Atypical depression means feeling really down and sad, but in a different way than most people who are sad. When someone has atypical depression, they might have different symptoms than someone who has regular depression.
For example, some people with atypical depression might feel good for a little while when something good happens, like getting a good grade or seeing a friend, but then they'll feel sad again. Or they might feel like their arms and legs are heavy and hard to move, like they don't want to get out of bed or do anything. Other people might feel really hungry, especially for sweet things, and might gain weight because of it.
The good news is that atypical depression can be treated! Doctors can give medicine or recommend counseling to help people feel better. And it's important for anyone feeling sad or down to talk to a grown-up they trust and ask for help.