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

BACKGROUND AND OBJECTIVES: Obstructive sleep apnea (OSA) is often undiagnosed but is an important risk factor affecting the health of an individual. The level of awareness of the illness among patients with OSA is low and is not correlated with severity of the illness. This study was conducted to compare awareness of OSA symptoms and illness between patients with OSA and simple snorers. MATERIALS AND METHODS: Two hundred eighty-two patients who were suspected of having OSA participated in this study. All subjects underwent overnight polysomnography. Those with an apnea-hypopnea index (AHI) ≥ 5 were classified as the OSA group, while those with an AHI < 5 were classified as the simple snoring group. A sleep questionnaire, which included items on awareness of the illness, OSA, and sleep symptoms, was administered to all subjects and their bed-partners. RESULTS: Simple snorers were much more aware of their symptoms such as snoring, irregular breathing, and apnea than were patients with OSA. Bed-partners of simple snorers were also more aware of the participants' sleep symptoms than were partners of patients with OSA. However, the duration of OSA symptoms was longer in the OSA group. In the correlation analysis, the level of awareness of OSA symptoms was negatively correlated with AHI, age, body mass index, and Epworth Sleepiness Scale score. Among the sleep questionnaire and polysomnography results, only Pittsburgh Sleep Quality Index was positively correlated with level of awareness of OSA symptoms. The minority of the respondents had heard about the treatment methods of continuous positive airway pressure and oral appliance and preferred them as treatment options. CONCLUSION: This study suggests that simple snorers are more aware of their symptoms than are patients with OSA. A higher severity of OSA, represented by a higher AHI, is correlated with lower awareness of one's OSA symptoms.
Apnea ; Body Mass Index ; Continuous Positive Airway Pressure ; Humans ; Polysomnography ; Respiration ; Risk Factors ; Sleep Apnea, Obstructive* ; Snoring* ; Surveys and Questionnaires

Since its development in the early 70s, actigraphy has been widely used in sleep research and clinical sleep medicine as an assessment tool of sleep and sleep-wake cycles. The validation and reliability of actigraphic measures have been reasonably examined in healthy normal individuals with good sleep patterns. Recent literature suggests that the use of actigraphy could be further extended to monitor insomnia and circadian sleep-wake disturbances, and detect sleep changes associated with drug treatments and non-pharmacologic interventions, although it is generally recommended to use complementary assessments such as sleep diaries and overnight polysomnography when possible. The development of actigraphy includes its improved hardware sensors for better detection of movements and advanced algorithms to score sleep and wake epochs. In this paper, we briefly review the quantitative analysis methods of actigraphy and its potential applications in sleep research.
Actigraphy* ; Polysomnography ; Sleep Initiation and Maintenance Disorders

Previous research has identified the biological, psychological, and social factors that confer an elevated risk for suicide. Evidence suggests that sleep disturbances are one of the risk factors that predict an increased risk for suicidal behaviors. Both sleep disorders and general sleep complaints are linked to higher levels of suicidal ideation and depression, as well as increased rates of suicide and suicide attempts. The causal mechanism of this association is not clear. For example, it is not known if insomnia is an independent phenomenon that if interrupted could prevent the emergence of a mental disorder, or if insomnia is a symptom of another developing illness. Hypofrontality, HPA dysfunction, and an impaired serotonergic system are potential mechanisms underlying the association of sleep disturbances and suicidal behavior. Future research is necessary to examine the specific mechanism of this association between sleep and suicide, which may lead to an effective intervention and diminished suicide risk.
Depression ; Frontal Lobe ; Mental Disorders ; Risk Factors ; Serotonin ; Sleep Initiation and Maintenance Disorders ; Sleep Wake Disorders ; Suicidal Ideation ; Suicide*

