10. Tommy is a 6 year-old-boy who occasionally wakes up screaming a couple hours after he goes to sleep. He wakes up his parents and they rush in to comfort him, but he doesn't seem to be aware of...

10. Tommy is a 6 year-old-boy who occasionally wakes up screaming a couple hours after he goes to sleep.  He wakes up his parents and they rush in to comfort him, but he doesn't seem to be aware of them.  After a few minutes of screaming, he falls back asleep.   Tommy's parents are concerned and they bring up this issue with his pediatrician.  The pediatrician suggests Tommy might be experiencing night terrors which is not uncommon for his age.  What stage of sleep are night terrors associated with?