Insomnia related to another mental disorder should be diagnosed when a patient has a predominant complaint of insomnia for at least 1 month that causes daytime symptoms and impaired functioning. The insomnia is judged to be related to a coexistent Axis I or II disorder, but the sleep complaint constitutes a distinct focus of treatment or patient concern. In many cases, patients will present primarily with a complaint of insomnia, and only on further questioning will they reveal symptoms of a mental disorder. This diagnosis should not be used if a patient has a concurrent medical or substance use disorder that might explain the symptoms.

The most common psychiatric disorders that present with prominent insomnia are mood disorders (including major depressive episode, dysthymic disorder, and manic episode), anxiety disorders (including generalized anxiety disorder and panic disorder), and psychotic disorders, predominantly schizophrenia. Patients with Axis II disorders such as borderline personality disorder and histrionic personality disorder often complain of chronic insomnia as well.

Behavioral/psychotherapeutic treatment Several behavioral interventions, either alone or in combination with pharmacotherapy, can benefit psychiatric patients with insomnia. For example, a clinical replication series with 100 outpatient insomniac patients showed that the degree of sleep pattern changes produced by a cognitive-behavioral intervention was similar in patients with psychophysiological, drug-dependent, or psychiatric insomnia (Morin et al. 1994b). Patients whose insomnia was associated with psychiatric disorders (mostly affective and anxiety disorders) had more severe sleep disturbances at baseline and did not achieve the same sleep patterns at posttreatment as either of the other two subgroups. However, there was little difference in the absolute levels of changes obtained on the various outcome measures, suggesting that even those patients with secondary insomnia benefited from the sleep-focused intervention.

In another clinical case series (Dashevsky and Kramer 1998) of 48 patients with comorbid psychiatric disorders (including 28 with depression), a short-term behavioral treatment for insomnia (six sessions over a 2-month period) produced moderate to clinically important improvements in 56% of the patients at the short-term follow-up. Improvements were noted for both sleep parameters and daytime functioning (e.g., fatigue, mood, social discomfort). Additional pilot studies have also examined the effect of behavioral interventions on the sleep of inpatient populations. In a naturalistic study (Edinger et al. 1989b) conducted on three psychiatric wards, elimination of daytime napping and strict enforcement of a regular arising time produced slight but consistent improvements in sleep initiation, continuity, and duration. In another study (Edelstein et al. 1984), reductions of caffeine intake among 10 psychiatric inpatients with sleep maintenance insomnia reduced the number of night wakings and the number of requests for hypnotic medications. Twenty psychiatric patients with secondary insomnia were treated on an inpatient basis with a combination of psychotherapy, behavioral therapy, and pharmacotherapy (Tan et al. 1987). After an average hospitalization of 38 days, 16 of the 20 patients were clinically improved on a subjective index of sleep quality. Finally, an innovative study by Holmes and colleagues (1995) evaluated a sleep management program specifically designed for patients with severe mental illness. First, they defined the content of the sleep management training module based on specific concerns of 23 patients with severe mental illness who also had sleep-related problems (education, sleep environment, sleep behaviors, and medications/drugs). Then, they pilot tested the training module with a second cohort of 18 participants (44% with a diagnosis of schizophrenia, 22% with major depression). The findings showed that patients increased both their knowledge of sleep management skills and their subjective ratings of sleep quality.

Pharmacological treatment Pharmacological treatment should be targeted at the underlying disorder, and not only the insomnia symptoms. As the psychiatric disorder improves, insomnia is also likely to improve. Few clinical studies have specifically addressed insomnia related to specific mental disorders. However, almost all treatment trials of pharmacotherapy for depression, anxiety disorders, and psychotic disorders include sleep symptoms as outcome measures in assessment instruments. Sleep symptoms usually improve at about the same rate as other symptoms of the disorder, but depending on the specific medications involved, sleep symptoms may actually improve more rapidly than other symptoms. For instance, sedating antidepressants or antipsychotic drugs can produce almost immediate improvement in sleep symptoms, whereas more “alerting” drugs may take longer to improve sleep (Kallepalli et al. 1997). Conversely, treatment of insomnia can be associated with improved psychiatric symptoms. For instance, Post et al. (1991) treated insomnia in patients who also met criteria for generalized anxiety disorder with estazolam in a single bedtime dose. Sleep quality improved as expected, but daytime anxiety also decreased.

Several specific treatment approaches may be appropriate for patients who complain of insomnia during the course of major depressive disorder. The approaches include use of 1) a single antidepressant, 2) combinations of two different antidepressants, and 3) an antidepressant with an adjunctive benzodiazepine agonist. Treatment with a single antidepressant is often effective. Among the new antidepressant drugs, more sedating agents such as nefazodone lead to larger improvements in insomnia and in polysomnographic sleep quality compared with more “alerting” drugs such as fluoxetine (Rush et al. 1998). However, even fluoxetine was associated with significant improvements in subjective sleep quality in this study. TCAs such as nortriptyline can also relieve insomnia and improve laboratory sleep measures (Buysse et al. 1996). However, for some patients, treatment with a single antidepressant will not be sufficient to alleviate insomnia complaints. One drug utilization review indicated that approximately 20% of the patients taking SSRIs were also prescribed an anxiolytic/hypnotic or trazodone (Rascati 1995). In such cases, the use of an SSRI antidepressant with low-dose (25-100 mg) trazodone or sedating TCAs (doxepin, amitriptyline, trimipramine) can be an effective combination (Jacobsen 1990; Nierenberg et al. 1994). There is a small risk of “serotonin syndrome” with combined trazodone and SSRIs (Metz and Shader 1990). Controlled treatment trials have confirmed that use of an SSRI or another antidepressant with an adjunctive benzodiazepine receptor agonist is effective without delaying the antidepressant effect or diminishing its magnitude (Buysse et al. 1997a; Nolen et al. 1993; Rickels et al. 1998).

Among patients with schizophrenia, treatment with traditional antipsychotic drugs, including haloperidol, is associated with improved sleep continuity, increased REM sleep, and variable effects on slow-wave sleep (Keshavan et al. 1996; Maixner et al. 1997). More sedating older agents, such as chlorpromazine, thioridazine, and loxapine, may be helpful for insomnia, but side effects such as anticholinergic effects and hypotension limit their use. For patients who have prominent sleep complaints, relatively sedating agents from the newer antipsychotic classes, such as olanzapine, quetiapine, and clozapine, are often appropriate choices. Clozapine has been shown to improve sleep continuity and increase REM activity, with variable effects on slow-wave sleep (Hinze-Selch et al. 1997; Wetter et al. 1996). Adjunctive benzodiazepines may also be useful in the management of insomnia in psychosis.

For patients with anxiety disorders, the clinician may “load” relatively more of a benzodiazepine sedating or antidepressant dose in the evening hours before sleep. Concurrent treatment with an SSRI and a benzodiazepine receptor agonist or trazodone, as in depression, also may be effective. Panic attacks occurring during sleep respond to bedtime doses of imipramine or benzodiazepines (Mellman and Uhde 1990). The nightmares and night terrors occurring with PTSD improve to about the same degree as insomnia and other symptoms during treatment with various medications, including TCAs, MAOIs, and benzodiazepines (van der Kolk 1987).