INTRODUCTION
The main challenges of the modern world—globalization and integration—have provided a significant impetus for development in all scientific spheres, greatly improving humanity’s life globally. However, they have also become a burden for the psycho-physical well-being of individuals due to accelerated communication and increased competition. Given these challenges, it is important to study and implement all possible tools to support the physical and mental health of individuals. One such tool is quality sleep, which serves as an effective, safe, and accessible natural means of restoring physical and emotional resources [1,2]. The primary difficulties hindering the use of sleep for enhancing public and individual health include patients disregarding sleep problems, postponing their resolution with specialists, and insufficient awareness regarding the appropriate professionals to consult. The first and most crucial link in addressing these issues is the general practitioner who can identify the problem and promptly refer the patient to a sleep specialist or, in the absence of such a specialist, independently determine the preliminary cause of reduced sleep quality and direct the patient to the necessary specialist (psychotherapist, psychiatrist, neurologist, endocrinologist). Therefore, the effectiveness of the treatment outcome for patients depends on the level of preparation and expertise of the general practitioner in understanding the relationship between sleep quality and physiological and psycho-emotional processes in the body.
The study conducted by Sybirna [3] focused on the significance of sleep in ensuring mental health. The researcher presented global statistics on sleep problems, and identified and analyzed the most common types of sleep disorders (insomnia, hypersomnia, parasomnia, narcolepsy, and sleep-wake cycle disorders). The author also outlined the essential components of quality sleep and provided recommendations for beneficial habits to enhance sleep quality. The work of Buriakovska and Isayeva [4] explored the connection between sleep disorders and the development and course of cardiovascular diseases. The authors identified shared pathogenesis mechanisms between hypertension, type 2 diabetes, and sleep disturbances. They highlighted factors such as eating behavior disorders (overeating), increased anxiety levels, and depression as crucial contributors to the development of both these diseases and sleep disorders. Consequently, sleep disorders can act as both a factor in the development of hypertension and diabetes and a symptom accompanying them. Romanenko and Tretyak [5] investigated sleep disturbances as a factor in metabolic changes in obesity, insulin resistance, and type 2 diabetes. Their review of scientific sources demonstrated that sleep disturbances influence the development of diseases caused by metabolic disorders, as they provoke worsened glycaemic control, increased levels of glycated hemoglobin, decreased leptin levels, and increased ghrelin levels.
Considering the impact of sleep quality on mental and physical health, research is ongoing in the areas of diagnosis and treatment of sleep disorders. Mazur et al. [6] proposed the use of questionnaires as the primary diagnostic tool for sleep disorders. The study results indicated that the use of several questionnaires (Pittsburgh Sleep Quality Index, Insomnia Severity Index, Bergen Insomnia Scale, Sleep State Indicator) allows for the detection and evaluation of insomnia severity, recommending their application as an effective method for diagnosing sleep disorders. Kopchak et al. [7] conducted a study to determine the effectiveness of therapy for anxiety-related sleep disorders in patients with multiple sclerosis. The clinical trial of the applied medication (based on crezacin and melatonin) demonstrated efficacy in normalizing sleep, reducing anxiety levels, and alleviating asthenia.
Analyzing the results of each study, it can be noted that they examined specific aspects of sleep as the research object, but the comprehensive exploration of its relationship with the body’s condition was not conducted. Therefore, the purpose of this study was to conduct a literature review to establish the correlation between sleep quality and the physical and mental health of individuals, as well as to determine the most effective current method of psychotherapy for sleep disorders.
MATERIALS AND METHODS
To study the importance of quality sleep and its correlation with physical and mental health, theoretical methods such as analysis, synthesis, comparison, and generalization were chosen. The selection of these methods was justified by the complexity of the research object and the need to structure its elements.
