It's normal to feel down once in a while, but if you're sad most of the time and it affects your daily life, you may have depression. It's a condition you can treat with medicine, talking to a therapist, or changes to your lifestyle.
There are many different types of depression. Events in your life cause some, and chemical changes in your brain cause others.
Whatever the cause, your first step is to let your doctor know how you're feeling. She may refer you to a mental health specialist to help figure out the type of depression you have. This diagnosis is important in deciding the right treatment for you.
Your doctor might diagnose you with major depression if you have five or more of these symptoms on most days for 2 weeks or longer. At least one of the symptoms must be a depressed mood or loss of interest in activities.