• Journal of Oral Medicine and Pain
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• v.34 no.4
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• pp.371-377
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• 2009

Objectives: The aim of this study was to evaluate the differences in the polysomnography data between positional and non-positional obstructive sleep apnea (OSA) patients. Methods: Forty-seven patients diagnosed with OSA were evaluated using full night polysomnography. According to the criteria of Cartwright et al., the patients were classified into two groups with 37 positional (supine apnea-hypopnea index [AHI] $\geq$ 2x's the lateral AHI) and 10 non-positional (supine AHI < 2x's the lateral AHI) OSA patients, and the differences of polysomnography data between the two groups were evaluated. Results: There were no significant differences in demographic variables (age, gender, and BMI), daytime sleepiness, overall AHI, total arousal index, and percent time of snoring between two groups. However, AHI, arousal index, and mean oxygen saturation ($SpO_2$) of the REM sleep stage were significantly more severe in the positional OSA group than the non-positional OSA group. Mean $SpO_2$ and the lowest $SpO_2$ during overall sleep stage were also significantly lower in the positional OSA group than the non-positional OSA group. Conclusions: Our results of differences in the polysomnography data of REM sleep stage suggest that non-positional OSA patients may have higher collapsibility of the oropharyngeal airway during sleep than positional OSA patients.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.387-392
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• 2018

The aim of this study was to determine the statistical significance of heart rate variability(HRV) between sleep stages, Apnea-hypopnea index(AHI) and age in patients with obstructive sleep apnea(OSA). This study evaluated the main parameters of HRV over time domain and frequency domain in 40 patients with sleep apnea. The non-REM(sleep stage) was statistically validated by comparing the AHI degree of the three groups(mild, moderate, severe) of sleep apnea patients. The NN50(p=0.043), pNN50(p=0.044), VLF peak(p=0.022), LF/HF(p=0.028) were statistically significant in the R-R interval of patients with sleep apnea from the control group (p<0.05). The LF / HF (p = 0.045) and HF power (p = 0.0395) parameters between the non-RAM sleep (sleep 2 phase) and REM sleep in patients with sleep apnea were statistically significant in the control group(p<0.05). We may be able to provide a basis for understanding the correlation among AHI, sleep stage and age and heart rate variability in patients with obstructive sleep apnea.

• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.83-89
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• 2001

In all ages and countries, dreaming has always been a topic that has interested people. Throughout history, theories about dreaming have been heavily dependent on concurrent theories in related domains. Many researchers have claimed that dreaming occurs during REM and NREM sleep and have rejected the strict association between REM sleep mechanisms and dreams. Although dreams may occur in both REM and NREM periods, they are likely to be produced by different mechanisms during REM and NREM sleep. All physicians managing dreaming-related problems in clinical practice need to understand the multidimensional aspects of dreaming. Therefore, I have reviewed the literature on mechanisms generating and the meaning of dreaming in the neurobiological and psychophysiological perspectives.

• Sleep Medicine and Psychophysiology
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• v.8 no.1
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• pp.18-21
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• 2001

The change of sleep pattern is one of the most often altered normal physiological functions in elderly people. Besides normal change of sleep, insomnia and sleep apnea syndrome (SAS) are (one of) the main complaints. In addition, parasomnia is also frequent in this age group. Several parasomnias frequently found in the elderly are reviewed. Periodic limb movements in sleep (PLMS), restless legs syndrome (RLS), and REM sleep behavior disorder are the most frequent parasomnias in old age. Most parasomnias could be diagnosed by polysomnography, and be treated easily. Therefore, early and precise diagnosis and management for parasomnia in aging people are needed.

• Sleep Medicine and Psychophysiology
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• v.3 no.2
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• pp.43-55
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• 1996

Since REM sleep was found to be closely related with dream, efforts have been made to find the neurophysiological mechanism and the psychological meaning of dream. However, since most researchers have paid attention to dreams of adults, there are relatively few studies devoted to those of developing children. In the prevent study, we reviewed the previous studies and hypotheses about sleep and dream in various aspects and summarized the characteristics of sleep and dream of children in developmental domain as followings. (1) Sleep development : Across childhood, sleep architecture and sleep-wakefulness cycles are progressively changed toward the patterns of adult. They become similar to adult patterns only in their adolescence. Thus, the sleep event sconsidered as abnormal in adults may be normal in children. (2) Dream development : First, the content and meaning of the dream change with increasing age and develop in parallel with children's ego function, especially cognitive developmental stages. Second, for the children, the reality and the dream are on the continuous spectrum of 'reality-imitation-play-fantasy-dream'. Third, dreaming is the pure assimilation process for the children and through dreaming they can adapt and accomodate the reality without emotion.