The analysis method was used to obtain necessary data about the research object and applied to: define the quality of sleep and its parameters, types of sleep disorders, the correlation between sleep and physical and psychological health, and methods and directions of psychotherapy in treating sleep disorders. The analysis was conducted using thematic scientific sources from PubMed, MEDLINE, and Google Scholar databases. The data search for analyzing the concept of sleep quality and its relevant parameters was conducted with the following query: “sleep quality,” “sleep duration,” “norms of sleep duration,” “sleep continuity,” “deep sleep,” “sleep phases,” and “duration of deep sleep.” Five sources matching the query were selected for analysis. Materials for analyzing the types of sleep disorders were selected using keywords such as: “types of sleep disorders,” “main directions of sleep disorders in somnology,” “insomnia,” “hypersomnia,” “parasomnia,” “somnambulism,” “sleep paralysis,” “sleep-related breathing disorders,” and “movement disorders during sleep.” A total of 18 scientific publications were processed.
The search for data analysis on the correlation between sleep and physical health was conducted using the following keywords: “impact of sleep on physiological processes of the body,” “physiological dysfunctions leading to sleep disorders,” “relationship between sleep and metabolic processes,” and “impact of sleep on the body’s defense and regulatory activity.” The search focused on theoretical and clinical studies. The analysis of clinical study results on the correlation between sleep quality and physical health was used as an example to support the obtained theoretical information. Two relevant sources were selected for this direction. Information search in scientific publications for analyzing the correlation between sleep and mental health was conducted using the following keywords: “impact of sleep on mental health,” “impact of sleep on psychological processes,” “mental disorders affecting sleep quality,” “impact of sleep quality on the development of mental disorders.” A total of 6 publications of theoretical and clinical studies were selected for processing. The formation of the query for data analysis regarding psychotherapy approaches in treating sleep disorders was done using keywords: “methods of psychotherapy for sleep disorders.” Seven scientific publications were selected for processing. Overall, 52 scientific sources from 2001 to 2023 were selected for analysis (Supplementary Fig. 1 in the online-only Data Supplement).
The synthesis of the obtained data was used to investigate the psychological aspect of the importance of quality sleep and its influence on the fundamental manifestations of an individual’s psyche–processes, states, and traits. The comparison method was applied during the review of psychotherapy methods for sleep disorders.
Generalizing the collected data about the research object allowed identifying the most effective approaches in dealing with sleep disorders through psychotherapy and discovering promising directions that allow utilizing sleep in the treatment of certain mental and psychological disorders. Ethical approval for this study was granted by the Ethics Committee of Kyiv International University, approval number 124-BN.
MAIN INDICATORS OF SLEEP QUALITY, FACTORS INFLUENCING THEM, AND TYPES OF SLEEP DISORDERS
To find out the nature of the relationship between sleep and physical and mental health, it is necessary to outline the main indicators of sleep quality. The simplest method for evaluating sleep quality is an individual’s feelings upon awakening. Alertness, energy levels, and reduced tension indicate that sleep has fulfilled its function of restoring physical and emotional resources depleted during periods of activity. Objectively, sleep quality is determined by three main indicators: duration, continuity, and depth. Sleep duration depends on individual needs and changes with age. The recommended duration for children under 12 months is 16 hours per day, from 1 to 3 years is 13 hours, from 3 to 5 years is 12 hours, from 5 to 10 years is 11 hours, from 10 to 12 years is 10 hours, starting from 17 years is 8 hours, and for adults, it is no less than 7 hours. The presence of pathological processes and chronic illnesses usually affects the need for increased sleep duration [8,9].
Continuity is a characteristic of the uninterrupted and gradual transition between sleep phases. A full sleep cycle includes rapid eye movement (REM) and non-rapid eye movement (NREM) phases, which automatically alternate, changing one another. In the REM phase, body relaxation occurs while the brain remains active, resulting in realistic and vivid dreams. If awakening does not occur within 20 minutes during this phase, the REM phase transitions to slow-wave sleep, which is divided into four sub-phases. During the first and second sub-phases (light sleep and transition), physiological activity decreases (body temperature, heart rate, and brain activity slow down), and consciousness is completely disconnected [10]. The third and fourth phases of deep and maximal deep sleep are crucial for physical and emotional recovery, as during this time, the body, freed from primary activity, focuses on life-sustaining processes such as collagen production, increased growth hormone concentration (hence, the longer duration of children’s sleep compared to adults), relaxation of all body muscles (except for eye muscles), and preservation and sorting of acquired information. Usually, dreams are absent during deep and maximal deep sleep phases [11].
