• Sleep Medicine and Psychophysiology
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• v.8 no.1
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• pp.22-29
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• 2001

Objectives: Obstructive sleep apnea syndrome (OSA) is a moderately prevalent disorder. Even though much progress has been made in the diagnosis of this disorder, the cost-effectiveness of nocturnal polysomnography is undertermined and physicians and patients are still hesitant to undergo this procedure. The authors wanted to see the validity of chin press/tongue curl maneuver in estimating the severity of OSA which is easy to measure and was originally proposed by Simmons etc. by looking at the correlations between this score and the conventional respiratory disturbance indices. Methods: Forty-three sleep-related breathing disorder patients (28 OSA patients and 15 upper airway resistance syndrome (UARS) patients) who underwent investigation for posssible OSA were studied. Two conventional indices of OSA (apnea/hypopnea index (AHI) and oxygen saturation dip rate (SaO2 dips)), four other sleep variables (lowest SaO2, % of time with SaO2<90% (%SaO2 <90), % of sleep stage 1, mean length of SaO2 dips) and the score of Epworth sleepiness scale (ESS) were compared with the chin press score (CPS) which was newly revised by the author and ranges from 0 to 6. Results: The age of subjects was $45.95{\pm}12.47$ (range 14-76) and their average BMI was $25.98{\pm}3.61$ (range 19.65-37.64). There were no significant differences in age, sex and BMI except repiratory disturbance indices and ESS (p<0.05) between OSA and UARS group. Grouped median CPS of the all subjects was 4.14 (range 1-6). There was a remarkable relationship between CPS and diagnosis category (Likelihood Ratio $X^2$ test; $X^2$=17.41, df=5, p=0.004) and measures of association (Somers' $d=0.65{\pm}0.12$, t=4.83, p=0.000) indicated that CPS increased when the diagnosis changed from UARS to OSA. Spearman's rank correlations between CPS and SaO2 dips (R=0.83), between CPS and AHI (R=0.77) were good (p<0.001). Other variables except mean length of SaO2 dips showed good correlations with CPS as well (p<0.05). Regression analysis indicated that when CPS is 3 there is a provability of 0.35 to have AHI of less than 5. Conclusion: Chin press scores that can be measured easily is well correlation with the conventional sleep apnea indices. They may therefore provide a useful guide in diagnosing obstructive sleep apnea synrome.

• Sleep Medicine and Psychophysiology
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• v.8 no.1
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• pp.30-36
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• 2001

Object: Diurnal variation is included in the diagnostic criteria of the major depressive disorder, melancholic specifier. But there has been controversy over whether diurnal variation is an unique depressive symptoms or a symptom related to a change of sleep patterns, or that of another mechanism, when the previous studies are reviewed. We investigated the existence of diurnal variation according to the subtype of depression and whether diurnal variation is charateristic of melancholic depression or not. We also compared sleep variables according to the existence of diurnal variation. Method: We examined diurnal variation, sleep patterns, severity of depression using the Visual Analogue Mood Scale, Pittsburgh Sleep Quality Index, and Hamilton Depression Rating Scale. Patients recorded their mood state on the Visual Analogue Mood Scale twice a day, morning and evening, for diurnal variation. We divided depressive patients into two groups,-diurnal variation group and nondiurnal variation group,-and compared the mood and sleep variables using SPSS. Results: The frequency of diurnal variation is not significantly different among the subtypes of depression. Significant differences between the diurnal variation group and the nondiurnal variation group existed in middle insomnia and sleep time (p<0.05). In melancholic type, al significant difference between the diurnal variation group and the nondiurnal variation group was noticed in PSQI total, sleep latency, sleep disturbances, daytime dysfunction as well as middle insomnia and sleep time (p<0.05). Conclusions: Diurnal variation existed in other types of depression as well as melancholic type. The results showed that diurnal variation was not a specific symptom of melancholic type, and existence of diurnal variation might be related to sleep patterns.

• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.107-112
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• 2001

