Depression
Everyone experiences periods of sadness from time to time. Whether it be in response to the end of a relationship, the loss of a family member or friend, or simply feeling down for no apparant reason, these mood fluctuations are most often a normal part of life. However, when sadness persists accompanied by a loss of interest, poor concentration, sleep issues, low energy, poor self-esteem, or other uncomfortable thoughts and feelings, you may be experiencing a depressive episode.
In addition to talking with your primary care doctor, it can be helpful to learn about cognitive behavioral strategies that have been shown to effectively treat depression so you can get back to feeling like yourself again.