The lifetime prevalence of schizophrenia is estimated to be between 0.5% and 1%, with an incidence rate of approximately 1 per 10,000 per year (1). The male to female ratio is roughly equal. Women are more likely to have a later onset, more prominent mood symptoms, and better overall prognosis (2).

Most patients with schizophrenia have a prodromal phase, consisting of the gradual development of a variety of symptoms, including social withdrawal, deterioration in hygiene, loss of interest in work or school, and/or irritability. Subsequently, delusions, hallucinations, and grossly disorganized behavior typically mark the point at which individuals are diagnosed with schizophrenia. The onset of schizophrenia usually occurs between the late teens and the mid-30s, although it can begin much later (2). The age of onset has pathophysiologic and prognostic implications, with earlier onset being associated with worse premorbid functioning, male gender, lower educational achievement, more structural brain abnormalities, more cognitive impairment, and a worse overall outcome. Conversely, late-onset cases are typically associated with a higher percentage of women and better premorbid functioning (2).

The course of schizophrenia is highly variable, although complete remission is rare. Some patients are relatively stable while others have frequent acute psychotic exacerbations. A few patients require long-term institutionalization (2).

The diagnosis of schizophrenia requires the presence of two or more of the following characteristic symptoms, each present for a significant portion of time during a 1-month period (2): delusions, hallucinations, disorganized speech, grossly disorganized or catatonic behavior, and negative symptoms such as flat affect. If delusions are bizarre or hallucinations consist of either two or more voices conversing with each other or a voice keeping up a running commentary on the patient’s thought or behavior, only one symptom is required for the diagnosis. Schizophrenia is associated with significant social dysfunction.

Insomnia is a common symptom in schizophrenia. Sleep maintenance or sleep-onset insomnia is the most common sleep complaint in acute psychotic episodes associated with schizophrenia (3). Severe insomnia often appears as a prodromal manifestation of acute psychotic decompensation. Nightmares and terrifying hypnagogic hallucinations are also common. Circadian disturbances frequently arise in patients with schizophrenia, in part secondary to loss of social zeitgebers. Substance abuse is rampant in this patient population and complicates comorbid sleep disorders.