Why does a nightmare disappear as soon as one recollects the Buddha during a nightmare?

Question: Why does a nightmare disappear as soon as one recollects the Buddha while having it? 

Answer: When the mind consciousness recollects the Buddha in daily life, it permeates and transforms the manas, so that the manas holds the Buddha in its heart and also understands the benefits of recollecting the Buddha. When encountering a dangerous situation in a dream, it directly raises the thought of the Buddha and utters the Buddha's name—the name comes out spontaneously, without the mind consciousness needing to deliberate and then decide to recollect the Buddha. This is true recollection of the Buddha (buddhānusmṛti), and it can evoke a response from the Buddha. Once the Buddha's power blesses and protects, the nightmare disappears. The environment changes according to the mind; as soon as the mind of recollecting the Buddha appears, the nightmare realm vanishes, and the suffering transforms into peace and tranquility.