One important element is the pacing. It shouldn't be too slow or too fast. In 'Frankenstein', the build - up to the creation of the monster and then the consequences that unfold at a certain pace keep the reader on edge. Also, having some sort of psychological aspect can make it more thrilling. In 'The Strange Case of Dr. Jekyll and Mr. Hyde', the exploration of the dual nature of man is a psychological thriller element that adds to the overall effectiveness of the story.
Unexpected twists. For example, in a story where a person thinks they are safe in their locked room, but then something comes through the walls. Also, a sense of the unknown. Like a strange noise that the character can't identify.
One important element is the setting. A spooky place like an old, creaky house or a dark forest can immediately create a sense of unease. For example, in the story of the little girl and the glowing eyes at her window, the fact that her house was on the edge of a dark forest added to the scariness. Another element is the unknown. When the reader or listener doesn't know exactly what the threat is, it's much scarier. In the story of the traveler and the shadowy figure in the inn, we don't really know what the figure is or what it wants, which makes it more frightening.
Mystery is a key element. For example, in stories where there's an unknown presence like in 'The Haunted Doll' story. You don't know exactly what the doll is or why it's acting strangely. This keeps the listener on edge. Another element is the use of the unknown environment. In the story of the abandoned house, the kids are in a place they don't fully understand. It adds to the scariness. Sound effects, even just described ones like creaking floors or strange giggles, also create an effective slightly scary bedtime story.
Effective short scary bedtime stories often have a creepy atmosphere. This can be created through descriptions of the setting, such as a dark, spooky attic or a lonely cabin in the woods. Sounds also play a big role. The howling of a wolf or strange whisperings can immediately set a scary mood. And having a menacing presence, whether it's a shadowy figure or an old doll with an eerie look, is important for making the story effective.
One element is the sense of the unknown. In long scary stories, often there are things that the characters and the readers don't understand. For example, in 'The Call of Cthulhu', the nature of Cthulhu is so alien that it creates a deep sense of unease. Another is the use of atmosphere. Dark settings like in 'The Legend of Sleepy Hollow' with its spooky woods and misty landscapes add to the fear. Also, psychological elements play a big role. In 'The Yellow Wallpaper', the slow descent into madness of the main character makes the reader feel on edge.
The element of the unknown. In quick scary bedtime stories, not knowing what's going to happen next is a big factor. For example, in a story where a character hears strange noises in an old house but doesn't know the source. It creates suspense.
The element of the unknown is very effective. For example, in a short creepy story, if there's a strange noise but you don't know what's causing it, it creates fear. It makes the reader or listener imagine the worst - like a monster or a ghost.
Isolation is also a key element. If a character is alone in a spooky place, like a girl all by herself in an old house. There's no one to help them, and that heightens the sense of fear. Also, the use of the dark and the cold. These elements are often associated with fear in our minds. When a story mentions a cold breeze on a dark night, it immediately sets a spooky mood.
The element of the unknown. For example, in a short story where you just hear a strange noise but don't know what's causing it. It plays on our fear of the unseen.
Gore can be an element, but it's not always necessary. Sometimes, psychological horror is more effective. In 'The Shining', it's not so much the blood and guts but the slow descent into madness of the main character that scares people. Creepy characters also play a role. A character like Freddy Krueger from 'A Nightmare on Elm Street' is really terrifying. He can invade people's dreams and kill them, and his burned face and clawed glove are iconic and scary images.