Witching hour is a term in occult belief that refers to the time at which creatures such as witches, demons, and ghosts are thought to appear and to be at their most powerful also is when demons pray on people. Black magic is thought to be most effective at this time. The period lasts from 3 AM to 4 AM, when there are no Catholic church services and prayers, as marked by the Canonical hours.
Adversely, the term Devil's hour applies to the hour of 2:33 AM, 3 AM or 3:33 AM, the suggestion being that this is an inversion of the time at which Christ died at Calvary.
The term may be used colloquially to refer to any arbitrary time of bad luck, or in which something bad has a greater likelihood to occur (e.g., a baby crying, a computer crashing, stock market volatility, crimes, etc.).