Introduction: Narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and cataplexy, is known to be closely associated with the human leukocyte antigen (HLA) DQB1*0602. Several studies have suggested that HLA-DQB1*0602 is strongly linked with narcolepsy-cataplexy. However, no studies have yet been made on whether HLA DQB1*0602 is associated with Korean patients with narcolepsy. This study was designed to investigate the frequency of HLA-DQB1*0602 of Korean patients with narcolepsy. Methods: Twenty patients were selected (mean age: $28.2{\pm}3.0$, 11 men and 9 women). The patients were confirmed to have narcolepsy by the overnight polysomnography and multiple sleep latency test (MSLT) in addition to their clinical history and symptoms at St. Vincent's Hospital and Korea University Hospital Sleep Disorders Clinic. Any subjects co-morbid with other hypersomnic sleep disorders such as sleep apnea or periodic limb movements during sleep were excluded. Clinical data was collected through a semi-structured interview for narcoleptic patients. All patients and 21 control did HLA typing for the presence of DQB1*0602. Results Obtained were as Follows: 1) Mean sleep latency was 2.4 (${\pm}2.0$ minutes) and mean frequency of sleep-onset REM period was 3.0 (${\pm}1.6$) by MSLT. 2) Characteristic symptoms of narcolepsy investigated were as follows: excessive daytime sleepiness (100%), cataplexy (100%), sleep paralysis (60%), hypnagogic hallucination (70%) and disrupted nocturnal sleep (75%). 3) Strong emotional expression such as laughing (80%) and joking (70%) triggered cataplexy which affects the knee and leg region (80%) and jaw region (30%). 4) HLA-DR2 was found in 90% of patients and 35% in controls. The frequency of HLA-DQB1*0602 in patients and controls was 90%, and 24%, respectively. Conclusions: These results, which exhibit high HLA-DQB1*0602 expression in Korean patients with narcolepsy, suggest that HLADQB1*0602 could be a strong genetic marker in narcolepsy.

• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.113-120
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• 2001

Objectives: Obstructive sleep apnea syndrome is common and may produce various symptoms and serious complications. A substantial number of research articles on obstructive sleep apnea syndrome have been published in Korea. However, we found such limitations as lack of sufficient sample size and lack of polysomnography-proven cases. Therefore, we aimed at studying clinical features and sleep structure in a sufficient number of Korean patients with obstructive sleep apnea syndrome diagnostically confirmed with polysomnography. Methods: We studied 801 subjects referred to the Division of Sleep Studies, Seoul National University Hospital, who were diagnosed as having obstructive sleep apnea syndrome with polysomnography. Subjects were excluded if they had central sleep apnea syndrome, periodic limb movement disorder, narcolepsy or REM sleep behavior disorder. Foreign patients were also excluded. First of all, we studied the clinical features of the subjects. Secondly, we compared sleep-related parameters of the study subjects with those of age/sex-matched normal values. Thirdly, correlations of respiratory disturbance index (RDI) with each of the sleep-related parameters were calculated. Results: Among the 801 subjects, 668 were male subjects (83.4%) and 133 female subjects (16.4%). Their mean age was 46.6 years (${\pm}13.5$). The mean body mass index (BMI) was 25.8 (${\pm}3.8$) and subjects with BMI was over 28.0 accounted for 22.8% of the total. Fifty subjects (6.2%) were found to take benzodiazepines. Mean RDI and mean nocturnal oxygen saturation of all subjects was 31.2 (${\pm}24.4$) and 94.5% (${\pm}3.6$), respectively. In comparison with normal values, the subjects showed longer sleep latency, lower sleep efficiency, decreased total slow wave sleep % (TSWS %), and decreased total REM sleep % (TREM %)(p<0.01 in all). RDI had a negative correlation with each TSWS % and TREM % (p<0.01, p<0.01). However, RDI did not have significant correlation with either sleep latency or sleep efficiency. Conclusion: In this study, 6.2% of patients diagnosed as having obstructive sleep apnea syndrome were found to take benzodiazepines, although they are generally considered to be of litte benefit or even dangerous because of the respiratory suppressing effect. The proportion of obese subjects was only 22.8% and Korean patients with obstructive sleep apnea syndrome seem to be less obese than those described in foreign journals. This study also suggests that the severity of obstructive sleep apnea syndrome may have a more significant effect on sleep architecture defined as TSWS % and TREM % than on sleep efficiency.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.38-45
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• 1999

Objectives: We explored the characteristics of physiological variables such as electrodermal response(EDR) and electromyography(EMG) in patients with insomnia, panic disorder, and other anxiety disorders. we aimed to decide the minimum sessions in biofeedback treatment to make the treatment effective and examine the effects of long-term biofeedback treatment by measuring the physiological variables. Methods: Thirty seven outpatients who received biofeedback treatment were divided into 3 groups according to the number of biofeedback sessions(patients who received 4-5 sessions, who received 6-9 sessions, and who received more than 10 sessions). We measured mean and delta values of EDR and EMG levels, and the Hamilton Anxiety Rating Scale(HARS), and Slef-Relaxation Inventory(SRI) in all patients. Data were analyzed by t-test and repeated measures analysis of variance. Results: The mean and delta values of EDR and EMG levels were not different among the 3 groups during the first 4 biofeedback sessions. However, patients who received more than 10 biofeedback sessions had higher baseline mean EDR value(F=2.233, p=0.036) in the first session, compared with other patients. In patients who received more than 10 biofeedback sessions, mean EDR was significantly reduced after $5^{th}$ session(F=10.41, p<0.01). They showed significant improvement in SRI scores at 12th biofeedback session(t=2.726, p<0.05) and in HARS scores at $6^{th}$(t=3.10, p<0.05) and $12^{th}$ biofeedback session(t=10.93, p<0.001). Conclusions: Wesuggest that patients should receive more than 5 biofeedback sessions to experience internal cues and get a good clinical response to biofeedback treatment.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.52-60
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• 1999