The depth of sleep depends on the duration of the deep and maximal deep sleep phases, as this period involves the reloading and restoration of the body’s resources. In normal circumstances, deep sleep should last about 70%, and maximal deep sleep about 25% of the total sleep time [12]. Deviation from these norms in any indicator indicates a decrease in sleep quality and may lead to sleep disorders. The factors influencing the quality of sleep are divided into internal and external. Internal factors include pain, stress, and deterioration of physical and mental health. External factors include the presence of irritants (bright light, loud sounds), disruptions in sleep patterns (work, study, entertainment during night-time), changes in sleep conditions (change of residence, changes in time zones), the consumption of stimulants of the nervous system shortly before sleep (caffeine, alcohol, certain medications), and overeating. Prolonged exposure to these factors can lead to sleep disorders, including insomnia, hypersomnia, parasomnia, sleep-disordered breathing, and sleep-related movement disorders [13].
Insomnia (sleeplessness) is a clinical condition associated with difficulties falling asleep, limited duration, and sleep deprivation. Prolonged insomnia adversely affects both physical and mental health, often accompanied by irritability, constant fatigue, and impaired concentration. Its causes include hyperarousal influenced by physiological, genetic, ecological, and behavioral factors [14].
Hypersomnia (excessive sleepiness) is a disorder related to the body’s inability to restore its resources during sleep. It manifests as increased night-time sleep duration, excessive daytime sleepiness, and sudden falling asleep regardless of the current location. Symptoms accompanying this disorder are similar to those of insomnia (weakness, chronic fatigue, decreased performance, sluggishness), but they have different causes. Hypersomnic syndromes include idiopathic hypersomnia, post-traumatic hypersomnia, infectious hypersomnia, narcolepsy, insufficient sleep syndrome, medication and toxin-induced sleepiness, hypersomnia associated with psychiatric, neurological, metabolic, endocrine disorders, as well as sleep-related breathing and limb movement disorders [15,16].
Sleep-related behaviors and disturbances during falling asleep and awakening, known as parasomnia, include sleepwalking, sleep talking, sleep paralysis, and nightmare disorder [17]. Sleepwalking is a sleep disorder characterized by complex behavioral manifestations such as active movements in bed, walking during sleep, or other manifestations of activity (e.g., sexsomnia). It is more common in children than in adults, and may decrease with age. Sleepwalking occurs during the deep sleep phase, affecting the difficulty of awakening and increasing the risk of self-injury or injury to others. The main causes of sleepwalking are heredity, nervous and mental disorders [18,19]. Talking in one’s sleep, or somniloquy, is not considered a serious sleep disorder as it does not significantly affect its quality. Treatment is only conducted in cases of increased frequency of episodes causing inconvenience to the patient and others. Therapy is primarily aimed at eliminating its causes, which are often stress, post-traumatic stress disorders, depression, or alcohol consumption [20].
Sleep paralysis is associated with a disturbance in the REM phase of sleep. It is more commonly observed during awakening than during the process of falling asleep. Complete muscle relaxation restricts a person’s movements while the brain remains active, leading to dream experiences that appear highly realistic and often are perceived as frightening visions. Sleep paralysis is classified into isolated sleep paralysis and recurrent isolated sleep paralysis [21]. Nightmare disorder, like sleep paralysis, belongs to REM sleep parasomnias. It develops during the deep and maximal deep sleep phases when dreams are absent, distinguishing it from ordinary unpleasant dreams. The mechanism of nightmare disorder is associated with hyperarousal, disruption of fear extinction, and activity in the brain region involved in emotion regulation. Its most common causes are psychological and post-traumatic stress disorders [22].
