Sleep Disturbances in Schizophrenia and the Thalamus

human brain toy

Schizophrenia patients have long suffered from disturbed sleep. Manifestations have included sleeping too much, insomnia, disrupted circadian rhythm and symptoms similar to those of sleep apnea. Research has linked these manifestations to reduced quality of life and problems with mental functions such as learning and attention. Now, new research has identified one possible mechanism of sleep problems and how it may relate to a commonly experienced positive symptom: hallucinations.

Sleep and Schizophrenia

Anecdotal self-reports about sleep disturbances in schizophrenics have existed for decades. Patients have complained that they sleep too much, or need frequent daytime naps, or suddenly get drowsy and must sleep immediately (a phenomenon normally associated with sleep apnea). Others have complained of frequent bouts of insomnia and unrestful sleep, sometimes associated with higher levels of positive symptoms, such as hallucinations, delusions and paranoia.

Recent research tends to confirm these anecdotal reports. A Turkish study published in the March 2010 issue of the journal European Psychiatry reported not only significant sleep disturbances among schizophrenics, but reduced quality of life. A larger study, involving 150 schizophrenia outpatients, published in the October 2010 issue of the journal Psychiatry Research, found evidence of disruption in schizophrenics’ circadian rhythm, the biological mechanism responsible for regular nighttime sleep cycles. According to the abstract of the latter study:

“Compared to healthy controls, patients with schizophrenia reported significantly increased sleep latency, time in bed, total sleep time and frequency of naps during weekdays and weekends along with normal sleep efficiency, sleep satisfaction, and feeling of restfulness in the morning. In conclusion, sleep-onset insomnia is a major, enduring disorder in middle-aged, non-hospitalized patients with schizophrenia that are otherwise clinically stable under antipsychotic and adjuvant medications. Noteworthy, these patients do not complain of sleep-maintenance insomnia but report increased sleep propensity and normal sleep satisfaction.”

A currently proposed Australian study is looking into the connection between schizophrenia and narcolepsy.

Schizophrenia, the Thalamus, Sleep and Hallucinations

A study at the University of Wisconsin-Madison in the United States, published in the September 15, 2010 issue of the American Journal of Psychiatry, involved doing electroencephalograms (EEGs) on schizophrenics and healthy controls while they slept. The results revealed a deficit in the sleep brainwaves of the schizophrenic subjects. During all non-dreaming stages of sleep, the brains of schizophrenics did not enjoy normal spikes in brain activity. These spikes are associated with the thalamus, a small part of the midbrain, which humans have in common with cold-blooded life forms such as lizards. The study suggests that the thalamus of schizophrenics may be functioning defectively.

The researchers highlight the possibility that EEGs could someday be used to help diagnose schizophrenia through examination of the brain wave deficit. Another suggestion, however, is that this deficit may be correlated with a symptom experienced by a significant proportion of schizophrenics: hallucinations. The thalamus is partly responsible for filtering information, and hallucinations may arise from improper filtering if the thalamus is defective of malfunctioning.

As is usually the case, the researchers say that this matter needs further study. In this case, they may be correct that the connection between a defective or malfunctioning thalamus and positive symptoms should be further looked into.

References:

Ferrarelli, Fabio et al. Thalamic Dysfunction in Schizophrenia Suggested by Whole-Night Deficits in Slow and Fast Spindles. American Journal of Psychiatry.

Poulin, Julie et al. Sleep Habits in Middle-Aged, Non-Hospitalized Men and Women With Schizophrenia: a Comparison with Healthy Controls. Psychiatry Research.

Roberts, Mary. Sleep Disorders May Have Similar Triggers as Schizophrenia. Staho.com.

Sarkar, Sukanto et al. Slow Wave Sleep Deficits as a Trait Marker in Patients with Schizophrenia. Schizophrenia Research.