nervous breakdown
noun /ˌnɜːvəs ˈbreɪkdaʊn/
  /ˌnɜːrvəs ˈbreɪkdaʊn/
 (also breakdown)
- a period of mental illness in which somebody becomes very depressed, anxious and tired, and cannot deal with normal life- to have/suffer a nervous breakdown
- The stress of her job had brought her to the brink of a nervous breakdown.