Night terrors (sleep terrors) consist of sudden arousals from slow wave sleep (Stage 3) accompanied by screams or crys or severe fear.  The patient has amnesia for the event and are inconsolable. The event usually occurs in the first part of the night.  They usually subside by adolescence and are rare in adults.  Nightmares or dream anxiety attacks occur in the REM stage of sleep and are usually in the latter part of the night and associated with complex dreaming mentation.