• Korean Journal of Child Studies
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• v.37 no.3
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• pp.13-26
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• 2016

Objective: The purpose of this study was to investigate the relationship between sleep duration and school adjustment of elementary-, middle-, high-school youth and to verify the mediating effects of parenting behavior. Methods: We analyzed the data from Wave 4 of the first-grade panel of elementary school and Waves 1 and 4 of the first-grade panel of middle school in Korean Children and Youth Panel Survey (KCYPS), including 1,703 fourth graders, 2,119 seventh graders, and 2,108 tenth graders. Multiple regression was used for the data analyses. Results: The results of this study were as follows. First, longer sleep duration was associated with a higher level of school adjustment in fourth grade. In contrast, longer sleep duration was associated with a lower level of school adjustment in seventh and tenth grades. Second, longer sleep duration was related to a higher level of discipline through reasoning in fourth grade. However, longer sleep duration was related to a lower level of parental monitoring in seventh and tenth grades. Third, the relationship between sleep duration and school adjustment was mediated by parenting behavior. Discipline through reasoning had a mediating effect in fourth grade, but the mediating effect of parental monitoring was found in seventh and tenth grades. Conclusion: These results suggest a differentiated approach on sleep duration in accordance with developmental stage and the need for parent education.

• Korean Journal of Adult Nursing
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• v.21 no.1
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• pp.43-52
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• 2009

Purpose: The purpose of this study was to investigate the relationships between LLFDI and quality of sleep in older men with prostatic hypertrophic symptoms. Methods: The secondary analysis of data collected for the 2nd stage BK(Brain Korea)21 project was performed. The original data were collected using a cross-sectional, face-to-face, and private interview method. The questionnaires consisted of prostatic hypertrophic symptoms, late-life function and disability, quality of sleep, and demographic profiles. Results: A total of 112 older men included in this study. The major findings of this study were as follow; 1) 29.5% of participants had more than moderate symptoms of prostatic hypertrophy. 2) There were a significant positive correlation of prostatic hypertrophic symptoms with subjective sleep quality, sleep latency, sleep disturbances, use of sleeping medication, and daytime dysfunction found, whereas there was a negative relationship with frequency dimension. 3) The LLFDI is significantly associated with urgency, weak stream, and intermittency. The quality of sleep is significantly associated with weak stream which explained 11.2% of variance. Conclusion: These results may contribute to a better understanding late-life function and disability, quality of sleep in older men with prostatic hypertrophic symptoms. Therefore, health programs for prompting older men's health should be planned based on results of the study.

• Sleep Medicine and Psychophysiology
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• v.15 no.2
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• pp.71-76
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• 2008

Introduction: In this study, we compared sleep structure, EEG characteristic of pediatric obstructive sleep apnea (OSA) and normal controls which were matched in sex and age. Methods: Fifteen children (male：female=4：11) who complained snoring and were suspected to have sleep apnea and their age and sex matched normal controls (male：female=5：10) have been done nocturnal polysomnography (NPSG). Sleep parameters, sleep apnea variables and relative spectral components of EEG from NPSG have been compared between both groups. Results: Pediatric OSA group were distinguished from normal controls in terms of apnea index, respiratory disturbance index and nadir of oxyhemoglobulin desaturation. Pediatric OSA group showed increased percent of sleep stage 1, decreased rapid eye movement sleep percent and increased delta power in O1 EEG channel. However other sleep parameters and spectral powers were not different between two groups. Conclusion: In pediatric OSA group, sleep structure parameter disruption may be not prominent as the previous studies for adult OSA group because of including mild OSA data in diagnostic criteria. In addition, EEG changes might not be distinct due to low arousal index compared to adult OSA patients. We can observe general characteristics and particularity of pediatric OSA through this study.

