Eugene O'Neill's works were deeply influenced by his family experiences, particularly the tumultuous relationships within his household. Growing up with a father who was an actor and a mother battling addiction, O'Neill grappled with themes of loss and despair in his plays. His struggles with mental illness and alcoholism also shaped his perspective on human nature and suffering. The exploration of complex family dynamics became a hallmark of his writing, allowing audiences to connect with the raw, human emotions portrayed in works like "Long Day's Journey Into Night," creating a legacy of profound theatrical storytelling.