OBJECTIVES: Previous studies have reported an association between circadian preference and personality. Defense mechanism is unconscious ego process which deals with an individual's anxiety and is closely associated with one's personality. Our aim is to investigate the association between defense mechanism and circadian preference in medical students. METHODS: One hundred forty eight medical students (70 males, 78 females), aged 22 to 30, answered the Beck Depression Inventory-II, Morningness-eveningness Questionnaire, and Korean version of Defense Style Questinnaire. RESULTS: Consumption (beta=-0.262, p=0.001) and being a male (beta=0.175, p=0.031) were significant positive predictors of eveningness, while sublimation (beta=0.185, p=0.023) was a significant negative predictor of eveningness. CONCLUSION: Our study showed a relationship between specific defense mechanisms (i.e., consumption and sublimation) and eveningness in medical students, but it did not address whether the relationship is a causal one.
Anxiety ; Defense Mechanisms ; Depression ; Ego ; Humans ; Male ; Surveys and Questionnaires ; Students, Medical* ; Sublimation*

OBJECTIVES: There are a lot of studies that analyze the interaction between the emotion of disgust and the functional brain images using fMRI and PET. But studies using sLORETA (standardized low resolution brain electromagnetic tomography) almost do not exist. The aim of this research is to explore the relationship of the emotion of disgust and the cortical activation using sLORETA analysis. METHODS: Forty five healthy young adults (27.1+/-2.6 years) participated in the study. While they were watching 4 neutral images and 4 disgusting images associated with mutilation selected from the international affective picture system (IAPS), participants' EEGs were taken for 30 seconds per one picture. Through these obtained EEG data, sLORETA analysis was performed to compare EEGs associated with neutral and negative images. RESULTS: During looking for visual disgusting stimulus, all participants reported unpleasantness, arousal and stress. In sLORETA analysis, the decrease of current density in theta wave was shown at left frontal superior gyrus (BA10) and middle gyrus (BA10, 11). This voxel cluster consists of a total of 11 voxels and the threshold of t value indicating statistically significant decreases in the current density (p<0.05) was -1.984. There were no differences between male and female in the degree of being disgusted by the stimuli. CONCLUSION: This finding may suggest that the activation of dorsolateral prefrontal cortex might be associated with regulating disgust emotion.
Arousal ; Brain ; Electroencephalography ; Female ; Humans ; Magnetic Resonance Imaging ; Magnets ; Male ; Prefrontal Cortex ; Young Adult

INTRODUCTION: Although it is well known that medical students are not getting an adequate amount of sleep, there have been only a few studies on the sleep patterns of medical students and the related factors. Therefore, the present study aimed to investigate the medical students' sleep patterns and the related factors. METHODS: A questionnaire package was administered to the 1st to 4th year medical students at one medical school. It consisted of questions asking about their lifestyles as well as Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale (ESS), global assessment of recent stress scale (GASS), the center for epidemiologic studies-depression scale (CES-D), and Moudsley obsessive-compulsive inventory (MOCI). A total of 352 students (206 males and 146 females) responded to the survey and the result was analyzed using the independent t-test, the chi-square test, the paired t-test, Pearson's correlation and ANOVA. p-values of less than 0.05 were considered statistically significant in analyses. RESULTS: The weekend bedtime was significantly delayed (0 : 49 on weekday ; 1 : 34 on weekend ; t=-5.23, p<0.001), the weekend rise time was delayed (6 : 58 on weekday ; 9 : 30 on weekend ; t=-24.48, p<0.001) and the total sleep time was increased on weekends (5 : 36 on weekday ; 7 : 39 on weekend ; t=15.94, p<0.001). The PSQI score of all subjects was 6.43+/-2.64. PSQI was positively correlated with ESS (r=0.383, p<0.001), GASS (r=0.326, p<0.001), CES-D (r=0.393, p<0.001), and MOCI (r=0.247, p<0.001), but not with GPA (r=0.072, p=0.228. The more senior students had lower PSQI, GASS, CES-D, and MOCI score (p<0.05). CONCLUSION: Medical students were experiencing a lack of sleep during weekdays as they have a later bedtime and earlier rise time, and consequently had more hours of sleep on weekends. Overall, the medical students were experiencing poor sleep quality and sleep deprivation. Poor sleep quality is associated with psychological problems (daytime sleepiness, stress, depression, and obsessive tendency).
Depression ; Humans ; Life Style ; Male ; Surveys and Questionnaires ; Schools, Medical ; Sleep Deprivation ; Students, Medical*