The most common manifestations of sleep-disordered breathing are apnea, snoring, and catathrenia. Apnea involves a temporary cessation of breathing during sleep. Central sleep apnea occurs due to reduced activity of the brain’s respiratory center and disruptions in the nerve impulses’ connection to respiratory muscles. Obstructive sleep apnea is caused by numerous episodes of upper airway obstruction [23,24]. Snoring during sleep results from the restricted airflow through the respiratory passages, creating turbulence that causes vibration of the tissues in the nose and throat, producing characteristic sounds [25]. In most cases, snoring is accompanied by the presence of apnea. Catathrenia (night-time groaning) is a breathing disorder characterized by monotonous groaning during exhalation, triggered by breathing cessation due to apnoea. The sound is produced by the vibrating vocal cords during the difficult passage of air through their cavities. The difference between catathrenia and snoring lies in the fact that snoring occurs only during inhalation, while night-time groaning occurs during exhalation [26].
Sleep-related movement disorders include restless legs syndrome, periodic limb movement disorder, nocturnal leg cramps, and bruxism. Restless legs syndrome is a sleep disorder caused by the sensation of sharp or burning pain in the legs or painful muscle tension, leading to the patient’s constant desire for leg movements. While the disorder is usually idiopathic, it can sometimes occur as a symptom of vitamin and mineral deficiencies, common in many pregnant women, disruptions in specific metabolic processes, autoimmune diseases, circulatory system disorders, and nervous system disorders [27]. Involuntary rhythmic limb movements, known as periodic limb movement disorder during sleep, usually have the same causes as restless legs syndrome, but sporadically such movements can occur with the patient’s arms [28]. Leg cramps during sleep occur with sudden contraction or stretching of the muscles, often caused by physical overload, dehydration, or severe fatigue. However, they can be a manifestation of more serious body disorders, including those contributing to restless legs syndrome [29]. Bruxism is a syndrome caused by involuntary muscle contractions of the jaw, leading to teeth grinding or clenching during sleep. Its main causes include neurological, psychological, and dental disorders [30].
The quality of sleep is closely related to physical and mental health. Prolonged, uninterrupted, and deep sleep allows the body to rest, restore expended resources, and alleviate physical and psycho-emotional tension. Simultaneously, the absence of significant health problems ensures sound and healthy sleep without interruptions. Therefore, a reduction in sleep quality can serve as a factor for physical or mental disorders and an indicator of their presence in the body.
THE RELATIONSHIP BETWEEN THE QUALITY OF SLEEP AND PHYSICAL AND MENTAL HEALTH, DETERMINING THE EFFECTIVENESS OF THE MAIN METHODS OF PSYCHOTHERAPY FOR SLEEP DISORDERS
The impact of sleep quality on physical health is manifested through changes in the characteristics of physiological processes. Insomnia and hypersomnia inhibit the motor, support, transport, regulatory, and protective functions of the body, affecting the slowdown of metabolism. Sleepwalking and narcolepsy can pose a threat of injury to the patient and, in the worst cases, lead to death (for example, falling from a height while sleepwalking or suddenly falling asleep during narcolepsy) [31]. The mechanism of physiological dysfunction’s impact on the deterioration of sleep quality lies in the disruption of the cyclic process of phase changes due to hyperarousal provoked by the nervous system sending specific signals (insomnia, sleepiness); creating obstacles to the airflow during sleep (apnoea, snoring, catathrenia); disruption of motor function regulation (restless legs syndrome, periodic limb movement disorder); and disturbance of muscle contraction control (leg cramps during sleep, bruxism).
