The cause of depression is unclear; it is thought to be linked to certain imbalances of the brain chemicals. Many people do not seek treatment because they think they can work out the problems themselves, or they might be embarrassed. While some depression may be a normal reaction to life stressors, if depression becomes prolonged it can lead to a poor quality of life and even risk of suicide. Symptoms of depression include sad mood, tearfulness, irritability, withdrawal from friends and family, poor appetite or overeating, insomnia or hypersomnia, low energy or fatigue, low self-esteem, poor concentration, difficulty making decisions, feelings of hopelessness, and thoughts of suicide.

Depression can be treated with psychotherapy. Some types of chronic depression can also be treated with biofeedback/neurobiofeedback. Physician consultation for medication can also be made, if needed.