• Sleep Medicine and Psychophysiology
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• v.4 no.2
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• pp.147-155
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• 1997

To assess the reliability of chronobiological models of sleep/wake regulation, it is necerssary that the models predict the data which has been studied in sleep research, and they should be generalized across all ages. To date, many adult human data on such models have accumulated, yet it is evident that a comprehensive theory of the biorhythmic aspects of sleep/wake states has not established. Circadian rhythms such as the time going to bed, sleep onset, slow wave sleep pressure, periodicity of REM sleep, daytime performance, and early evening alertness are resumed everyday. Even in adult humans, sleep is inherently polyphasic. In both the disentrained and entrained states, naps when allowed tend to recur in a temporally lawful manner. The monophasic sleep pattern of most industrial societies therefore appears to be purely of social origin. The endogenous biorhythmic nature of circasemidian sleep tendency is supported by the ubiquity of the phenomenon across all ages. The NREM/REM sleep cycle within sleep with its inherent physiological, endocrine, and neurochemical fluctuations represents the best-documented ultradian sleep rhythms. Also, a daytime ultradian variation in sleepiness with a periodicity similar to nocturnal NREM/REM cycle(BRAC hypothesis) is suggested. This review article provides a brief synoptic review of the evidences for circadian, circasemidian, and ultradian sleep/wake rhythms, and then the authour will suggest the issues which expedite fuller modeling of sleep/wake system, to be further discussed.

• Journal of Biomedical Engineering Research
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• v.35 no.3
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• pp.55-61
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• 2014

In sleep monitoring system, polysomnography (PSG) is the gold-standard but previous studies revealed that attaching numerous amount of sensors disturb sleep during the test which is the fundamental disadvantage of PSG. We suggest an unconstrained rapid-eye-movement (REM) sleep monitoring method measured with polyvinylidene (PVDF) film-based sensor for the normal and the obstructive sleep apnea (OSA) patients. Nine normal subjects and seventeen OSA patients have participated in the study. During REM sleep, rate and variability of respiration are known to be greater than in other sleep stages. Based on this phenomena, respiratory signals of participants were unconstrainedly measured using the PVDF-based sensor with the PSG and REM sleep were extracted from the average rate and variability of respiration. In epoch-by-epoch REM sleep detection, proposed method classified REM sleep with an average sensitivity of 72.3%, specificity of 92.5%, accuracy of 88.9%, and kappa statistic of 0.60 compared to the results of PSG. Student's t-test showed no significant difference between the results of normal and OSA group. This method is potentially applicable to REM sleep detection in homing environment or ambulatory monitoring.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.5-10
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• 2005

Study in the field of sleep and memory has greatly expanded recently and the number of publications supporting the association between sleep and memory consolidation is rapidly growing. This study presents evidence related to sleep-dependent memory consolidation, ranging from behavioral task-performing studies to molecular studies, and several arguments against the association. Basic researches show that many genes are upwardly regulated during sleep and patterns of brain activation seen during daytime task training are repeated during subsequent REM sleep. Several electrophysiological studies demonstrate the correlation between spindle density increase following training and subsequent improvement in performing the training task. Overnight improvement or deterioration in task performance correlates with REM or SWS sleep. In the end, a lot of issues remain to be studied and discussed further in the future in spite of supporting evidence now available.

• Sleep Medicine and Psychophysiology
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• v.16 no.2
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• pp.49-55
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• 2009

This review aims to introduce the basic neurobiological aspects of dream. There have been long debates on whether the neurobiology of rapid eye movement (REM) sleep is identical to that of dream. However, many theories on dream are based on the findings of REM sleep. Bizarre cognition and intense emotion in dream have been suggested to derive from physiological (e.g. desynchronized gamma oscillation and postsynaptic inhibition), chemical (e.g. decreased noradrenalin and serotonin, increased acetylcholine and modulation of dopamine), anatomical (e.g. deactivation of dorsolateral prefrontal cortex and activation of limbic and paralimbic areas) change in REM sleep. In addition, dream has been suggested to play its neurobiological roles. Processing of negative emotion may be one of the functions of dream. Dream is also supposed to consolidate memory, especially semantic memory. Despite a number of hypotheses and debates, the neurobiological mechanism of dream generation has not been concluded.

• Journal of Oral Medicine and Pain
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• v.38 no.2
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• pp.203-213
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• 2013

Objecives : The purpose of the study was to evaluate treatment outcome of mandibular advancement device(MAD) in obstructive sleep apnea (OSA) patients using full night polysomnography and cephalometry. Methods : Twenty-seven OSA patients were confirmed by full night, lab-attended polysomnography. Cephalometric examinations were conducted to obtain SNA, ANB, $AH{\bot}MP$, AH-C3, SPT, PNS-U, NAS, SOAS, MOAS, and HAS. Mandibular advancement devices (MADs) were fabricated and delivered for all subjects. After acclimation period of MAD, the second polysomnographic examinations were conducted in the same manner. Polysomnographic variables were compared between before and after MAD placement. Also, correlation coefficients were calculated between apnea-hypopnea index (AHI) and each item of cephalometric parameters. Results : There were significant improvements in total AHI, lowest $SpO_2$, and total arousal index after MAD therapy. Also, there were significant improvements in NREM $SpO_2$ and NREM AHI, but not in REM $SpO_2$ and REM AHI with MAD. Stratifying the sleep stage, there were significant decrease in stage I and significant increases in stage II and REM, but change in stage III was not significant. SNA and SOAS were significantly correlated with total AHI and NAS was significantly correlated with supine AHI. ANB was significantly associate with the effect of MAD. Conclusions : MAD is an effective treatment in OSA patients comparing polysomnographic variables before and after treatment. Cephalometric examination can be useful to evaluate OSA patients and predict treatment outcome of MAD.