• Sleep Medicine and Psychophysiology
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• v.29 no.2
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• pp.29-34
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• 2022

Coronavirus disease 2019 (COVID-19), which was a global pandemic caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), is still a serious public health problem. COVID-19 causes various symptoms not only in the respiratory system but also in various parts of the body and has a significant effect on sleep. Insomnia and poor sleep quality were observed at high rates in patients with COVID-19 as well as in the uninfected general population. Obstructive sleep apnea is also considered a risk factor in patients with severe COVID-19. Virus-induced central nervous system damage is likely to be the cause of many sleep disorders in COVID-19, but psychosocial influences also seem to have played a significant role. Sleep problems persisted at high rates for a considerable period after the infection phase was over. More attention and research on the effect of COVID-19 on sleep is needed in the future.

• Sleep Medicine and Psychophysiology
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• v.29 no.1
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• pp.1-3
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• 2022

Sleep is associated with Alzheimer's dementia. Many previous researches have shown that inadequate sleep is one of the risk factors that predict Alzheimer's dementia. The causal mechanism of this association is not clear. Slow wave sleep and REM sleep are critical stages in memory consolidation, and by sequential hypothesis both stages are important. Deposition of amyloid beta and tau, the main pathology of Alzheimer's dementia, are also associated with sleep. This review provides the association of sleep and Alzheimer's dementia, and future research is necessary to examine the specific mechanism of this association between sleep and Alzheimer's dementia, which may lead to an early intervention in sleep.

• Sleep Medicine and Psychophysiology
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• v.29 no.1
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• pp.9-14
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• 2022

Dental sleep medicine is an up-and-coming discipline of dentistry, more specifically an offshoot of oral medicine. It traditionally focuses on sleep-related breathing disorders, such as snoring and obstructive sleep apnea. However, everyday practice shows that also other sleep disorders touch on dentistry, including orofacial pain, xerostomia, and bruxism. Therefore, a new definition has been formulated for dental sleep medicine as following; 'Dental sleep medicine is the discipline concerned with the study of the oral and maxillofacial causes and consequences of sleep-related problems'. It is this article's aim to further introduce the emerging discipline of dental sleep medicine to all professionals working in sleep medicine. This article briefly describes the different dental sleep disorders with special focus on the more remarkable associations between orofacial pain and sleep.

• Sleep Medicine and Psychophysiology
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• v.30 no.1
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• pp.3-8
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• 2023

Periodic limb movement disorder (PLMD) is a sleep-related movement disorder characterized by involuntary, rhythmic limb movements during sleep. While PLMD itself is not considered life-threatening, its association with certain underlying health conditions raises concerns about mortality risks. PLMD has been found to be associated with cardiovascular diseases such as hypertension and cardiovascular disease. The fragmented sleep caused by the repetitive limb movements and associated arousals may contribute to sympathetic activation, chronic sleep disruption, sleep deprivation, and subsequent cardiovascular problems, which can increase mortality risks. The comorbidities and health factors commonly associated with PLMD, such as obesity, diabetes, and chronic kidney disease, may also contribute to increased mortality risks. PLMD is often observed alongside other neurological disorders, including restless legs syndrome (RLS) and Parkinson's disease. The presence of PLMD in these conditions may exacerbate the underlying health issues and potentially contribute to higher mortality rates. Further research is needed to elucidate the specific mechanisms linking PLMD to mortality risks and to develop targeted interventions that address these risks.

• Sleep Medicine and Psychophysiology
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• v.30 no.1
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• pp.9-12
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• 2023

Periodic limb movements during sleep (PLMS) are prevalent in various sleep disorders, such as restless legs syndrome (RLS), periodic limb movements disorder, obstructive sleep apnea (OSA), REM sleep behavior disorder (RBD), and narcolepsy. PLMS has been hypothesized to be related to the decline of dopaminergic transmission. In RLS, PLMS is suggested to be related to iron deficiency and symptom severity. PLMD is a rare sleep disorder, and the role of PLMS in PLMD has not been clearly investigated yet. PLMS in OSA, which remain after proper PAP therapy, may need further management. The clinical relevance of PLMS in RBD and narcolepsy have not been investigated thoroughly and need further studies. Whether PLMS are to be considered as a mere symptom of individual sleep disorders or not can be elucidated through studies investigating the efficacy of therapeutic approaches to reduce PLMS in various sleep disorders.

• Sleep Medicine and Psychophysiology
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• v.5 no.2
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• pp.119-133
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• 1998

Attentional processes facilitate cognitive and behavioral performance in several ways. Attention serves to reduce the amount of information to receive. Attention enables humans to direct themselves to appropriate aspects of external environmental events and internal operations. Attention facilitates the selection of salient information and the allocation of cognitive processing appropriate to that information. Attention is not a unitary process that can be localized to a single neuroanatomical region. Before the cortical registration of sensory information, activation of important subcortical structures occurs, which is called as an orienting response. Once sensory information reaches the sensory cortex, a large number of perceptual processes occur, which provide various levels of perceptual resolution of the critical features of the stimuli. After this preattentional processing, information is integrated within higher cortical(heteromodal) systems in inferior parietal and temporal lobes. At this stage, the processing characteristics can be modified, and the biases of the system have a direct impact on attentional selection. Information flow has been traced through sensory analysis to a processing stage that enables the new information to be focused and modified in relation to preexisting biases. The limbic and paralimbic system play significant roles in modulating attentional response. It is labeled with affective salience and is integrated according to ongoing pressures from the motivational drive system of the hypothalamus. The salience of information greatly influences the allocation of attention. The frontal lobe operate response selection system with a reciprocal interaction with both the attention system of the parietal lobe and the limbic system. In this attentional process, the search with the spatial field is organized and a sequence of attentional responses is generated. Affective, motivational and appectitive impulses from limbic system and hypothalamus trigger response intention, preparation, planning, initiation and control of frontal lobe on this process. The reticular system, which produces ascending activation, catalyzes the overall system and increases attentional capacity. Also additional energetic pressures are created by the hypothalamus. As psychophysiological measurement, skin conductance, pupil diameter, muscle tension, heart rate, alpha wave of EEG can be used. Event related potentials also provide physiological evidence of attention during information process. NI component appears to be an electrophysiological index of selective attention. P3 response is developed during the attention related to stimulus discrimination, evaluation and response.

