Night terrors, also known as sleep terrors, are episodes of intense fear, screaming, flailing, and kicking while still asleep. They are classified as a parasomnia, which is an undesirable behavior or experience during sleep. Night terrors are different from nightmares, as the person who has a night terror episode remains asleep and usually does not remember anything about it in the morning. Night terrors are most common in children, but adults can also suffer from them. A normal attack typically lasts between 30 seconds and 3 minutes, but they can be substantially longer. Night terrors are not usually a cause for medical concern, but they may require treatment if they cause problems getting enough sleep or pose a safety risk. Night terrors in adults are often linked to stress, trauma, or a condition that affects sleep, such as obstructive sleep apnea, restless legs syndrome, or migraines.