An hour or two after my school-age son has gone to bed, he sometimes wakes up from a nightmare, walks to my room and mumbles incoherently about what’s scaring him. But he seems off, and I can't get ...

Sleepwalking, or somnambulism, belongs to a family of sleep disorders called parasomnias, behaviors that hover on the boundary between sleeping and waking. Most parasomnias are tied to specific points ...