Sleep medicine is a relatively new field to which medical practitioners have a limited exposure. During the last 20 years, many categories of sleep disorders have been defined. Sleep disorders produce various, sometimes serious, symptoms that cause physical, neuropsychological, and psychiatric problems. Medical doctors should recognize what symptoms are related to sleep disorders and make a first step to establish treatment plans that can help the patients. Based on sleep pharmacology we can understand the mechanisms of sleep physiology and ultimately can make appropriate prescriptions for patients. In Korea, actually, the physicians usually prescribe hypnotics indiscriminately for sleep problems, without considering any various sleep disorders and precise diagnostic procedures. Insomnia is not a simple homogenous disease entity, thus the exact diagnosis is essential for appropriate treatment. Especially, primary insomnia has a psychophysiological origin. Hypnotic medication is just one of the several treatment modalities for insomnia. To certain patients, behavioral modifications, rather than hypnotics, are effective. In fact, antidepressants and benzodiazepines can aggravate certain sleep disorders. In this article, the author reviews nonpharmacological treatment of insomnia, the medication specific to different sleep disorders, and treatment guidelines of hypnotics.
Antidepressive Agents ; Benzodiazepines ; Diagnosis ; Humans ; Hypnotics and Sedatives ; Korea ; Pharmacology ; Physiology ; Prescriptions ; Sleep Wake Disorders* ; Sleep Initiation and Maintenance Disorders

OBJECTIVE: Diurnal preference is an attribute reflecting whether people are alert and preferring to be active either early or late in the day. It also referred to as chronotype or morningness-eveningness trait. The PER3 genes have been known to influence diurnal preference. In this study, we have investigated the associations between the PER3 gene polymorphisms and diurnal preference in a healthy young population, controlling for the social and environmental confounding factors. METHODS: The participants in this experiment included 299 unrelated medical college students (M=191, F=108), with a mean age of 22.9 years. Diurnal preference was measured by a single administration of the 13-item Composite Scale for Morningness (CSM). Genotyping of the PER3 VNTR (rs57875989) was performed using polymerase chain reaction. A two-tailed alpha of 0.05 was chosen. RESULTS: The mean+/-SD score on the CSM scale for all subjects was 31.90+/-6.39. There was no significant difference in total CSM score between gender groups, although females showed a trend towards higher morningness score. Although PER3 5R/5R showed the tendency towards high CSM scores, there were no significant differences on CSM scores among genotypes and allele status of PER3 VNTR (rs57875989). CONCLUSIONS: We could not confirm that the PER3 VNTR is associated with diurnal preference in a Korean healthy young population. The future studies need to investigate the association between diurnal preference and other polymorphisms of PER3 gene in larger sample of Korean young healthy population.
Alleles ; Female ; Genotype ; Humans ; Polymerase Chain Reaction

OBJECTIVES: The previous studies have suggested genetic vulnerability to restless legs syndrome (RLS) development. The occurrence of antipsychotic-related RLS could also be attributable to differences in genetic susceptibility. This study aimed to investigate whether Retinoid-related orphan receptor A (RORA) gene polymorphism is associated with antipsychotic-related RLS in schizophrenia. METHODS: We assessed symptoms of antipsychotic-induced RLS in 190 Korean schizophrenic patients and divided the subjects into two groups according to the International Restless Legs Syndrome Study Group diagnostic criteria : 1) subjects that met all of the criteria (n=44) and 2) the remaining subjects who were not considered to be RLS patients (n=146). Single-nucleotide polymorphism in the RORA gene was genotyped by PCR in 190 individuals. The chi2-test was conducted to compare differences between two groups. RESULTS: The frequencies of genotype (chi2=0.066, p=0.968) of the RORA gene (rs11071547) did not differ significantly between schizophrenic patients with and without RLS. The difference of allele frequencies (chi2=0.008, p=0.927) of the RORA gene (rs 11071547) between the schizophrenic patients with and without RLS were not significant. CONCLUSION: These results suggest that RORA gene polymorphism does not play a major role in susceptibility to antipsychotic-related RLS in schizophrenia.
Child ; Child, Orphaned ; Circadian Rhythm ; Gene Frequency ; Genetic Predisposition to Disease ; Genotype ; Humans ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Restless Legs Syndrome* ; Schizophrenia*

