The lesser intensity of the REM anxiety dream may be at least partially explained by the fact that during REM the physiological activation provides a buffer which prevents extreme terror. This physical movement also helps the body awaken to avoid the nightmare altogether and awaken the dreamer. The nightmare provokes a retaliatory response, both in dream content and in actual physical movement. The resulting body movement is usually sufficient to cause an awakening. Therefore it seems that even though our mind is putting us through a nightmare the dreaming is helping us fight against the scary situation by giving us physical movement to wake ourselves up.
Night terrors differ from nightmares in many ways.
These two types of anxiety dreams reflect the characteristic differences between an awakening from REM sleep and on awakening from the deep sleep stage of non-REM sleep. As we already know nightmares take place during the REM while night terrors take place within the deepest level of NREM sleep. The night terror is usually an event of the early part of the night when most stage 4 is present, while the nightmare can take place in any REM period. Another area where these two parasomnias differ is that people waking up from a nightmare are fully aware they were dreaming while people from night terrors wake up confused, disoriented, and drowsy. The individual is usually unaware of what has just occurred.