At 2 a.m., a 15-year-old sits on her bed, phone glowing in the dark. She doesn’t want to wake her parents. So she types into a chatbot to ask questions she’s never said out loud. The responses come quickly. Calm. Reassuring. Always there. But here’s the truth: she doesn’t know who, or what, is answering back. And neither do we. Across the country, more teens and young adults are turning to AI chatbots for something that looks and feels like mental health support.