Night terrors, also known as sleep terrors, are a type of sleep disorder that causes feelings of panic or dread and typically occur during the first hours of stage 3-4 non-rapid eye movement (NREM) sleep and last for 1 to 10 minutes. They are classified as a parasomnia, which is an undesired occurrence during sleep. Night terrors are different from nightmares in that the person experiencing a night terror remains asleep and usually does not remember the episode in the morning. During a night terror, a person may suddenly sit upright in bed, act very upset and afraid, shout out or scream in distress, and exhibit signs of fear while still asleep, including screaming and kicking. Night terrors can be alarming to see, but they are not harmful and kids almost always grow out of them. Night terrors are most common in children, but adults can also suffer from them. Factors that may contribute to night terrors include fever, stress, sleep deprivation, light or noise, an overfull bladder, and spending the night somewhere unfamiliar.