For years, Dr Jean Twenge warned about the links between declining mental health and the rising use of smartphones and other devices. She was one of the first to raise the alarm, now she wants to offer parents some solutions. Dr Twenge says parents are up against tech companies that do everything they can to encourage young people to spend as much time as possible on their phones and laptops and having conversations with them about that are not going to cut it. Teenagers need rules. She writes not just as a renowned researcher, but as a parent of 3 teenage daughters. Her latest book is called 10 Rules for Raising Kids in a High-Tech World: How Parents Can Stop Smartphones, Social Media, and Gaming from Taking Over Their Children's Lives.