And I'm not (just) talking about feelings.
A stereotype is defined as "a widely held but fixed and oversimplified image or idea of a particular type of person or thing". That's pretty wordy, but we've all encountered stereotypes before. We make assumptions about people based on their race, gender, class, sexuality, weight... pretty much anything about our identity is fodder for stereotypes. They don't have anything to do with how we as individuals behave- that's why they're assumptions. And I think we can all agree that being stereotyped is at least annoying. Instead of getting to know you, people just assume you're going to think or act a certain way? Ugh. Well it turns out that stereotyping isn't just irritating- it can actually have adverse health effects.
Stereotypes make people sick!
I know, everything makes us sick these days. A national study found that people who felt judged by stereotypes "were more likely to have hypertension, to be depressed, and to rate their own health more poorly" (via). People who experience racial profiling and discrimination are more likely to suffer from cardiovascular disease, breast cancer, and have a higher mortality rate (via). Research has also found that experiences of discrimination are a form of stress that can result in anxiety and even PTSD (via). So stereotypes aren't just about hurt feelings, prolonged exposure to discrimination can literally kill you, albeit slowly.
It doesn't stop there either!
Racial bias doesn't just have an internal effect. When people buy into stereotypes, it changes the way we interact. For example: Doctors and nurses interpret the pain of black patients as less severe than that of white patients, and as a result they give their black patients less accurate treatment recommendations (via). Stereotypes lead to prejudice which leads to things like hate crimes, disproportionate use of police force, and an overall culture of violence. Which probably doesn't help with that hypertension problem.
Don't buy into stereotypes.
Generalizations, particularly negative ones, are bad for all of us. The best thing you can do is confront yourself about the ones you're hanging on to and start working to debunk them. Figure out where you picked up the assumption. Combat it by opening yourself up to messages that run counter to the belief. And when you can, hold the people around you to the same standard. This can be tricky. Confronting people about stereotypes they're spreading can encourage them to reconsider and use fewer of them, it can also lead them to respond more negatively to you, particularly if you are female and/or nonwhite (via). Use your own judgement, take care of yourself, and try to leave the world a little better than it was when you got here.