Sleep Reactivity and Sleep Efforts in Shift Workers

Objective@#The current study aimed to investigate the differences in sleep reactivity and sleep effort differs among late night shift workers (LSWs) and non-late night shift workers (non-LSWs), and non-shift workers (non-SWs). @*Methods@#In total, 6,023 participants (1,613 non-SWs, 3,339 LSWs, and 1,071 non-LSWs) were recruited. Non-SWs was defined as those who works at fixed schedules during standard daylight. LSWs was defined as who work late night hours (10 PM–6 AM), while non-LSWs was SWs who did not work during late night. All completed the Ford Insomnia Response to Stress Test (FIRST), the Glasgow Sleep Effort Scale (GSES), the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the Insomnia Severity Index (ISI), and the short-term Center for Epidemiologic Studies-Depression scale (CES-D) through online survey. @*Results@#LSWs and non-LSWs reported higher FIRST, GSES scores than non-SWs. In addition, LSWs reported higher FIRST, GSES scores than non-LSWs. FIRST scores were correlated with CES-D, PSQI, ISI, and ESS for LSWs, non-LSWs, and non-SWs alike. GSES scores were also correlated with CES-D, PSQI, ISI, and ESS for LSWs, non-LSWs, and non-SWs alike. @*Conclusion@#SWs showed higher sleep reactivity and sleep effort than non-SWs. LSWs had higher sleep reactivity and sleep effort than non-LSWs, and these variables are associated with insomnia, daytime sleepiness, and depressive symptoms. Our findings suggests that late night schedule, may increase sleep reactivity and sleep effort, which are associated with sleep and mood disturbances.

Association Between CLOCK Gene Variants and Restless Legs Syndrome in Koreans

Objective@#Previous studies have suggested various causes of restless legs syndrome (RLS), including iron and dopamine concentrations in the brain. Genetic influences have also been reported in many studies. There is also a possibility that circadian clock genes may be involved because symptoms of RLS worsen at night. We investigated whether CLOCK and NPAS2 gene polymorphisms were associated with RLS. @*Methods@#A total of 227 patients with RLS and 229 non-RLS matched controls were assessed according to the International Restless Legs Syndrome Study Group diagnostic criteria. Genotyping was performed using reverse transcription polymerase chain reaction and high-resolution melting curve analyses. @*Results@#Although the genotype distributions of the CLOCK variants (rs1801260 and rs2412646) were not significantly different between patients with RLS and non-RLS controls, the allele frequencies of CLOCK rs1801260 showed marginally significant differences between the two groups (X2 =2.98, p=0.085). Furthermore, there was a significant difference in the distribution of CLOCK haplotypes (rs1801260-rs2412646) between patients with RLS and non-RLS controls (p=0.013). The distributions of allelic, genotypic, and haplotypic variants of NPAS2 (rs2305160 and rs6725296) were not significantly different between the two groups. @*Conclusion@#Our results suggest that CLOCK variants may be associated with decreased susceptibility to RLS.

The Effectiveness of Cognitive Behavioral Therapy on Depressive Symptoms in North Korean Refugees

Objective@#Despite the growing need for psychological programs for North Korean refugees, most psychological interventions for these people lack a verification study that tests their effectiveness. This study aims to evaluate the effectiveness of cognitive behavioral therapy (CBT) in North Korean refugees. @*Methods@#Participants included 38 North Korean refugees, of whom 23 participated in simple relaxation and 15 participated in CBT. The Korean version of the Center for Epidemiologic Studies Depression Scale (CES-D), State-Trait Anxiety Inventory-State (STAI-S), and Impact of Event Scale-Revised were used to evaluate symptoms pre- and post-intervention. @*Results@#Participants had a significant decrease in CES-D scores after treatment (p=0.037). The decrease in CES-D was larger in those who participated in the CBT compared to those in simple relaxation (p=0.023). The superior effects that CBT had on depressive symptoms over simple relaxation were particularly more prominent in those with severe depression (p=0.035). Participants with high levels of anxiety also showed significant decreases in STAI-S scores after treatment, regardless of which type of program they participated in (p=0.023). @*Conclusion@#This preliminary findings suggests that CBT is an effective psychiatric approach in treating depressive symptoms in North Korean refugees, especially for those with a higher degree of depressive symptom.

