The predominant complaint is difficulty initiating or maintaining sleep, or nonrestorative sleep, for at least 1 month that is associated with daytime fatigue or impaired daytime functioning.

The sleep disturbance (or daytime sequelae) causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.

The insomnia is judged to be related to another Axis I or Axis II disorder (e.g., major depressive disorder, generalized anxiety disorder, adjustment disorder with anxiety) but is sufficiently severe to warrant independent clinical attention.

The disturbance is not better accounted for by another sleep disorder (e.g., narcolepsy, breathing-related sleep disorder, a parasomnia).

The disturbance is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition.