Many biological necessities that human take, such as eating foods or interacting with others can vary from one culture to another. Asian people mainly consume rice while western people consume wheat and they both are totally acceptable. Interaction with others is more diverse: Every culture has a unique style of showing their emotions. However, it seems sleeping has a small—perhaps no—difference among many religion, cultures or nations that exist in this world. As sleeping is universal and uniform action of human, its function and roles are crucial to the life of humanity.
It is obvious that without sleeping, humans feel “lower affective well-being,” such as the feeling tired or stressed. On the other hand, people who sleep well have a tendency to show positive well-being state (Wrzus et al, 2014). Then, up to what extent, does sleeping affect our mental health? And how well do people with various mental illnesses sleep compared to the normal people?
Schizophrenia is one of the most well known mental illnesses that current people face. According to the American Psychiatric Association, schizophrenia can be defined as follows: a chronic brain disorder that can include delusion, hallucination, trouble with thinking and concentration (Yao et al, 2000). As schizophrenia is a rising illness on which research began decades ago, there are no medications that can fully recover it. Therefore it is necessary to understand the new illness from various approaches, such as genetics, behavior research or psychological approach.
Then, does a bad sleep quality result in schizophrenia? Or does schizophrenia cause malfunctioning sleep? Background Information about Sleep Disorder and Schizophrenic Symptoms
Unlike depression, schizophrenia is categorized as psychosis, more than neurosis (such as ADHD). This indicates that schizophrenia probably is occurred for many reasons, such as biochemical, physiological and psychological problems. Fortunately, currently, one of the most well-known causes of schizophrenia is the excess secretion of dopamine (Feinberg, 1982). Patients of schizophrenia showed increased numbers of neurotransmitter level, but it is yet to be determined why dopamine has increased. Still, current medical cures that can be given to the patients are dopamine-inhibiting doses. Scientists have found that abnormal secretion and distribution of neurotransmitters, for example, dopamine, serotonin, and glutamate causes a decrease in brain cortex from the brains of patients with schizophrenia. However, this cure can only be effective when the administration has occurred in the early stage of illness. If the duration of untreated psychosis increases, it becomes significantly harder to rehabilitate.
This research will investigate the relationship between the quality of sleep and the symptoms of schizophrenia. However, sleep quality is a complex phenomenon that is difficult to define and measure objectively (Buysse et al, 1988). Daily usage of the word “sleep quality” generally includes qualitative aspects of sleep, such as depth of sleep and how restful the sleep is. Therefore it is necessary to quantify them by using the following variables: sleep duration, sleep latency or number of arousals (Buysse et al, 1988).
Pittsburgh Sleep Quality Index, PSQI, one of the well-known sleep quality indexes, is developed by Buysse in 1988. It assesses the quality of sleep and discriminates “good” sleepers and “poor” sleepers by (Buysse et al, 1988). It consists of 19 questionnaires and each is weighed on 0-3 scales. The measures show a strong correlation with related sleep constructs (Mollayeva et al, 2016).
Discussions about Sleep and Schizophrenia Relationship
In order to investigate how patients with schizophrenia sleep and how they are affected by the sleep they have, this research incorporates many past data.
Sleep disturbances, such as long sleep latency and high total awake time, which destroys the circadian rhythm, are identified to be one of the major contributing factors for the development of psychosis in young people, including schizophrenia (Ruhrmann et al, 2010).
So, do malfunctioning activities of sleep of schizophrenic patients cause the symptoms of schizophrenia, or the opposite causation and result relationship is occurring?
Sleep Disorder and Circadian Rhythm
About 80% of the patients with schizophrenia experience sleep disorder that disrupts their circadian rhythm, yet very little is known about the relationship between sleep and the circadian rhythm (Wulff et al, 2012). Compared to people without schizophrenia who suffer sleep disorder, significant circadian rhythm disruptions occurred in the patients. Out of 20 patients researched, half of them showed misalignment of melatonin cycles and irregular sleep epochs (Wulff et al, 2012).
Also, another research about sleep quality of 321 patients of schizophrenia, precisely patients who were diagnosed as schizophrenia but never received treatment, comparatively showed negative results of sleep compared to 331 healthy subjects (Chouinard et al, 2004). According to the research, the meta-analysis Chouinard and the researchers investigated about the treated patients with schizophrenia had following disorders with comparison to the healthy subjects: Increased sleep latency, decreased total sleep time and decreased sleep efficiency (using sleep efficiency index, SEI). On the other hand, however, only the group that is consisted of untreated patients with schizophrenia showed high total awake time (Chouinard et al, 2004). These results conclude that the symptoms related to sleep quality of schizophrenia patients are not necessarily the consequence of neuroleptic treatments, meaning that the sleep disturbances that the patients' experience are an intrinsic feature of schizophrenia.
Symptoms of Schizophrenia Due to the Absence and Disturbance of Sleep
It is well known by many of past researches that the functions of sleep are stabilization, enhancement, integration, recognition, and processing the recent memories. While memory consists of many different features such as perceptual, verbal and emotional memories, the processes enhance the durability, flexibility, and automation of these memories (Stickgold et al, 2007).