The Moderating Effect of Sleep Disturbance on the Association of Stress with Impulsivity and Depressed Mood

Objective@#This study was performed to investigate the associations of life event stress with impulsivity, anxiety, and depressed mood as a function of the presence of a sleep disturbance. @*Methods@#In total, 214 participants (age 38.96±10.53 years; 111 females) completed self-report questionnaires, including the Life Experience Survey (LES), Pittsburgh Sleep Quality Index (PSQI), Barratt’s Impulsivity Scale (BIS), Beck Anxiety Inventory (BAI), and Beck Depression Inventory (BDI). The presence of a sleep disturbance was defined as a PSQI score >5. @*Results@#In total, 127 participants presented with a sleep disturbance (age 39.33±10.92 years; 64 females), whereas the remaining 87 did not (age 38.43±9.97 years; 47 females). Negative LES scores were significantly correlated with BIS (r=0.22, p=0.001), BAI (r=0.46, p< 0.001), and BDI (r=0.51, p<0.001) scores, and PSQI scores were significantly correlated with BAI (r=0.49, p<0.001) and BDI (r=0.60, p< 0.001) scores. Moderation analysis revealed statistically significant interactions between negative LES scores and the presence of a sleep disturbance on BIS (p=0.044) and BDI (p=0.014) but not on BAI (p=0.194) scores. @*Conclusion@#The findings of the present study suggest that life event stress has varying degrees of influence on mental health, especially impulsivity and depressed mood, depending on the presence or absence of a sleep disturbance.

Association of the Serotonin 2A Receptor rs6311 Polymorphism with Diurnal Preference in Koreans

Objective@#Evidence for the association between circadian rhythm delay and depression is accumulating. Genetic studies have shown that certain polymorphisms in circadian genes are potential genetic markers of diurnal preference. Along with circadian genes, there is a growing interest in other genetic effects on circadian rhythms. This study evaluated whether the HTR2A rs6311 (-1438C/T) polymorphism is associated with diurnal preference in a Korean population. @*Methods@#A total of 510 healthy subjects were included in this study. All subjects were genotyped for the HTR2A rs6311 polymorphism and they completed the Korean version of the composite scale of morningness (CSM). @*Results@#The C allele carriers (C/C+C/T) showed significantly higher CSM scores compared to C allele non-carriers (T/T) (t=2.22, p= 0.03), suggesting the existence of a morning chronotype tendency in C allele carriers. In other words, the T/T genotype may be associated with the evening chronotype. @*Conclusion@#These results suggest that the HTR2A rs6311 polymorphism may be associated with diurnal preference in a healthy Korean population. The absence of the C allele may be responsible for the increasing susceptibility to eveningness in the Korean population. Further studies on HTR2A polymorphisms that evaluate their interactions with various candidate genes and differences in phenotypic expression of polymorphisms according to ethnic groups are warranted to fully understand their association with diurnal preference.

Insufficient Sleep and Visuospatial Memory Decline during Adolescence / 수면정신생리

OBJECTIVES: The objective of this study was to investigate the correlation between insufficient sleep and visuospatial memory in adolescents using a computerized neurocognitive function test. METHODS: A total of 103 high school students (26 males and 77 females; mean age 17.11 ± 8.50 years) without a serious psychiatric problem was recruited. All subjects were requested to complete a self-report questionnaire about weekday total sleep time and weekend total sleep time. The epworth sleepiness scale (ESS) and the beck depression inventory (BDI) were administered to measure daytime sleepiness and symptoms of depression. Seven subsets of the Cambridge Neuropsychological test automated battery were examined to assess visuospatial memory. RESULTS: After controlling for age, sex, ESS, and BDI, longer weekend total sleep time was correlated with poor performance on delayed matching to sample (r = −0.312, p = 0.002) and immediate recall on pattern recognition memory (r = −0.225, p = 0.025). Increased weekend catch-up sleep time was correlated with poor performance of delayed matching to sample (r = −0.236, p = 0.018), immediate recall on pattern recognition memory (r = −0.220, p = 0.029), and delayed recall on pattern recognition memory (r = −0.211, p = 0.036) after controlling for age, sex, ESS, and BDI. CONCLUSION: This study showed that increased weekend catch-up sleep time reflecting insufficient weekday sleep were associated with poor performance in delayed recall tasks of visual memory. This finding suggests that insufficient sleep during adolescence might produce a decline of visuospatial memory.