• 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.13 no.2
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• pp.67-74
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• 2006

Introduction: Excessive daytime sleepiness and cataplexy are key features of narcolepsy. Modafinil is psychostimulant used in the treatment of narcolepsy. In this study, we evaluated effects of modafinil on nocturnal sleep structure and sleep latency in multiple sleep latency test and clinical features. Methods: Twelve narcoleptic patients (7 male, age: $22.9{\pm}2.6\;yrs$) were participated in the study. All of them had done nocturnal polysomnography (nPSG), multiple sleep latency test (MSLT), clinical symptoms scales and have repeated same procedure after taking 200 mg of modafinil. We have done linear mixed model analysis to describe effects of group, medication and nap time on these measures. Results: Modafinil did not affect clinical scales except PSQI which had been reduced after medication. In this study, Modafinil reduced total sleep time, sleep efficiency and increased wake after sleep onset and percent of arousal during sleep in nocturnal polysomnography and prolonged mean sleep latency in multiple sleep latency tests in both group. Discussion: Modafinil has stimulant effect of central nervous system but its effect on night sleep is less than other psychostimulants such as methylphenidate. We ascertained that modafinil affected total sleep time, sleep efficiency and percent of wake during sleep but did not effect on sleep structure. Modafinil was effective in the management of day time sleepiness. Modafinil can enhance alertness of control group without day time sleepiness.

• Sleep Medicine and Psychophysiology
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• v.18 no.1
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• pp.40-44
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• 2011

Narcolepsy is a sleep disorder, which is characterized by excessive daytime sleepiness (EDS) that is typically associated with cataplexy, sleep fragmentation and other REM sleep-related phenomenon such as sleep paralysis and hypnagogic hallucination. Narcoleptic symptoms can be developed from various medical or neurological disorders. A 17-year-old male patient admitted for the evaluation of EDS which started three-month ago. He slept more than 18 hours a day with cataplexy and hypnagogic hallucination. He was obese with body mass index (BMI) of 30.4 kg/$m^2$. After admission he was newly diagnosed to the thyrotoxicosis. T3 391.2 ng/dL (60-181), free T4 4.38 ng/dL (0.89-1.76), TSH <0.01 ${\mu}IU$/mL (0.35-5.5) were measured. His pulse rate ranged 70-90 beats per minute and blood pressure ranged 150/100-120/70 mmHg. Polysomnography revealed many fragmentations in sleep with many positional changes (81 times/h). Sleep onset latency was 33.5 min, sleep efficiency was 47.9%, and REM latency from sleep onset was delayed to 153.6 min. REM sleep percent was increased to 27.1%. Periodic limb movement index was 13.4/h. In the multiple sleep latency test (MSLT), average sleep latency was 0.4 min and there were noted 3 SOREMPs (Sleep Onset REM sleep period) on 5 trials. We couldn't discriminate the obvious sleep-wake pattern in the actigraph and his HLA DQB1 $^*0602$ type was negative. His thyroid function improved following treatment with methimazole and propranolol. Vital sign maintained within normal range. Cataplexy was controlled with venlafaxine 75 mg. Subjective night sleep continuity and PLMS were improved with clonazepam 0.5 mg, but the EDS were partially improved with modafinil 200-400 mg. Thyrotoxicosis might give confounding role when we were evaluating the EDS, though sleep fragmentation was one of the major symptoms of narcolepsy, but enormous amount of it made us think of the influence of thyroid hormone. The loss of sleep-wake cycle, limited improvement of EDS to the stimulant treatmen, and the cataplexy not supported by HLA DQB1 $^*0602$ should be answered further. We still should rule out idiopathic hypersomnia and measuring CSF hypocretin level would be helpful.

