Final answer:
Nightmares are associated with REM sleep, while night terrors occur during stage 4 sleep.
Step-by-step explanation:
Nightmares are to REM sleep as night terrors are to stage 4 sleep.
Nightmares are vivid and often disturbing dreams that occur during REM (rapid eye movement) sleep. On the other hand, night terrors are episodes of intense fear or panic that occur during stage 4 sleep, also known as deep sleep. Night terrors are characterized by screaming, sweating, and a sense of terror, but the person usually has no memory of the event.
So, in summary, nightmares are associated with REM sleep, while night terrors occur during stage 4 sleep.