Bullying takes many forms and involves an imbalance of power, often occurring repeatedly over time. It can include name-calling, isolation, physical assaults, verbal threats, harassment, intimidation, and cyberbullying. The effects of bullying can be severe and long-lasting, including depression, drug and alcohol abuse, self-harm, suicide, violence, anxiety, sadness, loneliness, lack of sleep, eating changes, loss of interest, mental health problems, and dropping out of school. Many celebrities like Demi Lovato and Justin Timberlake have experienced bullying themselves as children and teenagers.