Egersis

Egersis, in medical terminology, is an extreme state of alert wakefulness, often used in the context of insomnia. This Greek word is usually translated as a rousing up, a rising, and/or an excitation.
In Christian theology it's a stand in for "Resurrection". The word "egersis" appears once in the Christian New Testament at Matthew 27:53. "Egeiro", a form of the same word meaning, appears a few times in the new testament. There has been some scholarly debate as to the exegetical interpretation of egersis with respect to the Christian resurrection.
In the theology of the ancient Greeks, the egersis was an annual festival celebrating the 'awakening' of a god/cult statue. These festivals sometimes took on a high importance. For example, Alexander the Great was prevented from making a sacrifice to Tyre's god Melqart, in part because the egersis of Melqart was supposed to happen soon. Alexander took this as a sign of disrespect and famously laid siege to the city.
References.
Note: only the aspect of Egersis in Matthew 27:53 does the source provide information on.