• Sleep Medicine and Psychophysiology
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• v.20 no.1
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• pp.5-9
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• 2013

One of hypothesis is that sleep loss related to a decrease in serotonergic activity plays a significant role in attempted suicide. A growing evidence suggests that central serotonergic activity plays a key role in the etiology of suicide. It has been reported that the cerebrospinal fluid (CSF) levels of 5-hydroxyindoleacetic acid (5-HIAA), the main metabolite of serotonin, were reduced in suicide attempters. In addition, there is evidence that tryptophan hydroxylase is associated with suicide. The association between sleep and suicide was also suggested by some researchers. Several recent studies have showed the association between sleep disturbance and suicide rates in patients with mental disorders and in a general population. In addition, it has been suggested that serotonin plays a role in maintaining arousal and regulating muscle tone and in regulating some of the phasic events of REM sleep. Especially, it is well-known that 5-HT2 receptors are related to slow wave sleep. In conclusion, it is clear that sleep, serotonin activity, and suicide are linked, although the direction of causation needs clarification. In future, large population-based cohort studies are needed to demonstrate the direction of causation in the relationships between sleep, serotonin activity, and suicide.

• Sleep Medicine and Psychophysiology
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• v.21 no.2
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• pp.51-60
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• 2014

A 'circadian rhythm' is a self-sustained biological rhythm (cycle) that repeats itself approximately every 24 hours. Circadian rhythms are generated by an internal clock, or pacemaker, and persist even in the absence of environmental time cues, collectively termed 'zeitgebers.' Although organisms generate circadian rhythms internally, they are entrained by environmental stimuli, particularly the light-dark cycle. Measurement of the endogenous melatonin rhythm provides relatively reliable surrogate way of assessing the timing of the internal circadian clock. Also, core body temperature and cortisol can be used as markers of circadian rhythms. The sleep-wake cycle, body temperature, and melatonin rhythm have a stable internal phase relationship in humans and other diurnal species. They play an important role in controlling daily behavioral rhythms including task performance, blood pressure, and synthesis and secretion of several hormones. In this review, we address not only the properties, methods of measurement, and markers of circadian rhythms, but also the physiological and psychological importance of human circadian rhythms.

• Sleep Medicine and Psychophysiology
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• v.26 no.2
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• pp.67-74
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• 2019

Anger is a multi-dimensional concept ranging from feeling irritable to violent aggression. A growing body of literature suggests the relevance of sleep in regard to anger. The current study aims to review previous studies on the association between anger and diverse aspects of sleep including sleep disruption, chronotype, sleep disorders and sleep deprivation. An association between sleep and anger has been observed starting in the early stage of life, with sleep of infants or toddlers affecting emotional and behavioral aspects of anger. However, the association between anger and sleep is not clear in adolescents and might be due to the effects of psychosocial factors on both sleep and anger during adolescence. Subjective but not objective sleep disturbances of adults have been also associated with anger. Evening types showed more anger, which might be mediated by psychological characteristics or social jet lag of evening people. Increased anger has also been found in those with insomnia, sleep apnea, or experimental sleep-deprivation. Previous studies have reported that diverse sleep disturbances are related to anger. Future study assessing the various sleep or circadian indices and considering the multidimensional aspects of anger are needed.

• Sleep Medicine and Psychophysiology
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• v.16 no.1
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• pp.5-9
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• 2009

Relatively little is known about the neurobiology of insomnia, despite its wide prevalence and broad medical impact. Although much is still to be learned about the pathophysiology of the disorder, identification, systematic assessment, and appropriate treatment are clearly beneficial to patients. Recent research, using quantitative EEG, polysomnography (PSG), multiple sleep latency test (MSLT) and neuroimaging techniques, suggests that some broad areas can be identified as possible pathophysiological models. Sleep-wake homeostat model hypothesizes a failure in homeostatic regulation of sleep, an attenuated increase in sleep drive with time awake, and/or defective sensing of sleep need. Circadian clock model hypothesizes a dysfunctional circadian clock, resulting in changes in the timing of sleep-wake propensity that are incompatible with normal sleep. Intrinsic sleep-wake state mechanism model suggests that abnormal function of insomnia comprises the systems responsible for expression of the sleep states themselves. Extrinsic over-ride mechanism (stress-response) model suggests that insomnia reflects the consequences of overactivity of one of the systems considered "extrinsic" to normal sleep-wake control. Many current therapies for insomnia are based on these physiological models. Several attempts have been made to create a physiological model that would explain this disorder and could be used as a foundation for treatment. However, it appeared that no model can fully explain and clarify all aspects of insomnia. Future research should be necessary to expand our knowledge on the biological dimensions of insomnia.