Each person spends one third of his or her life asleep. It is not surprising that such a complex and pervasive cognitive state should be affected by drugs in many different ways. A philosophy that remains cogent for the CNS is that new research almost always shows this system to be more complex than previously thought. Only a few years ago, if patients complained of difficulty sleeping, they were given pills, often dangerous and addictive pills, to induce sleep no matter what the basis of the complaint might be. Sleeping pills may be safer now, and the understanding of the sleep state itself has increased rapidly. Diagnoses are still diffuse, however, and treatments are often poorly directed. Depression is the offspring of the phlegmatic disposition and the melancholia of another era. Clinically, diagnosis is based on a global assessment of symptoms. It is likely that a diagnosis of depression may include a spectrum of underlying diseases that cannot now be clinically differentiated.

Medications have multiple effects on sleep and have many side effects. Progress has, however, been made beyond mother's little pills. Insomnia is no longer a diagnosis but a complaint to be addressed—a symptom of 1 of 60 potential sleep disorders. Each of these disorders has specific and appropriate treatments.