Sleep disturbances in schizophrenia
The sleep of a schizophrenic patient is usually disturbed. The structure of sleep especially changes before exacerbation or in the process of relapse of the disease. According to S. Dencker et al. (1986), sleep disorder can be considered the most sensitive indicator of an incipient exacerbation of psychosis. The first signs of sleep disorder are manifested by frequent awakenings during the night, “restless sleep.”
Sometimes the patient does not sleep for several days, and then there is increased drowsiness, which persists for a fairly long period of time. As they recover from psychosis, the patients’ sleep is gradually normalized, but it is not fully restored either by objective indicators or by subjective data.
To determine the causes of sleep disturbance and increased sleepiness during the day, it is necessary to study the structure of sleep throughout the night (polysomnography).
Many sleep doctors believe that sleep disturbances in schizophrenia are likely nonspecific and, unlike depression, do not require expensive sleep research.
Sleep disturbances are most often recorded in those patients with schizophrenia, whose clinical picture is dominated by anxiety-depressive symptoms.
Especially persistent sleep disorders are observed in patients with a dual diagnosis: schizophrenia and dependence on psychoactive substances.
Winkelman J. (2001) noted cases of quite frequent occurrence of obstructive sleep apnea in schizophrenic patients.
According to some authors, sleep disorder in schizophrenia varies in a wide range, however, most often there are disturbances in falling asleep, changes in the 3rd and 4th phases of sleep, especially the contraction of the 4th phase – deep, slow-wave sleep (“slow wave sleep”), changes in the continuity of sleep, and also the reduction of REM – phases (Monti J., Monti D., 2004). Reduction of the 4 sleep phase is of particular diagnostic value for schizophrenia (Feinberg I. et al., 1969; Poulin J. et al., 2003).
Sleep disturbances in schizophrenia
- Falling asleep
- Sleep disruption
- Sleep phase 4 reductions ( NREM sleep duration, percentage of NREM sleep)
- Dysregulation of REM sleep (decreased REM latency, decreased REM sleep during the night)
- Lack of information processing during sleep
M. Keshavan et al. (1996), proposed to distinguish between variable and invariant sleep parameters in schizophrenia, the former, for example, such as REM sleep parameters (REM – latency and REM density), depended on the mental status of patients, significantly worsening before an exacerbation or during a psychotic episode, on the contrary, the second, in particular, phase 4 , characterizing deep, “slow wave sleep” (duration of slow wave sleep, percentage of slow wave sleep), almost always and regardless of the phase of the disease (prodromal, exacerbation, stabilization, remission) were stably violated in schizophrenia. M. Keshavan et al. (2004) also noted changes in slow-wave sleep in relatives of schizophrenic patients. According to these authors, disturbances in “slow wave sleep” can be an indicator of the danger of developing schizophrenia. It is interesting to note that the proportion of “deep sleep” in young patients shows a negative correlation with the severity of negative symptoms of schizophrenia (Ganguli R., et.al., 1987).
For patients with schizophrenia during the period of exacerbation of the disease, it is quite characteristic to disrupt the continuity of sleep, measured by such indicators as: sleep latency, sleep efficiency, awakening time after the onset of sleep, frequency of awakenings per night, total sleep time. From the point of view of B. Hoyt (2005), the continuity of sleep is determined by the state of the dopaminergic system, and the disturbance of the sleep rhythm, in particular, corresponds to its intensification.
A decrease in REM latency, a decrease in REM sleep density, is especially noticeable during a psychotic episode. Short periods of REM latency are often detected in patients with severe hallucinatory symptoms (Feinberg I. et al., 1965). According to V. Zarcone et.al. (1975), in patients with schizophrenia there is a kind of “selective deprivation of the REM-phase of sleep, i.e. there is a dysregulation of REM sleep, but not a change in its structure.
Sleep studies in schizophrenic patients show that information processing is impaired during sleep . So, in particular, if light and sound stimuli are used during the night and at the same time the evoked potentials are measured, then in patients with schizophrenia, an enhanced resonance of the response in the theta range can be found (Roschke J. et al., 1998).
Usually, patients use small doses of clozapine or other antipsychotics to normalize sleep, sometimes they take sleeping pills and tranquilizers. In studies T. Neylan et al. (1992) found that even after the abolition of antipsychotics sleep changes associated with their exposure, may be fixed on for 6 weeks after their cancellation.
Many researchers associate the directions of further research on somnology in the field of schizophrenia with the use of modern methods of neuroimaging during this period (Gauggel K., 2008).