It is worth noting that the lifestyle of an individual significantly influences sleep quality–the level of activity, the presence, or absence of harmful habits, the regimen, and manner of nutrition, and the type of activity. Many clinical studies have been conducted to confirm this. For instance, Sullivan Bisson et al. [32] experimentally examined the connection between physical activity and sleep quality. The study involved 59 healthy adult participants with an average age of 49.43 years. Walking was chosen as the physical activity. Over four weeks, the participants increased the number of daily steps, and the quality and duration of sleep were assessed. The results were compared by analyzing the quality and duration of sleep before and after daily and four-week increases in physical activity. It was found that physical activity positively influenced sleep quality, but did not change its duration. When comparing results by gender, more positive outcomes were found in women. Analyzing the results obtained by scientists, it can be noted that they confirm the previously established thesis about the beneficial effects of moderate physical activity on sleep quality. It is essential to note that the sleep duration did not change with increased physical activity. This is explained by the fact that the level of physical activity did not exceed the permissible value and did not exhaust the participants, who were selected from sufficiently healthy individuals capable of walking quickly and working a full day. The slight difference in sleep quality improvement between men and women may be related to their different perceptions of the same level of physical activity.
Quality sleep and an individual’s psychological health are interdependent and mutually regulating processes. The presence of mental illnesses, psychological disorders, and a general decrease in the level of psychological well-being worsen sleep quality, negatively affecting all manifestations of the psyche (processes, states, and properties). Insomnia and hypersomnia affect cognitive processes, reducing attention, slowing down thinking and perception, impairing memory, and impoverishing imagination; emotional processes, dulling emotions and feelings; and volitional processes, suppressing willpower [33-35]. Chronic manifestations of these disorders are characterized by constant mood deterioration, which can lead to a state of stress and even affect. In addition to the listed consequences, disorders such as apnoea, snoring, catathrenia, bruxism, restless legs syndrome, and periodic limb movement disorder can provoke feelings of shame, lack of confidence, and a decrease in self-social evaluation, which, in extreme cases, can lead to a state of frustration [36]. Sleepwalking, nightmare disorder, and recurrent isolated sleep paralysis can also evoke feelings of fear, the level of which depends on the frequency and intensity of episodes of these disorders.
Each of the mentioned disorders, when acquiring a chronic nature, generally affects the main properties of psychic manifestations, sharpening the negative manifestations of temperament and character and, through the suppression of cognitive processes, worsening the natural abilities of the individual [37]. In the worst cases, prolonged restriction or complete loss of sleep can trigger obsessive thoughts of suicide. The reduction in sleep quality and sleep disorders can act as factors in the development or exacerbation of mental illnesses and disorders, the main ones of which are: anxiety and bipolar disorders, depression, psychosis, paranoia, delirium syndrome, schizophrenia, post-traumatic stress disorder, phobias, disorders related to addictions, obsessive-compulsive disorders. At the same time, considering the interdependence of processes, these disorders can themselves contribute to certain sleep disorders.
Freeman et al. [38] practically confirmed the impact of sleep on mental health by conducting one of the largest randomized controlled studies with a mediation analysis. It lasted for ten weeks, involving 3755 participants who were divided into two groups. One group received digital cognitive-behavioral therapy (CBT) to address insomnia issues, while the other underwent general clinical care. The effectiveness of the methods was assessed based on insomnia, paranoia, and hallucinatory experiences. The study revealed that the application of digital CBT aimed at improving sleep quality was significantly more effective in reducing insomnia, paranoia, and hallucinations compared to general clinical care. The research results clearly emphasize the connection between sleep quality and mental disorders (in this case, paranoia, and delirium syndrome), as therapy targeting insomnia effectively reduced the manifestations of these disorders.