• Sleep Medicine and Psychophysiology
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• v.24 no.2
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• pp.106-117
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• 2017

Objectives: Obstructive sleep apnea (OSA) is a sleep-related breathing disorder that is characterized by repetitive collapse or partial collapse of the upper airway during sleep in spite of ongoing effort to breathe. It is believed that OSA is usually worsened in REM sleep, because muscle tone is suppressed during REM sleep. However, many cases showed a higher apnea-hypopnea index (AHI) during NREM sleep than during REM sleep. We aimed here to determine the characteristics of REM sleep-dependent OSA (REM-OSA) and NREM sleep-dependent OSA (NREM-OSA). Methods: Five hundred sixty polysomnographically confirmed adult OSA subjects were studied retrospectively. All patients were classified into 3 groups based on the ratio between REM-AHI and NREM-AHI. REM-OSA was defined as REM-AHI/NREM-AHI > 2, NREM-OSA as NREM-AHI/REM-AHI > 2, and the rest as sleep stage-independent OSA (IND-OSA). In addition to polysomnography, questionnaires related to subjective sleep quality, daytime sleepiness, and emotion were completed. Chi-square test, ANOVA, and ANCOVA were performed. Results: There was no age difference among subgroups. The REM-OSA group was comprised of large proportions of mild OSA and female OSA patients. These patients experienced poor sleep and more negative emotions than other two groups. The AHI and oxygen desaturation index (ODI) were lowest in REM-OSA. Sleep efficiency and N3 percentage of REM-OSA were higher than in NREM-OSA. The percentage of patients who slept in a supine position was higher in REM-OSA than other subgroups. IND-OSA showed higher BMI and larger neck circumference and abdominal circumference than REM-OSA. The patients with IND-OSA experienced more sleepiness than the other groups. AHI and ODI were highest in IND-OSA. NREM-OSA presented the shortest total sleep time and the lowest sleep efficiency. NREM-OSA showed shorter sleep latency and REM latency and higher percentage of N1 than those of REM-OSA and the highest proportion of those who slept in a lateral position than other subgroups. NREM-OSA revealed the highest composite score on the Horne and ${\ddot{O}}stberg$ questionnaire. With increased AHI severity, the numbers of apnea and hypopnea events during REM sleep decreased, and the numbers of apnea and hypopnea events during NREM sleep increased. The results of ANCOVA after controlling age, sex, BMI, NC, AC, and AHI showed the lowest sleep efficiency, the highest AHI in the supine position, and the highest percentage of waking after sleep onset in NREM-OSA. Conclusion: REM-OSA was associated with the mild form of OSA, female sex, and negative emotions. IND-OSA was associated with the severe form of OSA. NREM-OSA was most closely related to position and showed the lowest sleep efficiency. Sleep stage-dependent characteristics could provide better understanding of OSA.

• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.111-117
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• 1998

Objectives : 'First-night effect' has been a well-known concept since 1960's. It is important because it is one of the major factors to be considered in assessing the reliability of polysomnographic data. However, 'reverse first-night effect' has also been described, resulting in the inconsistency of conceptualization. We attempted to investigate on the first-night effect in adults by having each of them take two nights of polysomnography in a controlled environment. Young healthy adult volunteers were chosen as subjects in order to rule out age- or health-related confounders. Methods : Polysomnography was performed on eight male medical students (mean $age=23.5\;{\pm}\;0.9$) for two nights with Grass model 78 polysomnograph. We scored manually under the standard protocol each epoch of the sleep records. Sleep variables were obtained and compared between the two nights. Results : Sleep period time(SPT) and total sleep time(TST) of the third fraction of night were significantly longer on the first night than on the second night (p<0.05). However, other sleep variables such as percentage of each sleep stage, sleep latency, REM sleep latency, number of waking, and sleep efficiency were not different between the two nights. Conclusion : We could not confirm the existence of first-night effect in this study. In healthy young male adults, it may not happen at all or may happen to a very negligible degree. Young healthy adults may have more adaptability to a new sleep environment. Also, the provision of a reasonably comfortable sleep environment could have helped them with abolition of first-night effect.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.2
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• pp.73-76
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• 2013

