṣīra (latex) Śarada -----
7.3.Mūla (root) Grīṣhma, Śiśira Pravṛtta
7.4. Patra (leaves) Varṣā,Vasanta ------
7.5. Śākhā (branches) Varṣā, Vasanta ------
7.6.Sāra (heartwood) Hemant Vasant
7.7.Tvak(bark) Śarada Śarada

7.1., 7.2., 7.7. Śarada — Autumn
7.3. Grīṣhma— Summer, Śiśira — peak-Winter, Pravṛtta - forepart of the rainy season
7.4., 7.5. Varṣā — rainy season, Vasanta — Spring
7.6. Hemanta — pre-Winter

Aims and obj ectives

1. To explore a fundamental principle of Kāla (time).
2. To conceptually explicate Kāla in relation to relativistic time (the modern notion).
3. To elucidate the importance of Kāla in Āyurveda.

Material and methods

1. The commentaries of the three treatises of Āyurveda
1.1 Caraka Saṃhitā
1.2 Suśruta Saṃhitā
1.3 Aṣṭāṅga Hṛdaya
2. Modern literature in physics, concerned with the Time principle, found in scientific journals, and research papers, etc.
3. Ancient Vedic philosophy literature as reviewed by Sri Aurobindo.
4. A search in the Pub Med central database was conducted.


Kāla is a fundamental principle in Āyurveda, with defining features as Eka (15), Anādimadhyanidhanaḥ, Svayambhu. The contemporary understanding of time is quite analogous to it.
According to Āyurveda, Kāla is stated as Eka. It was understood thousands of years ago that time is one field or a continuum. It is divided into seconds, minutes, and hours for a more pragmatic and realistic rationale.
Anādi Madhya nidhanaḥ
It refers to a similar interpretation of a continuum, that, which is without beginning, mid and end, space and time are truly infinite (16).

Space-time as a continuum forms the basis of Einstein’s theory of Special Relativity (17). Sūkṣmatamkalāmnalīyate (time does not stop at the subtlest fractions) — one of the qualities of time is the fact, that it is measured by motion and it also becomes evident through motion, like the earth going around the sun. The earth takes 365.25 days (1 sidereal year) for one revolution. In ancient times, the smallest evident motion for measuring elapsed time was Akṣinimeṣa (the blink of the eye). Now varied atomic movements to light years have come to be used as motions for subtle and gross time measurements. The flow of time can be tracked up to 10-9 seconds with Caseium-133 atomic clocks (18).

Einstein’s one-time teacher, Hermann Minkowski, stated that the actual time elapsed is a gap between two events as measured by a clock that passes through both the events. Two events are nothing but transformation.

Swayambhu — The view of modern physicist, Carlo Rovelli concurs that time doesn’t evolve in anything, it does not “flow”, and it just is. It’s just there, all, at once. This view of time is also consistent with the philosophical view of Eternalism.

Nature (the external environment) and the human body (internal conditions) have got their own rhythms pertaining to Kāla (time). Time has been an important factor for consideration of both illness and wellness. Knowing Kāla is important, if one wants to remain healthy.

Doṣa dominance (Cyclic dominance of bio energies in human body) — Kapha doṣa dominates in childhood, in the forenoon, in the early part of the night, and initial phase of digestion. Pitta Doṣa dominates in adolescence and middle-age, midday, midnight and mid-digestion. Vāta doṣa dominates in old-age, in the afternoon, late at night and the end of digestion.

Aadān and Visarga Kālas have their own characters of the wind, the sun and the moon. Their effect on Bala, and Rasas is clear-cut.

Deha Bala is of three types: Sahaja (constitutional), Kālaja (temporal or chronological strength, based upon seasons and age) and Yukti Kṛt (acquired). The diseases arising out Kāla Pariṇāma or temporal factors leading to old age and death are said to be irrevocable.

The time factor may be one of the aetio-logical factors. Every disorder happens due to Prajñāpradha (intellectual profanity), Asātamyendriyārtha Saṃyoga (unwholesome connection of sense organs with their objects) and Kāla Pariṇāma (seasonal and time changes — Ati Yoga, Ayoga and Mithyā Yoga).