Currently, there are two main approaches to addressing sleep disorders worldwide: 1) pharmacological therapy, which involves the use of benzodiazepine drugs, agonists of benzodiazepine receptors and melatonin receptors, antidepressants, antipsychotics, antihistamines, and phytotherapeutic agents; and 2) psychotherapy. The advantages of pharmacological treatment include its rapid action, as it is aimed at reducing hyperarousal. However, its drawback is that this therapy does not address the root cause of sleep disorders, and the use of some drugs may lead to side effects such as tolerance and dependence. Recognized psychotherapeutic approaches work gradually but provide convincing and long-lasting results. The working group of the European Sleep Research Society has identified the following psychotherapeutic methods for sleep disorders: CBT, psychological education/sleep hygiene, relaxation therapy, behavioral strategies, cognitive therapy, mindfulness techniques, and hypnotherapy [39]. The mechanisms of therapeutic impact of these methods are outlined in Table 1.
Comparing the mechanisms of therapeutic impact of the main psychotherapeutic methods for sleep disorders, it can be noted that CBT is the most effective, as it allows for a harmonious combination of tools and approaches from other mentioned methods. To support this conclusion, there is a substantial body of clinical research showing positive results of the influence of CBT on sleep quality and the overall psycho-emotional state of patients [40-43]. A notable advantage of this psychotherapeutic method is the absence of side effects when applied. The use of hypnotherapy also demonstrates high effectiveness and the absence of side effects [44]. An additional advantage of this method is the possibility of cultivating self-hypnosis skills in patients. However, a drawback exists, as hypnotherapy may be limited in its application for patients who are not susceptible to hypnosis or approach it with distrust or fear. Hypnotherapy is not recommended in several guidelines for the treatment of insomnia. Despite some anecdotal evidence and individual success stories, clinical guidelines emphasize the lack of substantial scientific evidence supporting its efficacy. Major health organizations and professional bodies prioritize treatments with a strong evidence base, such as CBT, which has consistently demonstrated effectiveness in improving sleep quality and managing sleep disorders. Therefore, while hypnotherapy may be appealing to some, it is not endorsed by leading guidelines as a reliable treatment for insomnia [44].
Currently, there is insufficient information regarding the effectiveness of mindfulness techniques in improving sleep quality. However, there is data on the effectiveness of mobile applications created based on mindfulness principles combined with meditation [45]. Considering the data obtained during the research, it can be summarized that sleep is a maximally comfortable cyclical process aimed at reducing physical and mental activity to ensure rest and the restoration of expended resources. Its quality has a significant impact on all physiological and psychological processes in the human body, and its deterioration serves as an indicator of certain disruptions in physical and mental health.
SLEEP AND MIND: DREAMS, PSYCHOANALYSIS, SLEEP PARALYSIS, LUCID DREAMING, AND CANNABIS EFFECTS
Despite the comprehensive study and research of sleep as a physiological process, some aspects of its psychological dimension remain unresolved. One such aspect concerns the nature and content of dreams. From a scientific standpoint, their functions are not definitively understood, but protective, adaptive, and memory-forming functions that contribute to long-term memory and information processing are considered the most plausible. The impact of dreams primarily extends to the emotional processes of the psyche, more keenly felt by sensitive individuals. Vivid and realistic dreams can elevate anxiety levels, leading individuals to seek meaning in their occurrence as a way to reduce anxiety. On this basis, a psychotherapeutic direction has emerged and continues to evolve—psychoanalysis, initiated by S. Freud’s work “The Interpretation of Dreams” and further developed by the research of C. Jung [46].
A detailed systematic review conducted by Blazhina [47] explored the significance of dream interpretation in the analytical process. The main theses of the study were as follows: the representation of dreams as real and repressed desires is crucial to conduct based on the emotional component of the dream, as it may reveal traumatic experiences; the use of free association method, combined with a focus on the manifest content of dreams, can decode their hidden meaning; psychoanalytic sessions are reflected in patients’ dreams alongside other images perceived by consciousness during its activity. Through a clear and systematic analysis of existing information on approaches to dream interpretation for use in psychotherapy, the researcher identified the most effective and promising psychoanalytic methods. Thus, it is worth agreeing with the author’s conclusions, considering that the study also somewhat relates to sleep quality and its impact on mental health.
