Page 48 - Complete Works of Dr. KCV Volume 1

This Time-element in the Upanisad of the five Ratris or Five days is important in respect of man's own ascent and secret of holding on to the Divine Prana in the darkness or nights. This is expressed in the Visistadvaita exposition as Panchakala Vidhi - comprising abhigamana, upadana, ijya, svadhyaya and yoga. The five times of the day are to be devoted to the worship of the Divine in all his five fold aspect as the Transcendent, Vyuha, Vibhava, Arca and Antaryamin. The way of worship through doing kainkarya for God alone with one-pointed mind (ekayana) is the way to preserve the Prana in the rayi, the Soul within the body.
Thus the mystical division of Time into the two transcendent forms of Prana and Surya (Aditya), and Rayi and Candramas; and the three temporal forms of Uttarayana, Suklapaksa, and Ahas, and Daksinayana, Krishnapaksa and Ratri reveals the significance which the Mystic Consciousness had always attached to the pravritti and nivrtti paths as including and involving each other.
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It can in this context also refer to the sat-sthala doctrine of the Viarasaiva theology. But it is not as clear. But the Pancasamskaras and the five - symbols may have some reference to the five Nights. Manu indeed equate the Uttarayana with the day of devas, the Krsnapaksa with the day of the Pitrs though this is not the Upanisadic view. Obviously for Manu it was rather surprising that Suklapaksa should be granted to Aditya though the Moon it is who waxes.