Night terrors are a type of sleep disorder that typically occur in children, though they can affect adults as well. During a night terror, a person may suddenly awaken in a state of extreme fear, often screaming or thrashing about. Unlike nightmares, which occur during REM sleep, night terrors happen during deep non-REM sleep, usually in the first few hours of the night. These episodes can last from a few minutes to half an hour, and the person usually does not remember the event upon waking. Night terrors are often triggered by factors such as stress, sleep deprivation, or illness. While they can be distressing for both the individual and their caregivers, they are generally not harmful and often resolve with age.