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The Sanskrit word ‘kala’ (also spelled as ‘kaala’ or kAla) means time. It is accepted as one among the nine fundamental elements (karana dravya) in Ayurveda [Cha.Sa.Sutra Sthana 1/48] and Vaisheshika philosophy.[1] Like an entity, kala also possesses qualities (guna) and effects (karma). [Cha.Sa.Sutra Sthana 1/49] Destruction and production of beings, the past, present, and future times are effects of kala. The word ‘kala’ is often used for time in general, period or proper time when something occurs. However, it has a broader and deeper interpretation as narrated in Ayurveda from a medical point of view. Kala is one of the ten factors of clinical examination (dashvidhaparikshya bhava). The vitiation and pacification of tridosha, dhatu, manifestation of diseases, and even management of conditions, daily and seasonal routines, etc. are influenced by kala. The strength and luster of that person are enhanced who knows suitable diet and regimen for every season and practices accordingly. [Cha.Sa.Sutra Sthana 6/3] Kala plays a key role in preventing and treating diseases in medical science in many ways. Kala is one of the bases for classifying conditions like acute and chronic diseases; and natural or timely (kalaja) and premature or untimely (akalaja) diseases. Kala has a role in drug collection, formation, preservation, and administration. Kala helps understand physiological functions as many procedures follow the circadian rhythm in the body. Thus, it is also helpful in maintaining health and understanding the etiopathology of diseases. Every drug acts by its specific pharmacokinetic, pharmacodynamic mechanisms and has definite rate of metabolism and half life. These properties elucidate the role of kala in the treatment of diseases. Difficulty in treating chronic diseases and appearance of grave prognostic signs (arishta) that are indicative of patient’s approach towards death are the factors that indicate the role of kala in prognosis of diseases.

Section/Chapter/topic Concepts / Kala
Authors Bhojani M.K.1, Sharma Raksha1, Rahul Anand1
Reviewers Mali V.2, Basisht G.3, Khandel S.K.4
Editor Deole Y.S.5

1 Department of Kriya Sharira, A.I.I.A. , New Delhi, India

2Department of Samhita-Siddhanta, C.B.P.A.C.S., New Delhi, India

3 Rheumatologist, Orlando, Florida, U.S.A. 4Arogyalaxmi Ayurveda Consultancy, Jaipur, India

5 Department of Kayachikitsa, G.J.Patel Institute of Ayurvedic Studies and Research, New Vallabhvidya Nagar, Anand, Gujarat, India
Correspondence email meera.samhita@aiia.gov.in, carakasamhita@gmail.com
Publisher Charak Samhita Research, Training and Development Centre, I.T.R.A., Jamnagar, India
Date of first publication: July 15, 2022
DOI 10.47468/CSNE.2022.e01.s09.103

Etymology and derivation

The word ‘Kala’ is formed by ‘Kakar’ and ‘Aakar’ of Kala and ‘Lakar’ of Lee dhatu. Kala means to count (kalate) and to hold or to put on (kalayaati).[2]

The subtle portion of Kala never discontinues (continuity never breaks). [Su.Sa. Sutra Sthana 6/3][3]

Due to the destruction attribute, all the creatures (bhuta) will resume their pure absolute form. [Su.Sa. Sutra Sthana 6/3][3]

These etymological derivations convey various characteristic features of kala. The continuity of kala never breaks. It infers that kala is eternal and infinite. For all the entities in the universe, their destruction is subjected to kala. After the destruction, the bhuta resume their pure absolute form.