Uvulopalatopharyngoplasty (UPPP) is one possibility for the treatment of Obstructive Sleep Apnea (OSA). The aim of this study was study the analysis of polysomnography of pre-UPPP and post-UPPP. All patients were evaluated by means of a physical examination, the epworth sleepiness scale (ESS), the beck depression inventory (BDI) and the nocturnal polysomnography (PSG) before surgery, and 6~12 months after surgery. A total of 15 patients were investigated. All underwent UPPP. The patients were between 26 and 62 years old ($mean{\pm}SD$; $39.7{\pm}10.9$) with a lean body mass index (BMI) of $mean{\pm}SD$; $26.2{\pm}3.0kg/m^2$. The comparison of sleep questionnaires showed that after UPPP, the patients had a significantly lower BMI ($26.2{\pm}3.0kg/m^2$ vs $26.0{\pm}3.4kg/m^2$, p=0.241), ESS ($10.0{\pm}5.4$ vs $6.9{\pm}3.2$, p=0.022), BDI ($9.2{\pm}8.2$ vs $4.2{\pm}4.3$, p=0.343) and higher blood pressure ($127.5{\pm}12.1$ vs $123.7{\pm}12.0$, p=0.272) compared to before UPPP. The comparison of sleep parameters showed that after UPPP, patients had a significantly lower stage N1 ($108.8{\pm}53.1$ vs $82.2{\pm}48.9$, p=0.016), lower sleep latency ($4.9{\pm}4.4$ vs $2.0{\pm}1.7$, p=0.083), a lower total arousal number ($210.6{\pm}90.3$ vs $147.1{\pm}87.3$, p=0.019), lower oxygen desaturation index (ODI) ($30.2{\pm}20.9$ vs $10.2{\pm}15.1$, p=0.006), lower apnea-hypopnea index (AHI) ($31.6{\pm}22.4$ vs $10.9{\pm}15.4$, p=0.005), and a lower respiratory disturbance index (RDI) ($37.4{\pm}21.3$ vs $18.5{\pm}16.5$, p=0.008) compared to after UPPP. The comparison of sleep parameters showed that after UPPP, patients had a significantly higher stage N2 ($154.0{\pm}39.9$ vs $180.5{\pm}49.5$, p=0.017), higher REM ($58.5{\pm}29.7$ vs $72.6{\pm}34.0$, p=0.249), higher $meanSaO_2$ ($94.3{\pm}2.0$ vs $95.9{\pm}0.9$, p=0.043), and higher $meanSaO_2$ ($79.3{\pm}8.5$ vs $83.1{\pm}7.9$, p=0.116) than before UPPP. After UPPP, 6 patients were cured, 2 showed marked improvement, and 7 did not improve. After surgery, the success of the treatment was at 53%. The subjective patient satisfaction was higher than before the surgery.

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.62-71
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• 2017

This paper presents a low-power voltage converter based on a reconfigurable capacitor array. Its energy recycling capacitor array stores the energy during a charge stage and supplies the voltage during an energy recycle stage even after the power source is disconnected. The converter reconfigures the capacitor array step-wise to boost the lost voltage level during the energy recycle stage. Its energy saving is particularly effective when most of the energy remaining in the charge capacitors is wasted by the leakage current during a longer sleep period. Simulations have been conducted using a voltage source of 500 mV to supply a $V_{DD}$ of around 800 mV to a load circuit consisting of four 32-bit adders in a 65-nm CMOS process. Results demonstrate energy recycling efficiency of 85.86% and overall energy saving of 40.14% compared to a conventional converter, when the load circuit is shortly active followed by a long sleep period.

• Sleep Medicine and Psychophysiology
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• v.7 no.1
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• pp.43-50
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• 2000

Objectives: Obstructive sleep apnea syndrome(OSAS) is known to be associated with the changes of autonomic nervous system (ANS). Nasal continuous positive airway pressure(nCPAP) treatment was found to correct abnormal ANS changes in OSAS but it remains to be further clarified. We aimed to assess the effects of nCPAP on ANS manifested on electrocardiogram, using spectrum analysis in the subjects with OSAS. Methods: Digital polysomnography was performed in 18 patients with OSAS(mean age $43.7{\pm}16.6$ years ; 17 males, 1 female ; mean respiratory disturbance index (RDI) $48.6{\pm}20.9$) for one baseline and another CPAP nights. From each night, 300 continuous beats of ECGs without artifact were chosen from both stage 2 sleep and REM sleep and they were used for power spectrum analysis. We compared between baseline and CPAP nights the heart rate variability including VLF(very low frequency power), LF (low frequency power), HF(high frequency power), R-R means, R-R variance, and LF/HF ratio, using Wilcoxon signed ranks test. Results: In all patients, nCPAP proved to be effective in relieving apneas and snoring. During nCPAP night compared with baseline night, decreases in VLF(p<0.05), LF(p<0.01), and R-R variance(p<0.05) were found in stage 2 sleep, and decreased LF(p<0.05) was found in REM sleep. No significant differences in each sleep stage were found in other variables between the two nights. Conclusion: Our findings suggest that OSAS increases the activity of sympathetic nervous system and nCPAP application effectively decreases the activity. And nCPAP does not appear to influence the parasympathetic nervous activity in OSAS.

