Interaction with AI companions and psychological well-being.

As large-language-model-enhanced chatbots become increasingly expressive and socially responsive, many users begin forming companionship-like bonds with them. This study investigates how using AI companions relates to psychological well-being. We collected self-reported data from 1,131 US adults who use Character.AI, including survey responses and 4,664 chat sessions (464,687 messages) from 237 participants. By triangulating self-reported usage, relationship descriptions and real chat histories, we identify patterns of engagement and associated outcomes. Smaller social networks were associated with reporting companionship as the primary chatbot use (β = -0.03; 95% confidence interval (CI), (-0.05, -0.01)), which in turn was associated with lower well-being (β = -0.48; 95% CI, (-0.70, -0.25)). For self-reported companionship usage, this association was stronger when interactions were intensive (β = -0.31; 95% CI, (-0.56, -0.06)) and highly disclosive (β = -0.38; 95% CI, (-0.63, -0.14)). These results suggest that the association between AI companionship and well-being is not uniform and depends on users' offline social environments and how chatbots are used.