• Sleep Medicine and Psychophysiology
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• v.15 no.1
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• pp.25-32
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• 2008

Objectives: A few studies have compared REM sleep-dependent obstructive sleep apnea syndrome (REM-OSA) with sleep stage non-dependent apnea syndrome (SND-OSA). Despite that REM-OSA might be more common in women than men, no studies have examined the probable characteristics of women patients with obstructive sleep apnea syndrome (OSAS). This study aimed at finding out the characteristics of REM-OSA in women by comparing it with SND-OSA. Methods: Fifty-three subjects diagnosed as OSAS (AHI>5 ; AHI : apnea-hypopnea index) with nocturnal polysomnography at the Center for Sleep and Chronobiology of the Seoul National University Hospital between October 2004 and February 2006 were studied. Of them, 44 subjects with OSAS severity of mild (52 and AHI-NR<15 (AHI-R : AHI during REM sleep, AHI-NR : AHI during non-REM sleep). We compared REM-OSA group with SND-OSA as well as the criteria-determined REM-OSA cases with the visually-determined ones. Results: Among 44 subjects, 28 persons (63.6%) turned out to have REM-OSA by our criteria and 24 persons (54.5%) by visual determination. Statistically significant differences (p<0.05) were found between REM-OSA and SND-OSA groups in AHI, hypopnea index, total sleep time, total wake time, sleep efficiency index, percents of stage 1, 2 and REM sleep, and REM latency. Percent of stage REM sleep (%REM) turned out to have influence on AHI ratio (AHI-R/AHI-NR) (B=0.537, p=0.002). REM-OSA was likely to be diagnosed in milder severity of OSAS (${\chi}^2=13.117$, p<0.001) and those with higher %REM (${\chi}^2=11.325$, p=0.001). There was no significant difference between the criteria-determined and the visually-determined cases of REM-OSA. Conclusion: We suggest that REM-OSA and SND-OSA patients be differentiated in terms of pathophysiology and treatment strategies. Visual determination of REM-OSA might be useful as the screening procedure of REM-OSA. Further studies on women with OSAS and REM-OSA need to be done.

• Fashion & Textile Research Journal
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• v.5 no.1
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• pp.77-81
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• 2003

The purpose of this study was to investigate the effect of multi-functional fabric on EEG and growth hormone (GH) during sleep and quality of sleep with the 9 young female athletes. The subjects participated in separated experimental procedure; sleeping in multi-functional fabric wear (experimental group) and cotton wear (control group) for 450min. During the night (22:00-05:30), we recorded the changes of nocturnal polysomnographic sleep recording and GH were measured every 60min. The results show that there are significant differences in percentage of stage 1, 2 and slow wave sleep (SWS) between two groups(S1, p<.05; S2, SWS, p<.01). The SWS percentage of experimental group is 1.89 times higher than control group. The changes of GH secretion varied depending on two experimental procedures. The peak of GH secretion in experimental group is more than controls by 2.4time (p<.001). The quality of sleep in experimetal group is significantly higher than control (p<.01). These results suggest muti-functional fabric wear is effective in inducing the deep sleep and increasing GH and quality of sleep.

• Research in Community and Public Health Nursing
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• v.30 no.1
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• pp.79-89
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• 2019

Purpose: The purpose of this paper is to determine effects of auricular acupressure on knee pain, range of motion, and sleep in the elderly with knee osteoarthritis. Methods: This is an experimental study designed with randomization and single-blind in a placebo-control approach. The subjects included the elderly with knee osteoarthritis who were using an elderly welfare facility. In each of the groups, 28 subjects were assigned. For the experimental group, auricular acupressure was applied to five pressure points related to the pain caused by osteoarthritis and sleep. In the case of the placebo-control group, auricular acupressure was applied to other five points than the former. The intervention lasted eight weeks. In order to examine intervention effects of auricular acupressure, joint pain, Pressure Pain Thresholds (PPTs), and extension and flexion range of motion (ROM) were measured weekly. As for the preand post-examinations, pain, sleep quality, and the time-by-sleep stage of the patients with knee osteoarthritis were measured. Results: The VAS scores in the experimental group with auricular acupressure significantly decreased through time (p<.001) and WOMAC also significantly decreased (p<.01) compared with the placebo-control group. However, there were no significant differences in PPTs. The flexion (p<.01) and extension (p<.001) ROMs measured for eight weeks improved over time. Meanwhile, sleep quality improved significantly after the intervention termination (p<.01), but there was no significant difference found in the time-by-sleep stage. Conclusion: Auricular acupressure applied for eight weeks was found to be effective in reducing joint pain, improving knee ROM, and improving sleep quality in patients with degenerative knee arthritis.