Despite the effectiveness of psychoanalysis in addressing many psychological issues, not all therapists and psychoanalysts take it seriously. Leonard and Dawson [48] investigated the marginalization of dreams in clinical psychological practice. The authors noted that the devaluation of dreams and their displacement to the periphery of clinical psychology led to a problem of therapists’ limited or absent responsiveness to patients’ dream-related inquiries. According to the research, the marginalization of dreams is influenced by cultural-historical factors and the political and economic context affecting the development of psychology. By choosing to align itself with natural sciences based on evidence and the ability to empirically measure results, psychology attempts to distance itself from psychoanalysis, viewing dreams as objects lacking clinical and therapeutic value. However, the assertion that working with dreams can yield results with prolonged therapy and appropriate training of the therapist is not refuted. Summing up the study, the researchers emphasized the importance of using dream imagery for effective psychological assistance. Fully agreeing with the authors’ conclusions, it is worth adding that neglecting the analysis of dream content in patients can lead to a decrease in trust in the therapist and, consequently, affect the overall outcome of psychotherapy. On the level of scientific knowledge, it may lead to the neglect of an important and promising direction in psychology.
Supporting the claim about the importance of dream content and the emotions they evoke are the results of numerous clinical studies. Based on a survey of 94 adult participants, Barnes et al. [49] analyzed the process of transferring emotional experiences induced by dreams to the work of employees. According to the survey results, stress manifestations during the working period were associated with the negative impact of reflections arising from unpleasant dreams. The influence of sleep duration and quality on stress occurrence was excluded, as their indicators remained unchanged throughout the survey period. Stress was also noted to cause difficulties at work, and further reflections on them influenced negative pre-sleep thoughts, leading to the repetition of unpleasant dreams, thus potentially creating a cyclical process. Supporting the authors’ conclusions about the significant role of dreams as stress factors, it can be noted that without necessary self-control, support from the environment, or psychological assistance from professionals, persistent exposure to such a state can lead to stress or other mental disorders and illnesses.
Conducting this study, it was noted that sleep paralysis, especially its recurring form, alongside somnambulism and nightmare disorder, can influence a person’s psycho-emotional state, evoking feelings of fear. In this context, attention should be drawn to the research by Kliková et al. [50], aimed at exploring whether sleep paralysis can be pleasant. To obtain results, the authors processed surveys from 172 patients with recurrent sleep paralysis, containing responses regarding episodes of this disorder, trauma symptoms, life satisfaction, and personal characteristics. The study revealed pleasant sleep paralysis in 23% of participants, who described episodes of sleep paralysis as pleasant moments with some elements of fear. Hallucinations were associated with a sense of specific pleasure from illusory body movements, and several patients reported the ability to induce such hallucinations independently. Although the obtained results contradicted researchers’ expectations, upon analysis, they suggested that participants’ perception of sleep paralysis episodes as pleasant experiences could be explained by their ability for lucid dreaming or a level of openness to new experiences. One can agree with the researchers’ assumptions and recommend additional examinations of participants who perceived sensations from sleep paralysis episodes as pleasant to determine the reasons for this abnormal reaction, which may indicate both a high level of cognitive activity and disturbances in psychological defense mechanisms or a tendency to altered states of consciousness.
Many scientists studying sleep investigate the influence of certain substances on its quality. In their work, Edwards and Filbey [51] examined the connection between sleep and cannabis use. The authors’ literature review led to ambiguous conclusions regarding the nature of the influence of cannabis-based substances on sleep. Positive effects included the elimination of sleep onset delay, while negative effects involved shortened sleep duration and reduced fluctuations during the REM phase. Overall, considering the results of most analyzed studies, it was established that cannabis negatively affects sleep quality by altering circadian rhythms. However, most of the conducted studies assessing this impact used a subjective sleep assessment, which might somewhat influence the obtained results and reduce the level of evidence. The authors’ conclusions can be accepted; however, for a more definitive assessment of the impact of cannabis on sleep quality, more detailed clinical studies, utilizing objective sleep quality measurement methods, are necessary.