  • Parinama [Cha.Sa.Vimana Sthana 8/48] [Cha.Sa.Sutra Sthana 11/42] (result)
  • Samwatsara [Cha.Sa.Vimana Sthana 8/125] (year)
  • Bhagawan [Su.Sa. Sutra Sthana 6/3][3](the Almighty)
  • Swayambhu [Su.Sa. Sutra Sthana 6/3][3] (self-originator)

Definition and features

The birth and growth of living beings is relative to time. Kala brings the living beings closer to death. The moment of death comes closer as time progresses, so it is responsible for compilation and briefing of all living beings in one group or one form. Thus, the meaning of kala is to brief or to condense. [Su.Sa. Sutra Sthana 6/3][3] When a person dies before old age, people often talk about his assassination by kala. Hence kala, in this way, is responsible for shortening a person's age. Kala never stops even for a moment and is always dynamic, therefore called 'kala’. [Su.Sa. Sutra Sthana 6/9][3]

Kala is devoid of any action (nishkriya). Conjunction (samyoga) to one place and disjunction (vibhaga) from another place is essential for any movement.[Cha.Sa.Sutra Sthana 1/52] This phenomenon is not possible with kala, because it is present everywhere. Kala incorporates sorrow and prosperity in all living beings. [Su.Sa. Sutra Sthana 6/3][3]

Kala is the name of ‘The Almighty’, which originated from no one. It is devoid of origin, existence, and destruction. It is responsible for generating natural and deformed rasa (six tastes mentioned in Ayurveda- madhura or sweet, amla or sour, lavana or salty, katu or pungent, tikta or bitter, kashaya or astringent) in substances. This means that all substances are devoid of rasa and potency in the initial stages of development. Rasa and potency develop after a certain duration of time. These natural rasas further get deformed as time continues and substance progresses towards senescence. Kala is the process of transformation into seasons and is thus called ‘parinama’. [Cha.Sa.Vimana Sthana 8/48], [Cha.Sa.Sutra Sthana 11/42]

Kala portrays a year (samawatsara) and the state of disease of a patient.[Cha.Sa.Vimana Sthana 8/125]

Kala is responsible for the generation of people and diseases. The universe is dependent on kala and kala is accountable for implementing all actions. [Cha.Sa.Sutra Sthana 25/25] Infact, the universe is generated from kala. Thus kala is the producer of all those substances which are produced. It is a shelter for the world.[1] Kala is responsible for determining small or younger (apara), bigger or older (para), neither younger, nor older; simultaneous (yugapat), late (chira) and early (kshipra).[1] These divisions must be understood from the perspective of rotations of earth around the sun. For example, if Ajay is older in age than Vijay, then this indicates that Ajay has witnessed more rotations of earth around the sun as compared to Vijay, hence Ajay has spent more kala on earth than Vijay and therefore Ajay is older (para) and Vijay is younger (apara). Kala is nectar (amurta), which means it is not corporeal. Corporeality is the quality of having definite dimensions.[4] Since kala cannot be bound in definite limits/shapes, it is incorporeal. All the entities which are produced (karya dravyas) are corporeal in nature. All the substances which cannot be created but are responsible for the production of entities are called ‘karana dravya’. Karana dravya are incorporeal and kala is one among them. Kala are considered incidental causes (nimitta karana) for every activity. [Cha.Sa.Sutra Sthana 1/48] Since kala cannot be produced, this means it doesn’t have any beginning (anadi); as kala cannot ever end, it is eternal and indefinite (ananta). [Su.Sa.Sutra Sthana 6/3][3] Being eternal, kala is non-destructible and non-divisible.

Time is one of the essential coordinates that is related to all the actions of the world because every action, either occurs early or late, and no action can surpass the involvement of kala in it. If the world becomes free from this control, it will become inactive.[5]

Attributes (guna) of kala

  1. Number (sankhya): It is one in number because despite their diversity, the marks of kala, viz., the cognition, ‘it is slow or late’ are the same in all places.
  2. Measure (parimana): It is indefinitely large (mahat)[4] because it does not have a definite size.
  3. Combination (samyoga) and disjunction (vibhaga): As time passes, old molecules break by a disjunction of their atoms, and new molecules form by a combination of atoms. Actions and movements of matter occur in the world as time passes. These actions or movements are associated with combination and disjunction.