• Sleep Medicine and Psychophysiology
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• v.8 no.1
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• pp.67-71
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• 2001

Independent Component Analysis (ICA) is a blind source separation method using unsupervised learning and mutual information theory created in the late eighties and developed in the nineties. It has already succeeded in separating eye movement artifacts from human scalp EEG recording. Several characteristic sleep waves such as sleep spindle, K-complex, and positive occipital sharp transient of sleep (POSTS) can be recorded during sleep EEG recording. They are used as stage determining factors of sleep staging and might be reflections of unknown neural sources during sleep. We applied the ICA method to sleep EEG for sleep waves separation. Eighteen channel scalp longitudinal bipolar montage was used for the EEG recording. With the sampling rate of 256Hz, digital EEG data were converted into 18 by n matrix which was used as a original data matrix X. Independent source matrix U (18 by n) was obtained by independent component analysis method ($U=W{\timex}X$, where W is an 18 by 18 matrix obtained by ICA procedures). ICA was applied to the original EEG containing sleep spindle, K-complex, and POSTS. Among the 18 independent components, those containing characteristic shape of sleep waves could be identified. Each independent component was reconstructed into original montage by the product of inverse matrix of W (inv(W)) and U. The reconstructed EEG might be a separation of sleep waves without other components of original EEG matrix X. This result (might) demonstrates that characteristic sleep waves may be separated from original EEG of unknown mixed neural origins by the Independent Component Analysis (ICA) method.

• Korean Journal of Biological Psychiatry
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• v.19 no.1
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• pp.65-69
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• 2012

Objectives : Much is still unknown about the neurophysiological mechanisms or dynamics of the sleep onset process. Detrended fluctuation analysis (DFA) is a new tool for the analysis of electroencephalography (EEG) that may give us additional information about electrophysiological changes. The purpose of this study is to analyze long-range correlations of electroencephalographic signals by DFA and their changes in the sleep onset process. Methods : Thirty channel EEG was recorded in 61 healthy subjects (male:female=34:27, age=$27.2{\pm}3.0$ years). The scaling exponents, alpha, were calculated by DFA and compared between four kinds of 30s sleep-wakefulness states such as wakefulness, transition period, early sleep, and late sleep (stage 1). These four states were selected by the distribution of alpha and theta waves in O1 and O2 electrodes. Results : The scaling exponents, alpha, were significantly different in the four states during sleep onset periods, and also varied with the thirty leads. The interaction between the sleep states and the leads was significant. The means (${\pm}$ standard deviation) of alphas for the states were 0.94 (${\pm}0.12$), 0.98 (${\pm}0.12$), 1.10 (${\pm}0.10$), 1.07 (${\pm}0.07$) in the wakefulness, transitional period, early sleep and late sleep state respectively. The mean alpha of anterior fifteen leads was greater than that of posterior fifteen leads, and the two regions showed the different pattern of changes of the alpha during the sleep onset periods. Conclusions : The characteristic findings in the sleep onset period were the increasing pattern of scaling exponent of DFA, and the pattern was slightly but significantly different between fronto-temporal and parieto-occipital regions. It suggests that the long-range correlations of EEG have a tendency of increasing from wakefulness to early sleep, but anterior and posterior brain regions have different dynamical process. DFA, one of the nonlinear analytical methods for time series, may be a useful tool for the investigation of the sleep onset period.

