Empousa appears on earth at midday because that was the time when sacrifice was offered to the dead… She approaches the offerings to the creatures of the lower world because she herself is one of their number.
Rohde establishes midday as the ritually sanctioned hour for chthonic sacrifice in ancient Greek practice, making it the moment when underworld beings — including Empousa and the Seivenes — legitimately cross to the upper world.
, Psyche: The Cult of Souls and the Belief in Immortality among the Greeks, 1894thesis