From Longman Dictionary of Contemporary Englishprey on somebody/something phrasal verb1 HBAif an animal or bird preys on another animal or bird, it hunts and eats it → predator Cats prey on birds and mice.2 TRICK/DECEIVEto try to deceive or harm weaker people religious cults that specialize in preying on young people3 prey on somebody’s mindWORRIED to make someone worry continuously The accident has been preying on my mind all week. → prey→ See Verb table
Examples from the Corpus
prey on somebody’s mind• But his main preoccupation was with the unfinished Requiem, which had begun to prey on his mind.• Important items which are left have a habit of preying on the mind.• It was Tatiana preying on his mind.• It began to prey on my mind so much that I went to the casualty department of Charing Cross Hospital. 