Classification depending on external conditions (aupadhikabheda)

Depending on external conditions, kala has two divisions:

  1. Eternal
  2. Transient or temporary

1. Eternal (nityaga kala):

It is eternal moving time that is concerned with the day/season/year. [Cha.Sa.Vimana Sthana 8/125] It is not only used by the medical fraternity but also by common people as a calendar.

The year (samwatsar or varsha) contains two ayana (solstitial movement of sun to north or south)

a. Northward movement of sun (uttarayana or adana kala): Duration occurs when ascent of sun or northward movement of sun.

b. Southward movement of sun (dakshinayana or visarga kala): Duration when sun descends or southward movement occurs.

Each of these ayana is divided into three seasons (ritu). Each ritu comprises two months (masa). Each masa has two fortnights (pakshas) – shuklapaksha and krishnapaksha, of 15 days each. This division is assumed as Lunar metrics.

Image 1: Division of Kala in a year

2. Transient or temporary (avasthikor aturakala):

The condition of a patient changes with moving time due to various stages of disease manifestation. [Cha.Sa.Vimana Sthana 8/128]. Understanding the stages of diseases is mandatory for planning its management. Thus, kala is vital in medical sciences.

Division of time in classical literature

In the ancient era, time was calculated in various units. It is divided into units like akshinimesh, truti, seconds, minutes, hours, days, years, etc. for practical utility. The smallest unit of time is akshinimesh (also called matra). Akshinimesha is the time taken in the blinking of eye lids. Further division of time is mentioned below.[A.S.Sutra Sthana 4/5][6]

Akshinimesh = Matra (≈88.9milliseconds)

15 Matra = 1 Kashtha (≈1.6seconds)

30 Kashtha = 1 Kalaa (≈48seconds)

20 1/10 Kalaa = 1 Nadika (≈24minutes)

2 Nadika = 1 Muhurta (≈48minutes)

3 3/4 Muhurta = 1 Yama (≈3 hours)

4 Yama = 1 complete day or 1 complete night (≈12 hours)

1 Day and 1Night = 1 Ahoratra (≈24 hours)

15 Day night = 1 Paksha (1 fortnight)

2 Paksha = 1 Masa (1 month)

2 Masa = 1 Ritu (1 season)

3 Ritu = 1 Ayana

2 Ayana = 1 Varsha (year)

Sushruta classifies kala in similar manner. [Su.Sa. Sutra Sthana 6/4][3] Nimesha is considered the time required to utter a vowel.

Smallest unit of time according to Shrimad bhagavata is ‘Truti’. Truti is described in following way - the combination of two paramaanu forms an anu. Three anu combines to form a trasarenu. Trasarenu are the particles that are visible as particles when beam of sunlight enters the room through window. The time taken by the sunlight in crossing a ‘trasarenu’ is called Truti. Further classification of Truti is:

100 Truti = 1 Vedha (≈47.4 milliseconds)

3 Vedha = 1 Lava (≈0.14 seconds)

3 Lava = 1 Nimesh (≈0.43 seconds)

3 Nimesh = 1 Kshana (≈1.28 seconds)

5 Kshana = 1 Kashtha (≈6.4 seconds)

15 Kashtha = 1 Laghu (≈1.6 minutes)

15 Laghu = 1 Nadika (≈24 minutes)

2 Nadika = 1 Muhurta (≈48 minutes)

Importance of concept

Role in the classification of diseases:

Some of the diseases in Ayurveda are classified based on kala. e.g.

a. Kalaja vyadhi: These are natural diseases occurring due to old age. For example, arthritis, Alzheimer’s disease, Parkinson disease are observed in old age.

b. Akalaja vyadhi: These are unnatural diseases. For example, greying of hairs at an early age.

Similarly, the death is classified as kalaja mrityu (natural death after completing the expected lifespan) and akalaja mrityu (uncertain or premature death).