• Sleep Medicine and Psychophysiology
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• v.3 no.1
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• pp.47-55
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• 1996

Narcolepsy is characterized by sleep attack with excessive daytime sleepiness(EDS), cataplexy, sleep paralysis, and hypnagogic hallucination. Paradoxically, narcoleptics tend to complain of frequent arousals and shallow sleep during the night time despite their excessive sleepiness. However, nocturnal sleep fragmentation in narcoleptics is relatively ignored in treatment strategies, compared with sleep attack/EDS and cataplexy. In our paper, we attempted to investigate further on the poor nocturnal sleep in narcoleptics and to discuss possible treatment interventions. Out of consecutively seen patients at Seoul National University Sleep Disorders Clinic and Division of Sleep Studies, we recruited 57 patients, clinically assessed as having sleep attack and/or EDS. Nocturnal polysomnography and multiple sleep latency test(MSLT) were done in each of the subjects. We selected 19 subjects finally diagnosed as narcolepsy(mean age $26.0{\pm}18.3$ years, 16 men and 3 women) for this study, depending on the nocturnal polysomnographic and MSLT findings as well as clinical history and symptomatology. Any subject co-morbid with other hypersomnic sleep disorders such as sleep apnea or periodic limb movements during sleep was excluded. Sleep staging was done using Rechtschaffen and Kales criteria. Sleep parameters were calculated using PSDENT program(Stanford Sleep Clinic, version 1.2) and were compared with the age-matched normal values provided in the program. In narcoleptics, compared with the normal controls, total wake time was found to be significantly increased with significantly decreased sleep efficiency(p<.01, p<.05, respectively), despite no difference of sleep period time and total sleep time between the two groups. Stage 2 sleep%(p<.05), slow wave sleep%(p<.05), and REM sleep%(p<.01) were found to be significantly decreased in narcoleptics compared with normal controls, accompanied by the significant increase of stage 1 sleep%(p<.01). Age showed negative correlation with slow wave sleep%(p<.05). The findings in the present study indicate significant fragmentation of nocturnal sleep in narcoleptics. Reduction of REM sleep% and the total number of REM sleep periods suggests the disturbance of nocturnal REM sleep distribution in narcoleptics. No significant correlations between nocturnal polysomnographic and MSLT variables in narcoleptics suggest that nocturnal sleep disturbance in narcoleptics may be dealt with, in itself, in diagnosing and managing narcolepsy. With the objective demonstration of qualitative and quantitative characteristics of nocturnal and daytime sleep in narcoleptics, we suggest that more attention be paid to the nocturnal sleep fragmentation in narcoleptics and that appropriate treatment interventions such as active drug therapy and/or circadian rhythm-oriented sleep hygiene education be applied as needed.

• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.121-128
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• 2001

Objectives: In narcoleptic patients diagnosed with ICSD (international classification of sleep disorders, 1990) criteria, nocturnal polysomnography, and MSLT (multiple sleep latency test), we tried to find characteristic features of quantitative electroencephalography (QEEG) in a wakeful state. Methods: We compared eight drug-free narcoleptic patients with sex- and age-matched normal controls, using computerized electroencephalographic mapping technique and spectral analysis. Absolute power, relative power, interhemispheric asymmetry, interhemispheric and intrahemispheric coherence, and mean frequency in each frequency band (delta, theta, alpha and beta) were measured and analyzed. Results: Compared with normal controls, narcoleptic patients showed decrease in monopolar interhemispheric coherence of alpha frequency bands in occipital ($O_1/O_2$), parietal ($P_3/P_4$), and temporal ($T_5/T_6$) areas and beta frequency band in the occipital ($O_1/O_2$) area. Monopolar intrahemispheric coherences of alpha frequency bands in left hemispheric areas ($T_3/T_5$, $C_3/P_3$ & $F_3/O_1$) decreased. Decrease of monopolar interhemispheric asymmetry of delta frequency band in the occipital ($O_1/O_2$) area was also noted. The monopolar absolute powers of beta frequency bands decreased in occipital ($O_2,\;O_z$) areas. Conclusion: Decreases in coherences of narcoleptic patients compared with normal controls may indicate fewer posterior neocortical interhemispheric neuronal connections, and fewer left intrahemispheric neuronal connections than normal controls in a wakeful state. Therefore, we suggest that abnormal neurophysiological sites of narcolepsy may involve complex areas such as neocortex and subcortex as well as the brainstem.

• 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.