Human: How do I know if my teen is abusing drugs? Assistant: 
If your teen is exhibiting any of the following signs, it's possible they are abusing drugs: changes in behavior and mood, including irritability or depression; difficulty sleeping or excessive sleepiness; poor concentration and memory problems; increased risk-taking behaviors; risky sexual behaviors; using more alcohol or other substances than usual. It's also important to pay attention to physical symptoms such as frequent nosebleeds, headaches, or stomachaches.