Diseases are classified as chronic (diseases of longer duration) and acute (diseases of shorter duration). Chronic diseases are more prone to become untreatable. [Cha.Sa.Sutra Sthana 10/18]

Diseases are classified into seven types. One among them is kalabalapravrittavyadhi (seasonal or time-linked diseases). [Su.Sa. Sutra Sthana 25/5][3]

Role in collection, preservation and administration of drugs:

Herbs are most potent when collected at a time of optimum potency, preserved and used before the decrease in strength (period of saviryataavadhi). The time of administration of medicine is also essential. Date of manufacturing and expiry dates are printed on the label of drugs guiding the patients to use them in a definite period of optimum potency. The physician advises the administration time of drugs because every drug has a specific half time and rate of clearance, indicating the significance of kala.

Time of administration of medicine (oushada sevanakala):

The chrono pharmacology deals with various effects of medications administered at different times. The factors like the circadian rhythm of dosha, and drug-food interactions determine the impact of medicines at other times.

Role in understanding physiology:

Many physiological functions in the body are bound to specific kala. For example:

  • Attainment of puberty at around 13 years and menopause at around 50 years in females, 21-35 days of the menstrual cycle, 38-42 weeks of gestation.
  • The development of the fetus during the gestation period and its embryological development is time-specific, where the development of various body parts occurs at specific time intervals. Example: development of the mind (manas) at 5th and intellect (buddhi) at 6th month.
  • Heart rate (70-80/min), respiratory rate (18/min), urine output (1.5-2 L/day), and other essential vitals are measured in terms of kala.
  • According to Sushruta, the body tissues become fully developed at 25 years in males and 16 years in females.[Su.Sa.Sutra Sthana 35/15][3]
  • Accumulation (sanchaya), provocation (prakopa) and pacification (prashamana) of tridosha (three body humors – vata, pitta and kapha) are confined to kala. Therefore a person must adapt his routines in different seasons. Medical practitioner too must acknowledge the relation between dosha and season before prescribing medicine.
Table 1: Relation between dosha and season
Tridosha Sanchaya Prakopa Prashamana
Vata Grishma ritu (Summer season) Varsha ritu (Rainy season) Sharad ritu (Autumn season)
Pitta Varsha ritu (Rainy season) Sharad ritu (Autumn season) Hemanta ritu (Early winter season)
Kapha Shishira ritu (Winter season) Vasanta ritu (Spring season) Grishma ritu (Summer season)

Childhood (balavastha), middle age (madhyamavastha) and old age (vriddhavastha) are the three stages of life divided by kala. The incidence of certain diseases varies with age. Some diseases that occur at different stages of life and during different seasons are called natural diseases (swabhavika roga). Few examples are hunger, thirst, senescence, death, and sleep.

Role in maintaining health:

Crucial element to attain sound health is to eat food at appropriate time. [Cha.Sa.Sutra Sthana 25/40] The strength (bala) of person is of three types - constitutional (sahaja), temporal (kalaja) and acquired (yuktikrita). Kalajabala depends on age of the seasons. [Cha.Sa.Sutra Sthana 11/36] Kala affects the health of a person as the air, sunlight and moonlight have got special features in dakshinayanakala (duration of movement of sun towards south) and uttarayana kala (duration of movement of sun towards north). The strength of the person increases in the winter season and decreases in the summer season. This indicates that to maintain health, a person must take adequate precautions at the end of summer and the onset of winter. The drugs incompatible with the season (kala virudhhaushadhi) should be avoided. For example, consumption of spicy and hot substances in summers and cold and dry substances in winters shall be avoided.

Following specific procedures at a particular time in daily routine (dinacharya) is a key factor in maintaining health. Ancient Ayurveda scholars emphasized kala at various places in the context of dinacharya (daily routines) and ritucharya (according to seasons). For example, medicated smoking (dhoomapana) during eight times (in case of vitiation of vata and kapha) after bathing, eating, tongue scraping, sneezing, brushing of teeth, inhalation of medicated materials, after application of collyrium, and after sleep. Application of collyrium once every fifth or eighth night.

Contrarily, following improper dinacharya is responsible for diseases.

Role in understanding etiopathology:

There are three etiological factors of diseases - asatmyaindriyartha samyoga (incompatible contact of the sense organs with their objects), prajnaparadha (intellectual error), and kala parinama (being out of harmony with the rhythms and cycles of nature). [Cha.Sa.Sutra Sthana 11/43]. Kala parinama may occur in three ways: firstly, atiyoga, i.e, by over-manifestation of a season (e.g. excess raining in rainy season), secondly, ayoga, i.e., lesser manifestation of a season (e.g. less rain in rainy season), thirdly, mithyayoga, i.e., unusual manifestation of a season (e.g., high temperature in winter season). The vitiation of air (vayu), water (jala), location (desha) and time (kala) may lead to epidemics (janapadodhwansha). [Cha.Sa.Vimana Sthana 3/6]

Some diseases have a specific duration of pathogenesis. Five types of intermittent fevers (vishama jwara) are described based on frequency and time of manifestation viz. continuous (santata), two times in a day (satata), alternate day (anyedyushka), every third day (tritiyaka), and every fourth day (chaturthaka).

The predominance of dosha varies with age (avastha kala) in the following manner:

Table 2: Dosha predominance at various ages
Avastha kala Doshas
Childhood (balyaavastha) Kapha dosha
Youth/middle age (madhyamavastha) Pitta dosha
Old age (jaraavastha) Vata dosha

In children, kapha dosha is dominant; it may be responsible for most cases common in children like pneumonia, cough, cold, etc. At a young age, pitta's predominance might be responsible for diseases like acne and cholelithiasis. Similarly, in old age, when vata dosha is predominant, most old-aged people suffer from insomnia, tinnitus, and joint pain.

The progression of the disease is divided into six stages. A disease progresses to an advanced stage if not treated on time. These stages are described as Shat-kriya kala as follows-

  1. Stage of accumulation (sanchaya)
  2. Stage of provocation (prakopa)
  3. Stage of propagation (prasara)
  4. Stage of localisation (sthanasamshraya)
  5. Stage of manifestation (vyaktibhava)
  6. Stage of complication (bheda)

Efforts made at early kala will prevent the progression of the disease to advanced stages of Shat-kriya kala.

Role in treatment:

Oleation (snehana) is one of the steps carried out on a patient before panchakarma (five methods of cleansing of body). The duration till which snehana should be done depends whether person has smooth bowel movements (mridukoshtha), moderate bowel movements (madhyamkoshtha) or hard bowel movements (kroorakoshtha).

  • Mridu Koshtha – 3 days
  • Madhyama Koshtha - 5 days
  • Krura Koshtha -7 days [Cha.Sa.Siddhi Sthana 1/6]

The kala for digestion of this snehana is longer if administered in more quantity (matra). The quantity of unctuous substance (sneha) that gets digested in 3 hours is called prathama matra. Similarly the quantities of sneha that require longer digestion are mentioned below. [Su.Sa. Chikitsa Sthana 31/25-29][3]

  1. Prathama matra: 3 hours
  2. Dvitiyamatra: 6 hours
  3. Tritiya matra: 9 hours
  4. Chaturthamatra: 12 hours
  5. Panchama matra: 24 hours

Various types of medicated enema (basti) are effective when given at a specific kala. Normally basti is advised in pravrit (before rains) season but can be advised at any time if a person suffers from a disease.

Time for the administration of decoction enema (niruha basti): when a patient has an empty stomach and after digestion of previous food, the best time is the afternoon.