While sleep of healthy people can perform active processing of memories, the schizophrenia patients’ sleep is malfunctioning in terms of memory processing: A group of medicated patients with schizophrenia showed reduced recall of the Rey-Osterrieth Complex Figure, a test of memory, along with reduced sleep latency and efficiency (Goder et al, 2004). Also, Goder found that slow wave activity of sleep positively correlated with both better performances of neuropsychological measures in healthy subjects. In contrast, treated schizophrenia patients, who initially showed reduced slow wave activity, showed relatively few significant correlations with slow wave activity. These results concluded that the absence of sleep for patients with schizophrenia definitely affects the brain function, especially the process of memory. Furthermore, the research suggests that the deficits the patients of schizophrenia experience is due to the deactivation of memory consolidation processes that occurs during sleep rather than the amount, latency or distribution sleep hours (Manoach et al, 2004).
Although past data have been considering poor sleeping quality as the main reason for having the negative symptoms of schizophrenia, the next researches will view the relationship between sleeping and the symptoms from the other side.
Opposite Cases: Symptoms of Schizophrenia That Causes Sleep disorder
Hallucination, one of the symptoms that people with schizophrenia suffer, including both visual and auditory, is considered to be a symptom that affects sleep disorder (Wilson et al, 2012). Patients with psychosis may get little daylight because they tend to keep curtains closed during the day because of a perception of threat from outside and finding general stimulation they receive in the day time may be distressing therefore prefer to be awake in quieter periods (Wilson et al, 2012). Many researchers argue that the effects of medication or deprivation of sleep cause symptoms of schizophrenia. However, there may be a possibility of the opposite relationship, the symptoms of schizophrenia consequently cause sleep deprivation.
From this research, another variable, environment that patients live, can actually manipulate the quality of sleep. Wilson suggests that it is important to take the environment of healthy subjects and schizophrenic patients into account when evaluating sleep and the symptoms of schizophrenia relationship.
Qualitative Category of Sleep Disorder: Nightmares and Schizophrenia
Although nightmare is extremely difficult to quantify, it definitely is one of the important categories that indicate the status of human health. Although the cause of nightmare remains unclear, many past data assume that stress is the main cause among many other causes (Picchinoi et al, 2002).
According to Levin and Raulin in 1991, the word “nightmare” can be defined as “a scary dream that awakens the dreamer from sleep.” Based on the definition, Levin in 1998, conducts research to clarify the relationship between nightmare and schizophrenia. Levin assessed participants with the following categories: physical anhedonia, perceptual aberration, thought disorder, magical ideation, ambivalence, social fear, and somatic symptoms. Also, the participants completed BDI, STAI, and SD, the schizotypy scales to sort themselves to different groups based on the scales (Levin, 1998). Consequently, Levin concluded that frequent nightmare subjects were observed to have a higher possibility of having schizophrenia. Also, the frequent nightmare subjects had a significantly higher measure of trait anxiety (Levin, 1998).
This research indicates that the people with frequent nightmares are associated with “cognitive slippage and perceptual distortion, and consequently may reflect a phenotype of an underlying vulnerability trait for schizotypy” (Levin, 1998).
Another research of the relationship between nightmare and schizophrenia, conducted in 1987 by Hartmann, suggest that frequent nightmare subjects scored higher on Minnesota Multiphasic Personality Inventory test (MMPI) compared to control group of the observation, that rarely encounter nightmares. According to the interview Hartmann conducted, the frequent nightmare sufferers can be explained as “sensitive and showed schizophrenic spectrums but also showed artistic and creative tendencies and interests, in contrast to the other groups” (Hartmann et al, 1987).
This research paper investigated the relationship between quality of sleep and the symptoms of schizophrenia from various perspectives. Although many current researchers have tendency to view malfunctioning sleeping, such as long sleep latency, short sleep duration or absence of REM sleep as causes of the negative symptoms of schizophrenia. However, there are still numerous studies that have found low sleep quality as a consequence of schizophrenic symptoms.
In general, the fact that sleeping and schizophrenia are related in some kind of form is apparent (although it is yet to be known that which one is suitable for cause of the other). Many researchers that consider malfunctioning sleep as the cause of schizophrenia tried to justify that people with low sleep quality have a higher possibility of having schizophrenia. Therefore many experiments of this form investigated the risk of schizophrenia in healthy subjects.
On the other hand, researches that have tried to view sleep malfunctioning as symptoms of schizophrenia actively investigated patients with schizophrenia and their environment. Through these researches, sleeping disorders of schizophrenia were known to be influenced by the environment that the patients were in, such as the irregular rhythm of life pattern (circadian rhythm disruptions), which eventually damages the quality of sleep.
Conclusion and Discussion of limitations
The main goal for this research is to view the relationship between sleep quality and schizophrenia from various perspectives and determine which one serves as a cause for the other. Initially, this research predicted that sleep disorder causes schizophrenia rather than schizophrenia causing sleep disorder. To conclude, this cannot be determined, but it is evident that two-variable relationship is very weak to justify: there are many variables such as environment and nightmares, which need to be considered when discussing sleep and schizophrenia. Also, this research fails to investigate the variables as quantitative variables as sleeping and symptoms of schizophrenia are very subjective and can appear in various forms. Especially, a nightmare is hardly observable, and the researches that are related to nightmare only sort levels of nightmares in subjective forms. This absence of definite nightmare measures (and any other qualitative sleeping categories, especially dreams) makes very hard to compare and contrast to other researches.
Overall, it is evident that low sleep quality can lead to schizophrenia, but its specific measures and numbers remain unknown. (1952 words)
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