The resulting effect in Nightmare Disorder of the disturbed sleep due to frequent awakenings is significant distress with impairment on the occupational, social, and other areas of functioning of the individual with Nightmare Disorder. In rare cases, symptoms of moaning, talking and slightly moving during a Nightmare may be manifested. Upon waking up the person usually shows a sense of fear. Physical signs of increased heart rate, fear, anxiety and sweating are also evident. The person usually learns to fear going back to sleep, because the vividness of recalling the dream images can linger in the person's mind and makes them unable to relax and return to sleep peacefully. This situation can often encourage the symptoms of anxiety and depression to surface as well as symptoms that are associated with sleep deprivation such as daytime sleepiness, decreased mental alertness, and irritability.
Simple Nightmares can occur and it does not cause impairment on one's functioning. However due to the repetitive occurrence of Nightmares in Nightmare Disorders, it significantly affects the total well-being of the person affected.