MODEL RELEASED. Nightmare or animal phobias. Abstract image of the sweaty fearful face of a man dreaming about, or suffering a phobia of, animals. A black cat, a dog, and a blue bolt of lightning are seen in this collage image. Nightmares in adults may be a side-effect of certain drugs, or may occur after traumatic experiences. They occur during REM (rapid eye movement) sleep and are often clearly remembered. Night terror occurs mainly in children during NREM sleep. Zoophobia is a persistent and irrational fear of animals, most often of dogs, spiders or snakes. Animal phobias usually start in childhood. Seeing the feared animal usually triggers anxiety and even panic.