Insomnia Classifications: Are They Clinically Useful?

Insomnia is caused by a variety of physiologic, emotional, environmental, or behavioral conditions. As such, patients with insomnia complaints represent a heterogeneous group. A diagnostic classification system that appropriately and reliably assists in distinguishing or differentiating insomnia subtypes is vital because treatment decisions are largely determined by the eventual insomnia diagnosis assigned. This article reviews the evolution of insomnia classification systems and briefly describes those in current use. Subsequently, these classification systems are evaluated by considering their reliability, validity, and utility in clinical applications. In addition, limitations of the existing insomnia nosologies are discussed, and methods for countering these limitations are considered.