Ayurveda teaches that the Three Doshas; Vata, Pitta and Kapha reflect themselves appropriately around each 24 hour day/night period in a biorhythmic pattern. Prana flows through the body, through the organs, channels and systems in concert with the energy required in these and hence allowing the 5 Elements and their constituent 3 doshas to also function. Symptoms relating to a particular dosha may then also appear at its most appropriate time.(1) So, obviously there is a correlation between Prana, 3Doshas, organs etc.
In ancient times there were no watches or clocks, the only reliable marker of time was the hour of noon, sometimes also called mid-day. Whereas sunset and sunrise may vary greatly, according to the different stages or seasons of the year, so the only dependable reference from which we can work is mid-day or noon.
Since then, today we recognise this time as 12:00 noon, when the Sun is the highest and directly above, where there is no obvious shadow on the ground. This is the hottest part of the day, probably until just after 2:00 pm because heat from the Sun is trapped in the atmosphere and on the surface of the Earth. Heat continues building up after noon, when the Sun is highest in the sky.
However, by 3:00 pm or so, the Sun is then low enough in the sky for outgoing heat to be greater than incoming heat in the atmosphere and so the temperature then may generally drop. The peak of Pitta as a dosha is at midday when the Sun is directly above and this time of 12:00 noon is the strongest heat for the body. According to Ayurveda, this peak period lasts for 4 hours after which Pitta goes back to its regular level. Ayurveda today as a consensus officially relates this period of time between 10:00 am and 2:00 pm to Pitta, and its midpoint or peak at 12:00 noon.
For a Pitta person, it is important at this time to not exceed his/her bodily Pitta levels by standing in the Sun for too long or by eating excessively hot/spicy dishes or undertaking rigorous activities directly in the sunshine. Midday lunch is indeed the most important meal of the day, when the Sun and the heat of the natural environment supports the digestive fire (jathara agni).
Additionally, Ayurveda explains that each dosha is also reflected twice during a 24hour period or day, twelve hours apart. This means that Pitta as a dosha is not only reflected during noon (primary Pitta) which today we can allocate a period of four hours but also during midnight for four hours (secondary Pitta).
Charaka explains this as Pitta: “during the mid-day, [and] mid-night.” (3)
According to Ayurveda, the previous dosha to Pitta (noon) must therefore be Kapha (am) and the following dosha to Pitta must be Vata (pm). Each dosha has a 4-hour period of activity, once in the early morning- noon and once at evening-night for a total of 24 hours for the 3 doshas. They occur as such: primary doshas (am) Vata, Kapha, Pitta : secondary doshas (pm) Vata, Kapha and Pitta. Each one peaking for 4 hours and totalling 24 hours.The primary doshas are those appearing or reacting during early morning (2:00 am) till early afternoon (2:00 pm) while the secondary doshas are those that are reflected during early evening (2:00 pm) to early morning (2:00 am).
Charaka in the Nidanasthana chapter explains this not by the hour as we do today but rather described this by periods of time related to the Sun, eg ‘fore-noon, after-noon, mid-night, mid-day’. He utilises a fever whether caused by Vata, Pitta or Kapha as a physical symptom which may be readily measured or felt in a patient and will show up at these times.
“Symptoms of Vata fever: occurrence or aggravation in the after-noon [or] during dawn.” (2)
“Symptoms of Pitta fever: simultaneous manifestation or aggravation in the entire body during the mid-day, [and] mid-night.” (3)
“Symptoms of Kapha fever: simultaneous manifestation or aggravation in the entire body during the fore-noon, [and] in the evening.” (4) Charaka Samhita, Nidanasthana
It is by this time of 12:00 noon that pranic energy has already peaked in the heart and its 2 dhamanis, protecting /strengthening the organ from the peak of heat/Pitta. In a similar way, prana starts its increase and then peaks in the Small Intestine at 1:00 pm. Over an hour or so, prana begins its decrease in the Small Intestine until it returns to its normal level at 2:00 pm. This extra energy in the Small Intestine for 2 hours ensures that food can be digested properly with sufficient Agni (jathara) to break down and digest the nutrients.
A number of studies have shown that people who eat a normal lunch before 3:00 pm are more likely to loose weight compared to those who eat after 2:00 pm (the beginning of the Vata period) and therefore they gain weight because digestive fire or jathara agni is now not as powerful as before 3:00 pm.
“51% of the subjects were early-eaters -lunch time before 3:00pm and 49% were late-eaters- after 3:00pm, respectively. Late lunch eaters lost less weight and displayed a slower weight-loss rate during the 20 weeks of treatment than early-eaters.” (5) Timing of food intake predicts weight loss effectiveness, Prof. Marta Garaulet et al.