• Journal of East-West Nursing Research
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• v.29 no.1
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• pp.15-23
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• 2023

Purpose: The purpose of this study was to identify the effect of sleep quality, rehabilitation motivation, depression, and anxiety on quality of life in occupational accident patients. Methods: The participants were 138 patients who in and outpatient treatment at a hospital affiliated with the Korea Workers' Compensation and Welfare-service Hospital located in Daegu and Daejeon. Data were analyzed by independent t-test, ANOVA, Scheffé test, Pearson's correlation coefficients, and hierarchical multiple regression analysis using SPSS/WIN 25.0 program. Results: Quality of life had a significant negative correlation with sleep quality, depression, and anxiety, respectively, but had a significant positive correlation with rehabilitation motivation. Hierarchical multiple regression analysis showed that anxiety was a major factor affecting the quality of life of occupational accident patients. Anxiety showed 42.7% of explanatory power for the quality of life of occupational accident patients. Conclusion: Based on the results of this study, in order to improve the quality of life of patients with occupational accidents, psychological interventions for anxiety should be provided first in the early stage of treatment.

• Tuberculosis and Respiratory Diseases
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• v.47 no.6
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• pp.824-835
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• 1999

Background: Sleep-related breathing disorders are commonly found in patients with chronic renal failure and particularly, sleep apnea may have an influence on the long-term mortality rates in these patients. Maintenance hemodialysis is the mainstay of medical measures for correcting the metabolic derangements of chronic renal failure but it is uncertain whether it may alleviate sleep disorders including sleep apnea. Methods: Forty seven patients on maintenance hemodialysis were surveyed with the sleep questionnaire about their clinical symptoms related to sleep disorders. Among them, 15 patients underwent the polysomnography and their blood levels of urea nitrogen, creatinine, electrolytes and the arterial blood gases in the nights before and following hemodialysis were measured. Results: Forty(85.1%) of the 47 patients complained of the symptoms associated with sleep-wake cycle disturbances, 55.3% experienced snoring and 27.7% reported witnessed apneas. The duration of REM sleep increased significantly in the nights after hemodialysis compared to the nights without hemodialysis(p<0.05) and the percentage of total sleep time comprising NREM sleep decreased significantly in the nights following hemodialysis compared to the nights before hemodialysis(p<0.05). The percentage of total sleep time consisting of the stage 1 and 2 NREM sleep showed the trend for a decrease in the nights after hemodialysis(p=0.051), while the percentage of total sleep time comprising the stage 3 and 4 NREM sleep did not change between nights. The obstructive sleep apnea was more predominant type than the central one in both nights and there were no differences in the apnea index and the apnea-hypopnea index between the nights. The decrease in the blood level of urea nitrogen, creatinine, potassium and phosphorus was observed after hemodialysis(p<0.05), but the differences of parameters measured during polysomnography between the nights did not correlate with the changes of biochemical factors obtained on the two nights. Arterial blood gas analysis showed that pH was significantly greater in the nights after hemodialysis than in the nights before hemodialysis(p<0.05), but there were no correlations between the parameters examined during polysomnography and the parameters of arterial blood gas analysis(p<0.05). Conclusion: These results suggest that chronic renal failure is an important systemic disorder which is strongly associated with sleep disorders. Maintenance hemodialysis, although it is a widely accepted measure to treat chronic renal failure, did not significantly modulate the sleep architecture and the severity of sleep apnea. Thus, taking the patients with chronic renal failure into account, it is advisable to try not only to find a substantial way for correcting metabolic derangements but also to consider the institution of more effective treatments for sleep disorders.