Objectives: With the object of finding the appropriate conditions and algorithms for dimensional analysis of human EEG, we calculated correlation dimensions in the various condition of sampling rate and data aquisition time and improved the computation algorithm by taking advantage of bit operation instead of log operation. Methods: EEG signals from 13 scalp lead of a man were digitized with A-D converter under the condition of 12 bit resolution and 1000 Hertz of sampling rate during 32 seconds. From the original data, we made 15 time series data which have different sampling rate of 62.5, 125, 250, 500, 1000 hertz and data acqusition time of 10, 20, 30 second, respectively. New algorithm to shorten the calculation time using bit operation and the Least Trimmed Squares(LTS) estimator to get the optimal slope was applied to these data. Results: The values of the correlation dimension showed the increasing pattern as the data acquisition time becomes longer. The data with sampling rate of 62.5 Hz showed the highest value of correlation dimension regardless of sampling time but the correlation dimension at other sampling rates revealed similar values. The computation with bit operation instead of log operation had a statistically significant effect of shortening of calculation time and LTS method estimated more stably the slope of correlation dimension than the Least Squares estimator. Conclusion: The bit operation and LTS methods were successfully utilized to time-saving and efficient calculation of correlation dimension. In addition, time series of 20-sec length with sampling rate of 125 Hz was adequate to estimate the dimensional complexity of human EEG.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.58-63
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• 2005

Objectives: REM sleep behavior disorder (RBD), characterized by excessive motor activity during REM sleep, is associated with loss of muscle atonia. In recent years, it has been reported that RBD has high co-morbidity with CNS disorders (especially, Parkinson's disease, dementia, multiple system atrophy, etc.). We aimed to assess differences in clinical and polysomnographic findings among RBD patients, depending on the presence or absence of central nervous system (CNS) disorders. Methods: The medical records and polysomnographic data of 81 patients who had been diagnosed as having RBD were reviewed. The patients were classified into two groups: associated RBD (aRBD, i.e., with a clinical history and/or brain MRI evidence of CNS disorder) and idiopathic RBD (iRBD, i.e., without a clinical history and/or brain MRI evidence of CNS disorder) groups. Twenty-one patients (25.9%) belonged to the aRBD group and 60 patients (74.1%) belonged to the iRBD group. The clinical characteristics and polysomnographic findings of the two groups were compared. Results: Periodic limb movement disorder (PLMD), i.e., PLMI (periodic limb movement index)>5, was observed more frequently in the aRBD group than in the iRBD group (p<0.001, Fisher's exact test). Also, obstructive sleep apnea syndrome (OSAS), i.e., RDI (respiratory disturbance index)>5, was found more frequently in the aRBD group (p=0.0042, Fisher's exact test). The percentages for slow wave sleep and sleep efficiency were significantly lower in the aRBD group than in the iRBD group. Conclusion: We found that 1 out of 4 RBD patients had associated CNS disorders, warranting more careful neurological evaluation and follow-up in this category of RBD. In this category of RBD patients, we also found more frequent PLMD and OSAS. These patients were also found to have lower slow wave sleep and sleep efficiency. In summary, RBD patients with associated CNS disorders suffer from more disturbed sleep than those without them.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.39-44
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• 2005

