Octavia not only fearing for what's to come of her sister Pinkie Pie, and Bellamena, she also learns that the Mayor and his colleagues are a part of a foundation that is teeming with aggressive energy that can cause elaborate nightmarish pattern, that jitters their brain waves.

Could this be the source of Pinkie's repeating nightmares? You will find out as the spoilers remain in the respective paragraphs.