The ideal condition for meditative practice occurs when the flow of air in each nostril is the same. This balance arises when the predominance of flow in the left nostril changes over to predominance in the right nostril or vice versa. This changeover occurs periodically in accordance with the ultradian rhythm that we discussed briefly. This cycle is said to repeat itself every 90 minutes, but in fact there are many other factors involved which tend to greatly modify it, making it shorter or longer and subject to extreme variability. This variation or fluctuation is especially noticeable with people who live in busy towns and cities who are subjected to a continuous stream of external stimuli and social pressures. The rhythm tends to be more constant and nearer the 90minute cycle with people living closer to nature in villages and the quieter parts of the world.
The best time for meditative practices occurs naturally for a few minutes throughout the day and night, when the ida breath flow changes over to the pingala breath flow or vice versa. But most people never notice this changeover because they are too busy. Therefore, they rarely take the perfect opportunity to utilize this short period of time to become aware of their being. This does not mean that you will automatically start to meditate at this period; it means that this is the ideal condition under which one’s being, is most receptive to the meditative state – pure awareness.
In nadi shodhana pranayama and other yogic practices, the two breath flows are artificially rendered equal, helping to induce the ideal situation for meditation. Therefore, it is highly recommended that the two breath flows be balanced before attempting any meditative techniques. Under this condition there is a balance between wakefulness to the outside world and total absorption or sleep in the inner psychic world of the mind.