Objectives: Much attention has been paid to sleep apnea syndrome (SAS) in the elderly because of its high prevalence. It is expected that SAS in the elderly has both similarities and differences compared to SAS in the young or middle-aged populations. The aim of this study was to elucidate the characteristics and consequences of SAS in the elderly. Methods: In this study we included 210 young or middle-aged adults between 23 and 59 years (20 women and 190 men) and 65 older adults between 60 and 83 years of age (16 women and 49 men). Respiratory disturbance indices (RDIs) of the study subjects were more than 5 in an overnight polysomnography. They completed the Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI). Informations about body mass index (BMI), neck, waist, and hip measurements, and blood pressure were obtained. Results: No difference was observed between older adults with SAS (older SAS) and adults aged under 60 with SAS (SAS aged under 60) in RDI, apnea index, % time of oxygen saturation less than 90%, and PSQI. Obstructive apnea index and oxygen desaturation index (ODI) were lower in older SAS. Compared to SAS aged under 60, lowest oxygen saturation and central apnea index were higher in older SAS, but they were statistically not significant. BMI and neck circumference were significantly lower in older SAS compared to SAS aged under 60. Diastolic blood pressure was lower in older SAS compared to SAS aged under 60 with no difference in systolic blood pressure. Older SAS showed lower scores in ESS than SAS aged under 60. Significant correlation was observed between RDI and BMI in SAS aged under 60, but not in the case of older SAS. The relationships between RDI and neck circumference, systolic and diastolic pressure, and ESS were similar. Conclusions: The elderly with SAS were not over-weight and there was no relationship between body weight and the severity of SAS. Also, the behavioral and cardiovascular effects of SAS were not marked in the elderly, which might be partly explained by decreased ODI and relatively higher lowest oxygen saturation in older SAS. The normal aging process, aside from increased body weight, might contribute to the development of SAS in the elderly with modest complications.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.32-38
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• 2005

Objectives: Obstructive sleep apnea syndrome (OSAS) has drawn increasing attention as medical community has become to be aware of its co-morbidities and complications, especially cardiovascular complications and excessive daytime sleepiness with accident proneness. As of now, polysomnography is the standard tool to diagnose sleep apnea and estimate the treatment validity. However, its being rather expensive and inconvenient, alternate diagnostic tools have been proposed including wrist actigraphy. So far, actigraphies have been adopted usefully to field-survey sleep apnea prevalence. In this study, we attempted in a sleep laboratory setting to assess the supplemental value of actigraphy in diagnosing OSAS. Methods: This study was done at the Division of Sleep Studies, the Seoul National University Hospital. Thirty-seven clinically suspected cases of OSAS underwent the one-night polysomnography, simultaneously wearing an actigraphy on non-dominant wrist. We analyzed the data of 27 polysomnographically-proven OSAS patients (male：female 20： 7；age $47.6{\pm}12.9$ years old；age range 23 to 72 years) with no other sleep disorders. We calculated RDI (respiratory disturbance index) from the polysomnography data and FI (fragmentation index) from the actigraphy data. Pearson correlation was calculated in order to compare FI with RDI and to evaluate the supplemental diagnostic value of the actigraphy. Results: Mean total sleep time on polysomnography was $401.4{\pm}57.8\;min$ (range of 274.0 to 514.1 min). Mean RDI was $21.7{\pm}20.4/hour$. Mean FI was $21.9{\pm}13.0/hour$. RDI and FI showed significant correlation (r=0.55, p<0.01). Conclusions: Wrist actigraphy in OSAS patients generates a comparable outcome to polysomnography, in measuring the nocturnal sleep fragmentation. The actigraphy could be used supplementally in inpatients, outpatients, and field survey subjects, if polysomnography is unavailable or impossible. In follow-ups related with nasal CPAP (continuous positive airway pressure), upper airway surgery, and oral appliance in OSAS patients, the actigraphy might play a more dominant role in the future.

• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.66-76
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• 1997

Objectives : The purpose of this study is to analyse sleep habits and sleep disorders in the elderly population ased 65-84 years. Methods : Epidemiological survey was performed at home by means of semi structured interviews in the city of Pusan, Korea. Subjects were randomly selected. The questionnaire consisted of 128 items including demographic findings, sleep habits, sleep disorders, somatic illnesses, and psychological distresses. Results : (1) The mean retiring time was 10.28 h (SD 1.30 h) and the mean wake-up time was 5.24 h (SD 1.33 h). The mean duration of sleep was 5.63 h (SD 1.80 h). The mean sleep onset time was 44.51 min. The mean frequency of daytime napping was 2.49 (SD 3.23). The subjects reported they woke up an average of 2.05 (SD 1.59) times per night. All of the above results were not related to age or gender. However, the mean frequency of difficulty in initiating/maintaining sleep was 2.2 times for men and 3.2 times for women (p<0.05). (2) The prevalence of insomnia was 57.7% and was not related to age or gender. Difficulty in initiating sleep was the most commonly reported insomnia complaint(52.4%). Early morning awakening was reported by 50.0% of patients and difficulty in maintaining sleep was reported by 45.1% of them. Worrying in bed and physical pain were strong contributing factor to insomnia. Conclusions : The results of our study showed several characteristics of sleep habits in the elderly. Sleep disorder in old age is not inevitable or trivial. Since sleep disturbance in older adults is common and distressing, it has implications for general health and well-being. Active concern and therapeutic intervention for the sleep habits and sleep disorders in the elderly are needed.