In Slavic mythology, the Notsnitsa is a nightmare spirit that also goes by the name kriksy, plaksy, plachky, plaksivicy, kriksy-varaksy, kriksy-plaksy, night hag, night maiden. She is referred to as Načnica in Belarusian, Nocnica or Płaczka in Polish, горска майка, ношно in Bulgarian, Шумска маjка, бабице, ноћнице in Serbian, mrake, vidine in Croatian, nočne more in Slovene. The Notsnitsa is also present in Russian and Slovak folklore. She is known to torment children at night, and a stone with a hole in the center is said to be a protection from the Nocnitsa. Mothers in some regions will place a knife in their children's cradles or draw a circle around the cradles with a knife for protection. This is possibly based on the belief that supernatural beings cannot touch iron. In the Roman tradition, an incubus is a demon in male form who, according to mythological and legendary traditions, lies upon sleeping women, in order to engage in sexual activity with them. Its female counterpart is a succubus. Salacious tales of incubi and succubi have been told for many centuries in traditional societies. Some traditions hold that repeated sexual activity with an incubus or succubus may result in the deterioration of health, mental state, or even death.
Folklore
The Nocnitsa is known to sit on one's chest, drawing "life energy". Because of this, many refer to Nocnitsa as a type of vampire. The Nocnitsa will often continue visiting. According to some folklore, night hags visit when one sleeps on one's back, with the hands on the chest. According to some folklore, night hags are made of shadow. She might also have a horrible screeching voice. She might allegedly also smell of the moss and dirt from her forest of origin. The Nocnitsa is almost certainly linked to the common apparition seen during the hypnagogic state of sleep.
A creature, considered by the characters to be a nocnitsa, is depicted in a 2017 horror movieSlumber.
There was a nocnitsa in the Supernatural novel 'Night Terror' by John Passarella.
In the book Coraline, by Neil Gaiman, a Nocnitsa poses as Coraline's alternate dimension mother. Coraline, however, has a stone with a hole in it which protects her.
It is often believed through out the Middle East that this mythological creature came into people's homes at night, and would watch their children sleep if they did not behave.