Nightmares

A nightmare, often referred to as a horrible dream, is a disturbing dream that can elicit powerful emotions in the mind, usually terror, but also despair, anxiety, or extreme grief. However, psychological terminology distinguishes between nightmares and terrible dreams; particularly, when having a nightmare, a person may be awakened while having a horrible dream. The dream may feature uncomfortable situations, physical or mental terror, or panic. After a nightmare, a person will frequently awaken in a distressed state and might find it difficult to fall back asleep for a short while. Insomnia can result from recurring nightmares, which can disrupt sleep patterns and require medical attention.

Physical reasons of nightmares, including sleeping in an uncomfortable position or having a fever, as well as psychological ones, like stress or anxiety, are also possible. Eating before bed can potentially stimulate nightmares because it increases brain and body activity and the body's metabolism.
Between 20 and 30 percent of children (5–12 years old) and 8 to 30 percent of adults report having nightmares. The word "nightmare" has taken on a wide variety of negative connotations in everyday speech, including a dreadful scenario, a frightful creature, or a frightening person.