Time for the administration of oil enema (anuvasana basti): in winter and spring - day time; autumn, summer, and rainy season- night time. [Cha.Sa.Siddhi Sthana 1/22-23]

Time for administering uttara basti - morning, during ovulation period (ritukala). [A.Hr. Sutra Sthana 11/77][7]

The suitable kala for administration of emesis (vamana) is spring season (for kapha dominant disorders), purgation (virechana) is autumn season (for pitta dominant disorders) and enema (basti) is end of summer (for vata dominant disorders). This is because vamana, virechana and basti are most efficient in pacification of kapha, pitta and vata respectively. [Cha.Sa.Sutra Sthana 25/40] Natural vitiation of kapha, pitta and vata occurs in spring, autumn, and end of summer, respectively.

Kala for nasal administration (nasya) as mentioned in ayurvedic literatures is twice a day in hiccup (hidhma), convulsion (apatanaka), loss of voice (svarabhramsha), etc and alternate days in other diseases. [A.Hr. Sutra Sthana 20/14-16][7]

As mentioned in Sushruta samhita, 100 years old ghee (ghrita) has properties of pacifying kapha-vata. It is efficient in providing strength and good for the eyes and intellect. [Su.Sa. Sutra Sthana 45/110][3]

Cauterization (agnikarma) should not be practiced in summer and autumn seasons. Bloodletting (raktamokshana) should be done in autumn.[8]

Panchakarma therapies are effective when done at optimum kala.

Table 3: Appropriate seasons for panchakarma
Season Panchakarma procedure
Shishira (January-March) Abhyanga, utsadana, murdhataila
Vasanta (March-May) Vamana, udvartana, nasya, dhuma, kavala
Grishma (April-June) Shita pralepa
Varsha (July-September) Basti
Sharad (September-November) Tiktasnehapana, virechana, raktamokshana
Hemanta (November-January) Abhyanga, utsadana, murdhataila, jentakasweda, ushnasadana, atapasweda.

Even the diet routine followed after vamana, and virechana karma (sansarjana karma) is most effective when administered at a specific kala.

Medicated enema (basti) is given a specific time in a particular duration (kala). Classifying basti is done based on the duration of days until it is administered.

Table 4: Classification of Basti based on days
Type of Basti Duration of days
Karma basti 30 days
Kala basti 16 days
Yoga basti 8 days

Current researches

1. Role of kala (time) in kayashodhana (detoxification of body). [9], [10]

Administration of panchakarma therapies at the right time, or the kala knowing its importance and utility leads to the success of the treatment.

2. Critical review on bhaishajyakala (time of drug administration) in Ayurveda.[11], [12]

Bhaishajyakala (time of drug administration) is an important principle to be considered while treating a disease. The administration time is mainly explained in relation to the intensity of the disease, strength of the patient, a specific dosha involved in the pathogenesis.

3. Study of the concept of kala in Ayurveda w.s.r. to kala as a karan dravya.[13]

Kala (time) is karana dravya. It is the cause for the birth and death of all living beings, for the disorders and excellence of the seasons, properties of substances such as taste and potency.

4. Role and rationale of kala in the field of Ayurvedic Pharmaceutics - A Conceptual Approach.[14]

A pharmaceutical preparation is the result of more than one pharmaceutical processing (samskara) collectively. Every procedure has its own importance. Among them kala is eternal and shows its impact on every atom of the universe. Simple plain water when kept in open surroundings, it undergoes various chemical changes. A small amount of CO^2 dissolves in it, and forms carbonic acid and initiates complex changes ultimately leading to its destruction. Such is the power of kala.

5. Understanding of nityagakala from a geographical perspective in India. [15]

India being a subcontinent, has diverse regional variabilities. Everywhere, since the gross diversity in geographical conditions, climatological patterns, food and culture, demands understanding all these variations is necessary. This article elaborated the understanding of this seasonal diversity in relation to geographical variations to better understand seasonal guidelines (ritucharya).

6. Physiological approach towards right time for food (aharasevana kala). [16]

The time of taking food (aharasevana kala) plays a vital role in the proper digestion, absorption and nourishment. The practice of food once a day (eka kalaashana) is highly beneficial. However, due to the present lifestyle, taking food only once a day is inconvenient. Therefore, taking food twice a day is adopted.

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