I feel extremely sad and upset a lot and often cry myself to sleep but o can't seem to think of anything that wrong in my life what is this?? Its disturbing me and I feel very tired at school?

You could be depressed. Depression is an imbalance of certain chemicals in your brain that causes these emotions. It isn't always triggered by a sad event, or something wrong in your life. I suggest talking with a counselor, or your parents. Just let them know that you think you may be a bit depressed and would like to know how to get some help. A counselor can give you self-help exercisesto give you a little happieness boost. If they feel it is necessary they may also give you some medicine to help. Best of luck and every happieness to you!

You are a teenager, it happens sometimes, you have hormones and new things to deal with in your life as you get older! Is there someone you can talk to? Sometimes it just feels better to talk, even if you don't know what's bothering you, just to have someone listen might make you feel better, a school counseler perhaps? If you start feeling worse or like hurting yourself please please seek help