1. Either of the following must be present:

   1. persistent and distressing complaints of feelings of exhaustion after a minor mental effort (such as performing or attempting to perform everyday tasks that do not require unusual mental effort);
   2. persistent and distressing complaints of feelings of fatigue and bodily weakness after minor physical effort;
   At least one of the following symptoms must be present:
   1. feelings of muscular aches and pains;
   2. dizziness;
   3. tension headaches;
   4. sleep disturbances;
   5. inability to relax;
   6. irritability

The patient is unable to recover from the symptoms in Criterion A (1) or (2) by means of rest, relaxation, or entertainment.
The duration of the disorder is at least 3 months.
Most commonly used exclusion clause. The disorder does not occur in the presence of organic emotionally labile disorder, postencephalitic syndrome, postconcussional syndrome, mood disorders, panic disorder, or generalized anxiety disorder.