• Sleep Medicine and Psychophysiology
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• v.2 no.1
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• pp.13-22
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• 1995

To provide the physician with adequate information to diagnose and treat sleepwalking and sleep terrors, the author reviewed clinical features, epidemiology, causative and precipitating factors, polysomnography, diagnosis, differential diagnosis, and treatment for these disorders. Sleepwalking and sleep terrors have been defined as disorders of arousal that occur early in the night and have their onset during stage 3 or 4 sleep. In both disorders, patients are difficult to arouse, and complete amnesia or minimal recall of the episode is frequent. Genetic, developmental, and psychological factors have been identified as causes of both sleepwalking and sleep terrors. Sleepwalking and sleep terrors typically begin in childhood or early adolescence and are usually outgrown by the end of adolescence. When sleepwalking or sleep terrors have a post-pubertal onset or continue to adulthood, psychopathology is a more significant causative factors. The behavior that occur from deep slow-wave sleep can be painful or dangerous to the individual and/or disturbing to those close to that individual. The assessment of patients suspected of having these conditions requires a thorough medical and sleep history. The most important consideration in managing patients with sleepwalking or sleep terrors episodes is protection from injury.

• Sleep Medicine and Psychophysiology
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• v.12 no.2
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• pp.117-121
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• 2005

Objectives: The purpose of this study was to assess the difference of subjective daytime sleepiness level between primary insomnia patients and healthy control subjects. We also investigated the relationship between subjective daytime sleepiness level and variables of nocturnal polysomnograghic sleep architecture of insomnia patients. Method: Total subjects were 87 patients with primary insomnia diagnosed with polysomnography and 88 normal controls. The daytime sleepiness level in each group was measured by Korean version of Epworth Sleepiness Scale (ESS). The correlations of ESS score and nocturnal polysomnographic variables were calculated in the patient group. Results: Patients with insomnia had the lower ESS scores than the control group. In patients group, the ESS score showed significant negative correlations with total sleep time, sleep efficiency%, and stage 2 sleep time%. The ESS score also showed significant positive correlations with number of awakenings, number of awakenings more than 2 minutes, and wake after sleep onset time. Conclusions: Insomnia patients showed lower level of subjective daytime sleepiness that may indicate their higher alertness comparing to control subjects. Daytime sleepiness of patients with insomnia was associated with polysomnographic variables including total sleep time, sleep efficiency%, stage 2 sleep time% and disrupted continuity of nocturnal sleep.

• Sleep Medicine and Psychophysiology
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• v.5 no.2
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• pp.202-209
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• 1998

Authors report the findings of nocturnal polysomnography and multiple sleep latency test(MSLT) before and after morning light treatment in a winter depressive patient with hypersomnia. On polysomnographic recordings, the sleep pattern of this case before light treatment was similar to that of narcolepsy exhibited, sleep onset REM period(SOREMP). After treatment, the shortened REM latency changed to normal condition, but, deep sleep percentage did not changed, and stage 4 sleep percentage was decreased. Depressive symptoms were improved on clinical interview with Hamilton Depressive Rating Scale. Sleep log showed shortened sleep latency and reduced sleep duration. These findings suggest that although light treatment could alter the sleep structure in seasonal affective disorder with hypersomnia, it does not necessarily imply that antidepressant response of light treatment is result of change of sleep structure.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.493-493
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• 2000

Multi-valued decision making for transitional stochastic events was newly derived based on conditional probability of database. The two values (on-off) decision making method without transition had been proposed by one of the author in a previous work for a purpose of realizing human on-off decision making. The current method is an extension of the previous on-off decision making. By combining the conditional probability and the transitional probability, the closed form of the algorithm for the multi-valued transitional decision making was derived. The proposed multi-valued decision making was successfully applied to the determination of the five levels of the vigilance of a subject during the EEG recording; awake stage, drowsy stage and sleeping stages (stage 1, stage 2/3, REM (rapid eye movement)). The method for determining the vigilance level can be directly usable for the two purposes; selection of awake EEG segments for automatic EEG interpretation, and determination of sleep stages through sleep EEG. The proposed multi-valued decision making with a mathematical background of the probability can be applicable widely, in industries and in medical fields for purposes of the multi-valued decision making.

• 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.