Boiogy clock and the swara patterns:

the lunar currents ( ida ) manifested in the vibrations of breathings through the left nostril are referred  as ( Chandra swara ) and solar currents ( pingala ) manifested in the vibration of breathing through the right nostril are termed as ( surya swara ). In simple terms, when we breath only through the left nostril, the ( Chandra sewara ) is “on” active .When we breath only through the right nostril , the surya swara is active.

If we pay little attention to our breathing patterns, we will notice most of the time we breath only through one nostril, either through the left or through the right. It is only at the time of changing of this flow from Ida ( Chandra) to pingla ( surya ) I. e. left to right, or vice versa that both the swara are active for few moments. This change occurs periodically in about one to three hours time on an average. The flow of vital energy and prana is active through the sushumana Nadi at these moments. This transition takes place at characteristic timings, e.g. exactly at the moments of sunset which are of very significant importance in yoga and spiritual sadhanas.