Doṣa cycle — Doṣa Sañcya, Prakopa and Praśama rhythms also depend upon Kāla, e.g. Vāsata Sañcaya takes place in Grīṣma Ṛtu, Prakopa in Varṣā and Śamana in Śarada.

This cycle happens for the other two doṣas as mentioned in this table.

Table 3-Ṛtu Dossa Sambandha
(Relation between seasons and human bio-energies)

Tri Doṣas




Vāta Grīṣma
Pitta Varṣā
(Fall or pre-Winter)
Kapha Śiśira

Since, Āyurveda took birth in Indian subcontinent and 6 distinct seasons are found here.

Therefore, six seasons span two months each. There is cyclic relation between natural Sañcaya (accumulation-increase in magnitude), Prakopa (aggravation- accumulation intensifies) and Praśama (pacification) of dossas (bio energies) and Ṛtus (seasons).

With global warming and pollution, the time frame described for Ṛtus in ancient texts of Āyurveda has shifted a bit and the characteristics have also undergone some changes. Generally speaking,

Śiśira (peak-Winter) ensues from mid-December till mid-February-Śiśira marks the beginning of Uttarāyaṇa (Summer Solstice). During this season; the environment remains cold and windy. There is accumulation of Kapha Doṣa.

Vasant (Spring season) falls from mid-February to mid-April-Vasant is known as nature’s youth and the king of all seasons. The climate is warmer so Kapha which accumulated in Śiśira liquefies in this Ṛtu by hotter sun rays. Kapha Prakopa happens in this time of year. It leads to reduced digestive power and increases various diseases like cough, cold, sinusitis, indigestion or digestive system disorders and other allergic conditions.

Grīṣma (Summer) occurs from mid-April to mid-June-Grīṣma Ṛtu marks the beginning of summer in the northern hemisphere and it ends on the summer solstice. Dryness and hotness of season causes Vāta Sañcaya and Kapha Śamana in Grīṣma Ṛtu.

Varṣā (rainy season) occurs from mid-June to mid-August-According to Āyurveda, Varṣā Ṛtu falls in the Visarga Kāla (southern Solstice). Klinnā (moistness) increases causing Mandāgni (weakest digestive fire) and Śitata (coldness) upsurges causing Vāta Prakopa and Pitta Sañcaya.

Śarada (Autumn or Fall) befalls from mid-August to mid-October-second part of subtle sublime Dakṣiṇāyana is Śarad Ṛtu. The digestion is weak and there is a natural seasonal aggravation of acidic factors in the environment and body causing Pitta Prakopa.

Hemanta (pre-Winter) lies from mid-October to mid-December-Hemanta Ṛtu begins with Śarad Purṇimā and it continues for two months, during which the earth cools down and energy levels start surging that make us feel rejuvenated. The temperature starts plummeting slowly causing Pitta śamana.

Kālavirudhatā — diet and medicines are needed for health and should not be Kāla virudha. Otherwise they become incompatible and may lead to lifestyle disorders or CNCDs (Chronic non-communicable diseases)

Kāla and Kriyā Kāla — Suśruta has divided the entire process of pathogenesis of the disease in six stages and termed it as Shaṭkriyā Kāla. Among these progressive stages, the first three — Sañcaya, Prakopa, and Prasāra are Doṣāvasthā (sub-clinical stages).

Whereas the remaining stages — Sthāna Saṃśraya, Vyakta and Bheda are Vyādhi avasthā (when clinical signs and symptoms of any disease manifest). All these stages require time-bound intervention, otherwise the disease progresses to complications.

Kāla in germination and augmentation of medicinal plants — the season, during which the plant (intended for collection) has abundant Rasa, Guṇa, Vīrya and Gandha, is the best time. The role of ‘Kāla’ in optimisation of active principle is undeniable. Optimum time for collection of plant parts is: branches and leaves in Spring; the root in Summer/Winters; bark, rhizomes and milk (extracts) during Autumn; extracts in early Winter and fruits and flowers should be collected as per the season.

