Why do the texts say that paścimottānāsana activates suṣumṇā and awakens the kuṇḍalinī?

It so happened in India, that spiritual practices are most often performed facing east. Accordingly, the west (conditionally) is our back, the south is the right and hot side and the north is left and cold. The Sun is associated with vital power, it rises in the east and sets (i.e. disappears) in the west. We fall asleep at sunset and our senses become silent, and they turn on at sunrise. We can see basically everything that is in front of us, on the sides, below and even sometimes from above, but we cannot see our back. We can only feel it, while there should be an inversion element, i.e. direction inward, listening to our sensations inside. The west is a symbol of the extinction of activities, the completeness of them, so it is suṣumṇā. It is also no coincidence that one of the well-known traditions, where kuṇḍalinī is worshiped in the form of the Goddess Kubjikā, is called paśchimāmnayā – the Western Doctrine. Paśchima – from paścāt (behind, the last, completed, western), therefore it is a symbol of suṣumṇā, self-absorption. Thus, paścimottānāsana is focused specifically on the direction of attention and the prāṇa in suṣumṇā along with it. This āsana is also focused on the conscious activation of suṣumṇā with pratyāhāra and the awakening of the kuṇḍalinī power.