text: Nervous breakdown: What is it?\nWhat is a nervous breakdown? What causes people to have them?\n- Linda / Minnesota\nMayo Clinic psychiatrist Daniel Hall-Flavin, M.D., and colleagues answer select questions from readers.\nAnswer\n\nNervous breakdown is a term that the public uses to characterize a range of mental illnesses. It's not a medical term, and it doesn't indicate a specific mental illness. Generally, it describes a person who is severely and persistently emotionally distraught and unable to function at his or her normal level.\n\nOften, when people refer to having a nervous breakdown, they're describing severe depression. Signs and symptoms of severe depression include:\n\n    * Agitation or restlessness\n    * Difficulty or inability to stop crying\n    * Sleeping difficulties\n    * Indecision\n\nThe causes of mental illness usually aren't clear. But these factors may play a role:\n\n    * Stress\n    * Drug and alcohol use\n    * Co-existing medical conditions, such as thyroid disorders and certain vitamin deficiencies\n    * Genetics\nhttp://www.mayoclinic.com/health/nervous-breakdown/AN00476