Night terrors, also called sleep terrors, occur during deep non-REM sleep within an hour of falling asleep. During a night terror, the person may sit up and appear terrified with their eyes open but are still asleep. They usually do not remember the episode and cannot be comforted. Night terrors are more common in children aged 2 to 6 and occur due to increased brain activity, often being triggered by stress, illness, or tiredness. Parents should comfort and ensure the safety of a child having a night terror without waking them up.