Major depressive disorder is called by several names, including major depression, clinical depression, or unipolar depression. Depression is a disorder of the brain that leads to constant feelings of sadness, hopelessness and low energy that are so strong that you have trouble with daily life for weeks at a time. It is estimated that 6.7 percent of adults in the United States have major depressive disorder, with women twice as likely as men to suffer from it.

Depression Symptoms

In major depressive disorder, depression symptoms last for two weeks or more and are severe enough to interfere with the ability to work, sleep, study, eat or enjoy life. Symptoms may include:

  • Feeling sad or “empty”
  • Feeling worthless, hopeless, irritable, anxious or guilty
  • Loss of interest or pleasure in activities you used to enjoy
  • Feeling very tired all the time
  • Lack of energy
  • Trouble sleeping or sleeping too much
  • Overeating or not wanting to eat at all
  • Trouble concentrating or remembering details
  • Thoughts of death or suicide
  • Sometimes aches or pains, headaches, cramps or digestive problems

Other common types of depression include:

  • Dysthymic disorder, or dysthymia: Symptoms last a long time (two years or longer), but are less severe than those of major depression
  • Minor depression: Similar to major depression and dysthymia, but with less severe symptoms that may not last as long
  • Seasonal affective disorder: Major depression that occurs regularly in seasons with low sunlight
  • Postpartum depression: Major depression that occurs in women after giving birth