Association Between CLOCK Gene Variants and Restless Legs Syndrome in Koreans

The Prevalence and Predictors of Sleep Disorders and Their Impact on Academic Performance Among Saudi University Students: A Cross-Sectional Study

BACKGROUND

University students encounter a variety of sleep problems that have an impact on their health and academic performance. Therefore, the aim of this study was to evaluate the prevalence of sleep disorders and their impact on academic performance among Saudi university students.

METHODS

This is an online cross-sectional study that involved university students and was conducted between November 2022 and February 2023 in Saudi Arabia. Sleep disorders were examined among undergraduate students through online screening surveys including the Epworth Sleepiness Scale (ESS) to assess excessive daytime sleepiness, the Insomnia Severity Index (ISI) to measure insomnia, and the Berlin questionnaire to examine obstructive sleep apnea (OSA). Restless leg syndrome (RLS) was measured using the RLS rating. SPSS version 29.0 (IBM Corp., Armonk, NY, USA) was used for all statistical analyses. Binary logistic regression analysis was used to identify predictors of having excessive daytime sleepiness, insomnia, sleep-disordered breathing, and RLS.

RESULTS

The sample included 449 participants. According to the ESS, 56.6% (n=254) of students reported excessive daytime sleepiness. Using the ISI, 78.4% (n=352) of students were found to have insomnia. The Berlin questionnaire indicated that 6.7% (n=30) of students had sleep-disordered breathing. Additionally, 13.6% (n=61) of students reported having RLS. Male students had higher odds of sleep-disordered breathing compared to females (p<0.01), while marital status showed that married students had higher odds of sleep-disordered breathing (p<0.05). Students who reported nighttime sleeping had lower odds of insomnia and restless leg syndrome (p<0.05). Having regular sleeping times was associated with higher odds of insomnia (p<0.05). Napping sometimes was associated with higher odds of excessive daytime sleepiness and sleep-disordered breathing (p<0.05). Students working day and night shifts had higher odds of sleep-disordered breathing (p<0.01). Interestingly, students with comorbidities had lower odds of RLS (p<0.01).

CONCLUSION

This study established that sleep disturbances among students significantly reduce grade point averages (GPAs), where the most affected were male students and those who were married. The government should implement sleep education programs, provide resources for the management of sleep, encourage consistent sleep schedules, and come up with targeted interventions for at-risk groups. More research is also recommended on effective sleep interventions.

Genetic Association Studies in Restless Legs Syndrome: Risk Variants & Ethnic Differences

BACKGROUND

Genetic association studies have not produced consistent results in restless legs syndrome (RLS).

OBJECTIVES

To conduct a systematic review on genetic association studies in RLS to highlight the common gene variants and ethnic differences.

METHODOLOGY

We conducted Pubmed, Embase, and Cochrane search using terms "Genetic association studies" and "restless legs syndrome" for candidate gene-based studies. Out of the initial 43 studies, 18 case control studies (from 2012 to 2022) were included. Thirteen studies including 10794 Caucasian subjects (4984 RLS cases and 5810 controls) and five studies involving 2009 Asian subjects (796 RLS cases and 1213 controls) were tabulated and analyzed. In addition, three Genome-Wide Association Studies (GWAS) in Asians and Europeans/Caucasians were included for comparisons.

RESULTS

In the Asian population, gene variants in BST1, SNCA Rep1, IL1B, BTBD9, and MAP2K5/SKOR1 increased the risk of RLS (odds ratio range 1.2-2.8). In Caucasian populations, examples of variants that were associated with an increased risk of RLS (odds ratio range 1.1-1.9) include those in GABRR3 TOX3, ADH1B, HMOX1, GLO1, DCDC2C, BTBD9, SKOR1, and SETBP1. Based on the meta-analysis of GWAS studies, the rs9390170 variant in UTRN gene was identified to be a novel genetic marker for RLS in Asian cohorts, whereas rs113851554 in MEIS1 gene was a strong genetic factor among the >20 identified gene variants for RLS in Caucasian populations.

CONCLUSION

Our systemic review demonstrates that multiple genetic variants modulate risk of RLS in Caucasians (such as MEIS1 BTBD9, MAP2K5) and in Asians (such as BTBD9, MAP2K5, and UTRN).

Why the worsening at rest and worsening at night criteria for Restless Legs Syndrome are listed separately: review of the circadian literature on RLS and suggestions for future directions

The field of circadian research on Restless Legs Syndrome (RLS) and periodic limb movements (PLMs) is reviewed in general. RLS has five obligatory criteria for diagnosis: (1) an urge to move the legs often accompanied by uncomfortable leg sensations; (2) symptoms are worse at rest, i.e., lying or sitting; (3) there is a least partial and temporary relief of symptoms by activity, e.g., walking or stretching or bending the legs; (4) symptoms are worse later in the day or at night; and (5) mimics of RLS such as leg cramps and positional discomfort should be excluded by history and physical. In addition, RLS is frequently accompanied by PLMs, either periodic limb movements of sleep (PLMS) as determined by polysomnography or periodic limb movements while awake (PLMW) as determined by the suggested immobilization test (SIT). Since the criteria for RLS were based upon clinical experience only, an early question after the development of the criteria was whether criteria 2 and 4 were the same or different phenomena. In other words, were RLS patients worse at night only because they were lying down, and were RLS patients worse lying down only because it was night? Early circadian studies performed during recumbency at different times of the day suggest that the uncomfortable sensations, PLMS, and PLMW as well as voluntary movement in response to leg discomfort follow a similar circadian pattern with worsening at night independent of body position and independent of sleep timing or duration. Other studies demonstrated that RLS patients get worse when sitting or lying down independent of the time of day. These studies as a whole suggest that the worsening at rest and the worsening at night criteria for RLS are related but separate phenomena and that criteria 2 and 4 for RLS should be kept separate based upon the circadian studies, as had been the case previously based upon clinical grounds alone. To more fully prove the circadian rhythmicity of RLS, studies should be conducted to see if bright light shifts the signs and symptoms of RLS to a different circadian time in concert with circadian markers.

Reassessment of candidate gene studies for idiopathic restless legs syndrome in a large genome-wide association study dataset of European ancestry

Study Objectives

Several candidate gene studies have been published for idiopathic restless legs syndrome (RLS) in populations of European ancestry, but the reported associations have not been confirmed in independent samples. Our aim was to reassess these findings in a large case–control dataset in order to evaluate their validity.

Methods

We screened PubMed for RLS candidate gene studies. We used the genome-wide association study (GWAS) dataset of the International EU-RLS-GENE Consortium as our replication sample, which provided genome-wide single-variant association data based on at most 17 220 individuals of European ancestry. We performed additional gene-based tests using the software MAGMA and assessed the power of our study using the genpwr R package.

Results

We identified 14 studies conducted in European samples which assessed 45 variants in 27 genes of which 5 variants had been reported as significantly associated. None of these individual variants were replicated in our GWAS-based reassessment (nominal p &gt; 0.05) and gene-based tests for the respective five genes ADH1B, GABRR3, HMOX1, MAOA, and VDR, were also nonsignificant (nominal p &gt; 0.05). Our replication dataset was well powered to detect the reported effects, even when adjusting for effect size overestimation due to winner’s curse. Power estimates were close to 100% for all variants.

Conclusion

In summary, none of the significant single-variant associations from candidate gene studies were confirmed in our GWAS dataset. Therefore, these associations were likely false positive. Our observations emphasize the need for large sample sizes and stringent significance thresholds in future association studies for RLS.