 There are some evidences about the role of pranayam and role of prana basically. There are lot of actually research studies on the impact of pranayam, but how to locate pran and how to study pran in a objective, very fable and more positivist way that is a big question because it is subtle, it is not fully objective and we can look at its impact. So, there are only inferential methods through which we can get sense of what pran is and we can prove the existence of prana. So, in the 2018, this is the sixth edition of Fundamentals of Complementary, Alternative and Integrative Medicine, there is a chapter written by Staples. Staples compiles various studies which point out the existence of pran and for the convenience we can club these research findings into the three streams. There are studies which suggest that right and left cerebral hemisphere of the brain are connected with the right and left nostril breathing. So, there are some easy reading based studies which suggest that when the right nostril breathing take place, the left hemisphere becomes more active and when the left nostril breathing takes place, the right hemisphere related activities and the part of the right hemisphere shows more activity. To corroborate this idea, we all know that left hemisphere or what we call loosely called left brain is more related to the logical thinking, verbal abilities and right brain thinking is more about lateral thinking, more creative thinking related to imagination working with the space etcetera. So, the subsequent research looked at the impact of right and left nostril breathing on verbal ability and the spatial test and the scores in the spatial text, the hypothesis was substantiated. So, left nostril breathing enhances score in the spatial test scores and right nostril breathing enhances the scores in the verbal ability test. So, this is a kind of a validation of the life of the differential impact of the right nostril breathing and left nostril breathing which is the fundamental aspect of the pranayama. Another example is given about the ultradian rhythms, ultradian rhythms are the rhythms of the internal organs like kidney or pancreas and the rhythm of these internal organs are found to be connected with the different nasal cycles. So, these are three examples which suggest that right nostril breathing and left nostril breathing have differential impact of course, the complementary impact, but of course, the distinct impact on our body system and as we move further we will see these nasal cycles have impact on our emotional makeup as well. I remember I was offering this session to the group of doctors in I am Ahmadabad. Thanks to Dr. Rajesh Chanwani who invited me to conduct this session for the doctors and there when I was explaining the right nostril breathing and left nostril breathing and the differential impact there was a sense of puzzlement in the room because most of the medical professionals look at the fact that ultimately air whether it is taken from the either of the nostril goes to the same sac. So, how come it can have a differential impact, but these studies suggest that these are having the differential impact. Nonetheless this suggests that the idea of Chandranadi and Surinadi from here onwards things become even more subjective things become even more difficult to validate objectively because Nadi's as mentioned earlier are the channels through which the life energy flows that is the that is an idea about the pranic structure of our body, Eda, Pingala and Sushumna. These are supposed to be three principal Nadi's or principal channels, Eda is connected to Chandraswar or left nostril breathing, right nostril breathing is called Suraswar and it is connected to Pingala. Then Eda and Pingala are in the perfect balance energy flows through Sushumna which is in between these two Nadi's. So, that is the next step in the pranic system as explained in the yogic literature as explained in many other literature what was referred just now. There are some other sets of references which suggest that Pran is a source of energy which is distinguishable from the more physical sources of energy and these examples are taken from the book of Dr. Stephen Parker. He mentions three things movement without muscle tension. So, he gives example of Swami Vedabharti in USA he was conducting a session on biofeedback and he allowed a doctor to fix the instrument which assess the muscle tension in the body. When the reading was seen by the doctor, doctor became little puzzled and afterwards he started chuckling and Swami Vedabharti asked what is his amusement, why he is chuckling and the doctor said that your reading of the muscle tension is similar to that of a corpse almost like a dead man has so low muscle tension. But here is Swami Vedabharti who is standing, who is explaining the concept, who is using the blackboard writing things all normal activities, but muscles were so deeply relaxed. So, Stephen Parker infer that this is the sign of Prana and suggest that other than the normal objectively verifiable energy there is another form of energy when it is active it can sustain the physical body and body was sustained because of that energy called Prana which cannot be captured by the instrument which is made to assess the muscle tension. So, there is a very off-coded experiment conducted in 1964 led by rather observed by Dr. Kothari and the colleague. So, this experiment was about a Sadhu who was who sat under the earth surface all surrounded by the mud and gradually his life vital signs start coming down it reached to the level which was similar to a dead body, but at this stipulated period of time after few days when this hole was opened up and there was no way he could get oxygen and supplies of water etcetera gradually his at this stipulated time his life signals is started coming back. So, this is one of the great puzzles of science there is another set of examples which is about brain waves. So, when we are conducting something when we are doing something a different kind of brain waves are emitted through our brain predominantly these for example, we are in a very resting stage a different kind of brain pattern emerges when we are when our brain is highly active another very different kind of brain waves emit. There are Yogis and there are studies which suggest that beta brain wave which are which are emitted in a deep restful states are emitted by the brains of Yogis when they are in a waking consciousness and carrying out the normal day to day activities sometime even carrying out intellectually demanding activities. So, these examples suggest that that the form of energy which is objectively very fable is not the only energy available to us and based on these we can infer that there is a another form of energy which is not objectively very fable as of now and that can be called Prana. That is why this beautiful picture taken from this website akramyog.co.uk it compares the Chandranadi and Suryanadi with Shakti and Shiv Shakti is the energizing aspect of self Shiv is reflection of the calming aspect of self and left and right nostrils are connected to Chandranadi or Suryanadi and this is the pictorial representation actually very symbolic and represented in a beautiful with the beautiful symbol of Shiv and Shakti.