OBJECTIVES: Several evidence has been suggested that the circadian gene variants contribute to the pathogenesis of seasonal affective disorder. In this study, we aimed to investigate the polymorphism in RORA (Retinoid-related orphan receptor A) gene in relation to seasonal variations among healthy young adults in Seoul, Korea. METHODS: A total of 507 young healthy adult subjects were recruited by advertisement. Seasonal variations were assessed by the Seasonality Pattern Assessment Questionnaire (SPAQ). Single-nucleotide polymorphism in the RORA rs11071547 gene was genotyped by PCR in 507 individuals. Considering summer type as confounding factor, we conducted analysis 478 subjects except 29 subjects of summer type. The Chi-square test was conducted to compare differences between groups of seasonals and non-seasonals. Association between genotypes and Global Seasonality Score (GSS) were tested using ANCOVA (Analysis of covariance). RESULTS: In this sample, the prevalence of SAD was 12.1% (winter type 9.3%, summer type 2.8%). There is no significant difference in genotyping distribution of RORA rs11071547 between groups of seasonals and non-seasonals. Global seasonality score (GSS) and scores of all subscales except body weight and appetite were not significantly different between the group with C allele homozygote and the group with T allele homozygote and heterozygote (p-value 0.138). Scores of body weight and appetite were significantly higher in group with C allele homozygotes. CONCLUSION: These results suggest that RORA gene polymorphism play a role in seasonal variations in appetite and body weight and is associated with susceptibility to seasonal affective disorder in some degree in the population studied.
Adult ; Alleles ; Appetite ; Body Weight ; Child ; Child, Orphaned ; Genotype ; Heterozygote ; Homozygote ; Humans ; Korea ; Polymerase Chain Reaction ; Prevalence ; Surveys and Questionnaires ; Seasonal Affective Disorder ; Seasons* ; Seoul ; Young Adult

Alcohol has been used as sedatives historically. The effect of alcohol on sleep is different according to its dose, timing of ingestion, and drinking frequency. Sleep problems may play a role in the development and course of alcohol-related disorders. Insomnia in alcohol-dependent patients is common and early treatment of insomnia may reduce the rate of relapse. Sleep apnea, restless legs syndrome, periodic limbs movement disorder, and altered circadian rhythm may be more frequent in this patients. Management of sleep and alcohol problems is important in treating alcohol-related disorder and sleep disorders, respectively.
Alcohol-Related Disorders ; Circadian Rhythm ; Drinking ; Eating ; Extremities ; Humans ; Hypnotics and Sedatives ; Movement Disorders ; Recurrence ; Restless Legs Syndrome ; Sleep Apnea Syndromes ; Sleep Wake Disorders ; Sleep Initiation and Maintenance Disorders

Autism Spectrum Disorder (ASD) is characterized by persistent deficits in social communication and restricted, repetitive patterns of behavior and interest. Sleep problems are not uncommon in children with autism spectrum disorders. Symptoms of insomnia are the most frequent sleep problems in individuals with ASD. Sleep problems can cause significant difficulties in the daily life of children with ASD and their families. Genetic factor, deregulations of melatonin synthesis, extraneous environmental stimuli and psychiatric and medical conditions may cause sleep problems. The first line treatment of sleep problems in ASD includes managements for potential contributing factors and parent education about sleep hygiene care for child and behavioral therapy. Supplementation with melatonin may be effective before considering other medications, such as risperidone, clonidine, and mirtazapine.
Autistic Disorder* ; Child ; Autism Spectrum Disorder* ; Clonidine ; Education ; Genetics ; Humans ; Hygiene ; Melatonin ; Parents ; Risperidone ; Sleep Initiation and Maintenance Disorders