Nowadays, nature is changing her features due to increasing pollution, global warming and population explosion, etc. Hence, when studying the effects of Kāla (season), one comes across the distorted sense, which is affecting the flora and fauna globally.

Coming back to the current overview of time, renowned, theoretical physicist Carlo Rovelli remarked that, “Time is an illusion. Our naive perception of its flow does not correspond to its physical reality (19).”

Pointing to the source of time, Sri Aurobindo indicated that the Truth Consciousness is the first operative principle of the divine Supermind. It is all-pervading, all-comprehensive and all-inhabiting. Because it comprehends all things in being, in static self-awareness, subjective, timeless, space-less, therefore it comprehends all things in dynamic Knowledge and governs their objective embodiment in space-time (20).


Āyurveda's philosophical outlook on Kāla synchronises with a component of the theory of Special Relativity. It resonates with contemporary understanding of Time by theoretical physicists. It reflects that Kāla was immensely understood and used in Saṃhitā. Loka (external environment) and Puruṣa (human body) have got their rhythms related to Kāla (time). In-sync rhythms, is a healthy state for Puruṣa. This review intends to contribute to a more profound understanding of the fundamental principle of Kāla.


1. Panigrahi M, Vyas M,Baghe lAS, Vyas H, Mohanty KP. [Online] Kārya Kāraṇa Siddhānta. A review. Available from: [Accessed 21st January 2021].

2. Vaidya Kushwaha VHC. Caraka Saṃhitā. Reprint ed. Varanasi: Chaukhamba Sanskrit Sansthan Publishing; 2016, p. 18.

3. Acharya D, Das G. Suśruta Saṃhitā. Reprint ed., Varanasi: Chaukhamba Sanskrit Sansthan Publishing; 2016, p. 60.

4. Caraka Saṃhitā, p. 679

5. Ibid.,p. 597.

6. Ibid., p. 91.

7. Ibid.

8. Ibid.,p. 597.

9. Ibid.,p. 839.

10. Suśruta Saṃhitā, p. 260.

11. Tripathi RD. Aṣṭānga Saṃgraha. 3rded. Varanasi: Chaukhamba Subharti Publishing; 1993. p. 65.

12. Junjarwad AV,Savalgi PB, Vyas MK. [Online] Bhaiṣajya Kāla (time of drug administration) in Ayurveda. Critical review. [Online] Available from: [Accessed 23rd January 2021].

13. Caraka Saṃhitā, p. 857.

14. Suśruta Saṃhitā, p. 260.

15. Shivhare H.R. Padarth Vigyan. Edition 2017. Varanasi: Chaukhambha Subharti Publishing; p.56

16. Ames CH.[Online] Are Space and Time Infinite? The Affirmative Answer. Available from: [Accessed on 23rd February 2020].

17. [Online] Relativistic Time – Exactly What Is Time? Available from: [Accessed 2nd February 2021].

18. Essen L, Parry JVL.[Online] An Atomic Standard of Frequency and Time Interval: A Cæsium Resonator. Available from [Accessed 4th March 2021].

19. JaffeA.[Online] The Illusion of Time. Available from: [Accessed 4th January 2021].

20. Darshi CP. [Online] The Supreme Truth Consciousness: Concept of Space & Time by Sri Aurobindo – Vedāraṇyam. Available from: http://www. [Accessed on 28th July 2021]

Dr Jasmine Sehgal is Asst. Professor at the Samhita and Sidhanta Dept., Uttaranchal Ayurvedic Medical College, Dehradun, Uttarakhand; Dr. Bhavna Singh is Professor and Head of the Dravya Guna Dept. Principal GS Ayurveda Medical College, Hapur, U.P; Dr. Harsh Sehgal is Asst. Professor at the Dravya Guna Dept., Uttaranchal Ayurvedic Medical College, Dehradun, Uttarakhand.

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