Long before acoustics came to be understood in Europe as a subject of study, the ancient Arab, Greek and Indian civilizations were already familiar with the therapeutic role of sounds and vibrations and the later day concepts pertaining to them. While music as a whole is well recognized for its entertainment value, the Indian civilization had gone a step forward to attribute the curative aspect to music.

The ancient system of Nada Yoga, which dates back to the time of Tantras, has fully acknowledged the impact of music on body and mind and put into practice the vibrations emanating from sounds to uplift one's level of consciousness. It is the Indian genius that recognized that ragas are not just mere commodities of entertainment but the vibrations in their resonance could synchronize with one's moods and health. By stimulating the moods and controlling the brain wave patterns, ragas could work as a complementary medicine (Sairam,2004 a & b).

What is a Raga?
Raga, we all know is the sequence of selected notes (swaras) that lend appropriate 'mood' or emotion in a selective combination. Depending on their nature, a raga could induce or intensify joy or sorrow, violence or peace and it is this quality which forms the basis for musical application. Thus, a whole range of emotions and their nuances could be captured and communicated within certain rhythms and melodies. Playing, performing and even listening to appropriate ragas can work as a medicine.(Bagchi, 2003) Various ragas have since been recognized to have definite impact on certain ailments. (Sairam, 2004b)

Historic References on Raga Chikitsa.
The ancient Hindus had relied on music for its curative role: the chanting and toning involved in Veda mantras in praise of God have been used from time immemorial as a cure for several disharmonies in the individual as well as his environment. Several sects of 'bhakti' such as Chaitanya sampradaya, Vallabha sampradaya have all accorded priority to music. Historical records too indicate that one Haridas Swami who was the guru of the famous musician in Akbar's time,Tan Sen is credited with the recovery of one of the queens of the Emperor with a selected raga.

The great composers of classical music in India called the 'Musical Trinity', - who were curiously the contemporaries of the 'Trinity of Western Classical Music, Bach, Beethoven and Mozart– were quite sensitive to the acoustical energies. Legend has it that Saint Thyagaraja brought a dead person back to life with his Bilahari composition Naa Jiva Dhaara. Muthuswamy Dikshitar's Navagriha kriti is believed to cure stomach ache. Shyama Sastry's composition Duru Sugu uses music to pray for good health.

Raga chikitsa was an ancient manuscript, which dealt with the therapeutic effects of raga. The library at Thanjavur is reported to contain such a treasure on ragas, that spells out the application and use of various ragas in fighting common ailments.

Raga Chikitsa: Raga Therapy in India
Living systems show sensitivity to specific radiant energies – be it acoustical, magnetic or electro-magnetic. As the impact of music could be easily gauged on emotions and thereby on mind, it can be used as a tool to control the physiological, psychological and even social activities of the patients

Indian classical music can be classified into two forms: kalpita sangita or composition, which is previously conceived, memorized, practised and rendered and manodharma sangita or the music extemporised and performed. The latter can be equated to the honey-mooner's first night as it conceives both spontaneity and improvisation. It is fresh and natural as it is created almost on the spot and rendered instantly on the spur of the moment.

According to an ancient Indian text, Swara Sastra, the seventy-two melakarta ragas (parent ragas ) control the 72 important nerves in the body. It is believed that if one sings with due devotion, adhering to the raga lakshana (norms) and sruti shuddhi, (pitch purity) the raga could affect the particular nerve in the body in a favourable manner.

While the descending notes in a raga (avarohana) do create inward-oriented feelings, the ascending notes (arohana) represent an upward mobility. Thus music played for the soldiers or for the dancers have to be more lively and up lifting with frequent use of arohana content. In the same way, melancholic songs should go for 'depressing' avarohanas. Although it is not a rule, most of the Western tunes based on major keys play joyful notes, while those composed in minor keys tend to be melancholic or serious.

Certain ragas do have a tendency to move the listeners, both emotionally as well as physically. An involuntary nod of the head, limbs or body could synchronize with lilting tunes when played.

Some Therapeutic Ragas
Some ragas like Darbari Kanhada, Kamaj and Pooriya are found to help in defusing mental tension, particularly in the case of hysterics. For those who suffer from hypertension, ragas such as Ahirbhairav, Pooriya and Todi are prescribed. To control anger and bring down the violence within, Carnatic ragas like Punnagavarali, Sahana etc. do come handy.

This author, experimenting on the impact of raga on mentally-retarded (MR) children have noticed that it is the right combination of rhythms and tempo, which also affect the quality of a raga.

Not only psychological impact, but also somatic or physiological impact of ragas has come to light in some recent works. (Sairam, 2004b). For instance, stomach-related disorders are said to be cured with some Hindustani Ragas such as Deepak (acidity) , Gunkali and Jaunpuri ( constipation) and Malkauns or Hindolam (intestinal gas and for controlling fevers). Fevers like malaria are also said to be controlled by the ragas like Marva. For headaches, relaxing with the ragas like Durbari Kanada, Jayjaywanti and Sohni is said to be beneficial.

Conclusion
There is a growing awareness that ragas could be a safe alternative for many medical interventions.

Simple iterative musical rhythms with low pitched swaras, as in bhajans and kirtans are the time-tested sedatives, which can even substitute the synthetic analgesics, which show many a side-effect. They are capable of leading to relaxation, as observed with the alpha-levels of the brain waves. They may also lead to favourable hormonal changes in the system. (Crandall, 1986).

It is therefore felt that there is an urgent need for further detailed enquiry to be based on scientific parameters, which will go a long way in unearthing the goldmine on which the Indian musical system is resting now.

For this purpose, it is necessary that a group of exponents in Indian ragas join experts in medicine to help evolving a scientific system of raga therapy for the most common illness of the modern times: stress and stress-related disorders. Our leaders, professionals and managers all suffer from stress, thanks to the ever-increasing man-machine interface, resulting in the machine making the man to behave!