Our study and the European Insomnia Guideline [52] both emphasize the critical impact of sleep quality on physical and mental health. We align with the guideline in recognizing CBT as the most effective treatment for sleep disorders. The guideline recommends CBT as the first-line treatment for chronic insomnia in adults, both in-person and digitally, which supports our conclusion about its effectiveness. Our study also notes that hypnotherapy is not recommended by several guidelines, which is consistent with the European Insomnia Guideline’s exclusion of hypnotherapy from its recommended treatments. Instead, the guideline suggests pharmacological interventions when CBT is insufficient, recommending specific medications for short-term use, with careful consideration for longer-term use. Both our research and the guideline highlight the importance of comprehensive diagnostic procedures, including clinical interviews and sleep questionnaires, to identify underlying conditions and tailor treatments. Our study also recognizes the strong link between poor sleep and various health issues, including mental health disorders, which the guideline similarly addresses. Additionally, our study suggests exploring psychoanalysis as a potentially effective but underutilized approach for improving sleep quality, an area not covered by the guideline.
Sleep is an important process that attracts the attention of many fields of science and culture. The unresolved features of certain aspects of sleep lead to acute discussions and contradictions in philosophy, psychology, and medicine. In popular culture, these aspects are exploited to endow sleep with characteristics of mystery and mysticism, engaging the audience. However, an indisputable fact is the importance of quality sleep for both physical and mental health, supported by numerous clinical studies and confirmed in this work.
Table 2 summarizes all the articles reviewed in this study.
CONCLUSION
Sleep is a crucial process for the body, and the quality of sleep directly affects physical and mental health. Its quality is determined by indicators such as duration, continuity, and depth. Duration is calculated according to individual needs and changes with age. The recommended sleep time for a healthy adult is 7–8 hours. Continuity characterizes the uninterrupted and gradual transition of sleep phases throughout the entire cycle. Depth is determined by the duration of deep and maximum deep sleep phases, which should ideally constitute 70% and 25% of the total sleep duration, respectively.
The quality of sleep is influenced by internal and external factors, the prolonged action of which leads to sleep disorders such as insomnia, hypersomnia, parasomnia (sleepwalking, somniloquy, sleep paralysis, nightmare disorder), sleep-related breathing disorders (apnoea, snoring, catathrenia), sleep movement disorders (restless legs syndrome, periodic limb movement disorder, sleep-related leg cramps, bruxism). Quality sleep positively affects the overall condition of the body, reducing physical and emotional tension and restoring depleted resources. Reduced sleep quality and the manifestation of sleep disorders lead to: inhibition of motor, regulatory, transport, and protective functions of the body, slowing metabolism, and an increased risk of injury or death due to falls or other damage during episodes of sleepwalking or narcolepsy. Considering that sleep quality and physical health are interdependent indicators, physiological dysfunctions usually lead to the following sleep disorders: insomnia, hypersomnia, apnoea, snoring, catathrenia, restless legs syndrome, periodic limb movement disorder, sleep-related seizures, and bruxism.
Quality sleep and mental health also have a strong connection and can mutually regulate each other. Poor sleep quality and the presence of sleep disorders negatively affect cognitive, emotional, and volitional processes of mental manifestation. Chronic and severe sleep disorders can trigger anxiety and bipolar disorders, depression, paranoia, psychosis, delirium syndrome, phobias, disorders related to dependencies, and obsessive-compulsive disorders. The most effective method of psychotherapy for sleep disorders currently is CBT, while hypnotherapy is not recommended according to several guidelines.
In summarizing the results of the topic analysis, it was established that psychoanalysis is an effective but somewhat underestimated method of psychotherapy. Therefore, as a direction for further research, it is worth exploring the possibility of its application to improve sleep quality. The practical significance of the conducted research lies in the possibility of using its results for the work of general practitioners (family doctors) with patients who have sleep disorders: identifying the presence of a problem, determining its preliminary cause, and directing them to a specialized specialist.
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