OBJECTIVES: There are emerging evidences suggest that the development of tardive dyskinesia (TD) is related to the oxidative stress, excitotoxicity, and immune activation. The purpose of this study is to investigate whether single-nucleotide polymorphisms (SNPs) of tumor necrosis factor (TNF)-alpha genes are associated with the susceptibility of TD and schizophrenia. METHODS: We investigated two hundred and eighty Korean schizophrenic patients. The schizophrenic participants consisted of patients with (n=105) and without (n=175) TD who were matched for antipsychotic drug exposure and other relevant variables. The TNF-alpha gene -308G/A SNPs were analyzed by polymerase chain reaction (PCR)-based methods. RESULTS: The frequencies of genotype (chi2=0.33, p=0.848) of the TNF-alpha gene -308 G/A SNP did not differ significantly between schizophrenic patients with and without TD. The difference of allele frequencies (chi2=0.28, p=0.594) of the TNF-alpha gene between the schizophrenic patients with and without TD were not significant. CONCLUSION: These results suggest that the TNF-alpha gene -308 G/A SNPs are not associated with TD and schizophrenia in a Korean population. Further association studies of TD with other candidate genes for cytokines would help us understand the pathophysiological mechanisms of TD.
Cytokines ; Gene Frequency ; Genotype ; Humans ; Movement Disorders ; Oxidative Stress ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Polymorphism, Single Nucleotide ; Schizophrenia ; Tumor Necrosis Factor-alpha

OBJECTIVES: Exposure to light at night has become pervasive in modern society. The impact of dim artificial light at night (dALAN) exposure on sleep and fatigue is not well recognized. We aim to study the impact of dALAN exposure during sleep on human fatigue. METHODS: 30 healthy young male volunteers from 21 to 29 years old were enrolled in the study. They were randomly divided into two groups depending on light intensity (Group A : 5 lux and Group B : 10 lux). Data were gathered from each participant after each night with no light (Night 1) followed by the next night (Night 2) with two different dim light conditions (5 or 10 lux) by means of self-reported fatigue scale. RESULTS: Exposure to dALAN during sleep was significantly associated with increased overall fatigue (F = 19.556, p < 0.001) and ocular discomfort (F = 5.671, p = 0.028). CONCLUSION: We found that dALAN during sleep likely affects human fatigue in some aspects. These findings indicate that dALAN during sleep exerts a negative effect on human fatigue.
Fatigue* ; Humans* ; Male ; Volunteers

To define the distribution of normal corneal topographic patterns of Korean adults and compare them with previously published western data, computerized corneal topography was performed on the randomly selected eye of 232 normal subjects using TMS-1(Computed Anatomy). Recruited subjects were 116 females and 118 males. Mean age of the subjects was 50.5 yr. (range 17 to 86 yr.). The color-coded videokeratographs were classified by a masked observer according to the Bogan et al's classification such as round, oval, symmetric bow tie, asymmetric bow tie, and irregular. The results revealed 16 eyes (6.9%) had round. 31 (13.4%) oval, 42 (18.1%) symmetric bow tie, 99 (42.7%) asymmetric bow tie, and 44 (19.0%) irregular pattern. There was no statistically significant difference in the distribution of topographic pattern between male and female and among the age groups. Our results of topographic patterns show the tendency of more irregular and less round topographic pattern in Korean adults, as compared to that of western adults.
Adult* ; Classification ; Corneal Topography ; Female ; Humans ; Male ; Masks

OBJECTIVES: The retinoid-related orphan receptor A (RORA) gene has been reported to have an impact on circadian rhythm regulation. In this study, we analyzed the relationship between the RORA gene polymorphism and diurnal preference in Korean young adults. METHODS: A population of 504 young adults was included in the study. All subjects were given and completed a 13-item composite scale for morningness (CSM). The RORA gene rs11071547 single-nucleotide polymorphism (SNP) was genotyped by PCR-based methods. RESULTS: CSM score was not associated with genotype or allele carrier status of the RORA rs11071547 SNP. CONCLUSION: This result indicates that the RORA rs11071547 SNP does not play a role in diurnal preference.
Alleles ; Child ; Child, Orphaned ; Circadian Rhythm ; Genotype ; Humans ; Young Adult

