Bedtime Distress in a 7-Year-Old Boy: Your Dx?

The parents of a 7-year-old boy are alarmed by his sudden loud screaming and crying shortly after he falls asleep. He sits up in bed, seems very distressed, and does not wake up when touched or gently shaken. On rare occasions, he wakes up, appears confused, and has no recollection for the events. His recent pediatric workup was all within normal limits and your physical evaluation is unrevealing.