OBJECTIVE: To investigate the personality characteristics of patients with upper airway resistance syndrome (UARS) and those of patients with obstructive sleep apnea syndrome (OSAS). METHODS: Eighty-eight patients with UARS and 365 patients with OSAS participated. All patients had a diagnostic full-night attended polysomnography (PSG) and completed the Athens Insomnia Scale (AIS), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Symptom Checklist-90-Revision (SCL-90-R) and Eysenck Personality Questionnaire (EPQ). RESULTS: The UARS group scored significantly higher than the OSAS group on the ESS, AIS, and PSQI (p<0.001). The scores of all SCL-90-R subscales in the UARS group were significantly higher than those in the OSA group (all p<0.001, except for somatization, p=0.016). Patients with UARS scored lower on EPQ-E (extroversion/introversion) (p=0.006) and EPQ-L (lie) (p<0.001) than those with OSA. UARS patients also showed higher scores on EPQ-P (psychoticism) (p=0.002) and EPQ-N (neuroticism) (p<0.001) than OSAS patients. CONCLUSION: Our results suggest that patients with UARS have worse subjective sleep quality than OSAS patients in spite of their better PSG findings. UARS patients tend to have more neurotic and sensitive personalities than patients with OSAS, which may be a cause of the clinical features of UARS.
Airway Resistance* ; Humans ; Polysomnography ; Surveys and Questionnaires ; Sleep Apnea, Obstructive* ; Sleep Initiation and Maintenance Disorders

OBJECTIVE: Light pollution has become a social and health issue. We performed an experimental study to investigate impact of dim light at night (dLAN) on sleep in female subjects, with measurement of salivary melatonin. METHODS: The 25 female subjects (Group A: 12; Group B: 13 subjects) underwent a nocturnal polysomnography (NPSG) session with no light (Night 1) followed by an NPSG session randomly assigned to two conditions (Group A: 5; Group B: 10 lux) during a whole night of sleep (Night 2). Salivary melatonin was measured before and after sleep on each night. For further investigation, the female and male subjects of our previous study were collected (48 subjects), and differences according to gender were compared. RESULTS: dLAN during sleep was significantly associated with decreased total sleep time (TST; F=4.818, p=0.039), sleep efficiency (SE; F=5.072, p=0.034), and Stage R latency (F=4.664, p=0.041) for female subjects, and decreased TST (F=14.971, p<0.001) and SE (F=7.687, p=0.008), and increased wake time after sleep onset (F=6.322, p=0.015) and Stage R (F=5.031, p=0.03), with a night-group interaction (F=4.579, p=0.038) for total sample. However, no significant melatonin changes. There was no significant gender difference of the impact of dLAN on sleep, showing the negative changes in the amount and quality of sleep and the increase in rapid eye movement (REM) sleep in the both gender group under 10 lux condition. CONCLUSION: We found a negative impact of exposure to dLAN on sleep in female as well as in merged subjects. REM sleep showed a pronounced increase under 10 lux than under 5 lux in merged subjects, suggesting the possibility of subtle influences of dLAN on REM sleep.
Female* ; Humans ; Male* ; Melatonin ; Polysomnography ; Sleep, REM

BACKGROUND: The dopaminergic genes have been implicated with some personality traits. Many recent studies indicated that there is a correlation between D2 dopamine receptor gene(DRD2) polymorphisms and the personality traits. The purpose of this study is to investigate a possible association between DRD2 gene (TaqI A, TaqI B) polymorphism and personality traits. METHODS: The subjects were consisted of 173 blood-unrelated young female Koreans with a mean age(+/-SD) of 13.88(+/-0.29) years. These volunteers were recruited from one of the junior high schools in Seoul and were tested by the Korean version of the Temperament and Character Inventory(TCI). Genotyping of the DRD2 polymorphisms by PCR methods were carried out. Two DRD2 gene polymorphisms were classified and individually assessed as follows: TaqI A1+ vs A1-, TaqI B1+ vs B-. The associations between the TCI scores and TaqI A, TaqI B polymorphisms were assessed by Student's t-test. RESULTS: In the 173 subjects, the allele frequencies of the DRD2 TaqI A1, TaqI B1 alleles ranged from 0.42 to 0.43, and these results are quite different from the ranges of 0.15-0.20 in the case of a Caucasian population. The genotype frequencies of DRD2(TaqI A1, TaqI B1) variants showed no significant deviation from the Hardy-Weinberg equilibrium. RD4(dependence vs. independence) of Cloninger's TCI, a sub-dimension of Reward Dependence, was significantly higher in the subjects having DRD2 less frequent alleles than those without these alleles. CONCLUSION: This study suggests that the female subjects carrying the less frequent DRD2 alleles exhibited higher reward-dependent personality trait compared to those without these alleles.
Alleles ; Dopamine* ; Female ; Gene Frequency ; Genotype ; Humans ; Polymerase Chain Reaction ; Receptors, Dopamine* ; Reward* ; Seoul ; Temperament ; Volunteers