Sleep structure in sleep bruxism: A polysomnographic study including bruxism activity phenotypes across sleep stages

A population-based study exploring association of parasomnia symptoms with sleep onset delay among school-aged children

OBJECTIVE

Parasomnia is potentially implicated in sleep pattern and sleep architecture, however, evidence is quite limited. This study aimed to investigate the association between parasomnia symptoms and sleep onset delay among children through a large epidemiological study.

METHODS

Two rounds of cross-sectional studies were conducted among 21,704 children aged 3-11; one taking place in Shanghai and the other in Sanya, Hainan province. Children's sleep characteristics were evaluated using the Children's Sleep Habits Questionnaire (CSHQ). Propensity score matching was adopted to balance the difference of covariates, and the logistic regression models were implemented to examine the associations between parasomnia symptoms and sleep onset delay.

RESULTS

A total of 38.2 % of children had sleep onset delay. Parasomnias, especially non rapid eye movement (NREM) and rapid eye movement (REM) parasomnia symptoms, were associated with an increased risk of sleep onset delay (Sleep Walking: OR = 1.55; Sleep Terror: OR = 1.34; Nightmare: OR = 1.37, all p˂0.001). The similar findings were observed in stratified analyses according to sleep duration, and the association was pronounced in sleep sufficiency group (Sleep Walking: OR = 1.62; Sleep Terror: OR = 1.35; Nightmare: OR = 1.35, all p˂0.001). Moreover, a dose-dependent pattern was observed, in which cumulative parasomnia symptoms were associated with increasing risk of sleep onset delay (2 symptoms: OR = 1.19; ≥3 symptoms: OR = 1.40; by comparison with ≤1 symptom). All these findings were also similarly observed in the propensity score matching sample. Moreover, the associations were generally established in both Shanghai and Sanya children.

CONCLUSIONS

Parasomnia symptoms were associated with a higher risk of sleep onset delay independently of sleep duration among children. More studies are needed to enrich the current evidence, thus further clarifying the association and interaction among different sleep parameters.

Inflammatory Markers and Sleep Architecture in Sleep Bruxism-A Case-Control Study

Background: Sleep bruxism (SB) is a common sleep-related movement behavior with a multifaceted etiology and a deficiently understood pathophysiology. A recent hypothesis suggests a link between SB and systemic inflammation. The scope of the study was to determine whether bruxers have altered sleep structure and different levels of inflammatory parameters compared to nonbruxers. Methods: A total of 83 adults underwent full-night polysomnography. The polysomnograms were evaluated using the American Academy of Sleep Medicine (AASM) guidelines. Then, the blood samples were obtained from the participants by venipuncture and the analyses were performed. The study group was divided based on bruxism episode index (BEI) into two groups: BEI ≤ 4 and BEI > 4. Results: In comparison with nonbruxers, the oxygen desaturation index (ODI) was significantly higher in severe bruxers (7.5 ± 11.08 vs. 3.33 ± 5.75, p < 0.005), as well as the arousal parameters (7.77 ± 4.68 vs. 4.03 ± 2.97, p < 0.001), and the mean oxygen desaturation (3.49 ± 0.69 vs. 3.01 ± 0.67, p < 0.05). Moreover, the differences in sleep architecture and deprivation of the deep sleep phase were observed, the non-REM sleep stage 3 was significantly shorter in severe bruxers (p < 0.03). Differences were also noted in non-REM sleep stage 1 and REM sleep phase. In the investigated group, there were no statistical differences in inflammatory cytokines levels between bruxers and nonbruxers. Conclusions: Sleep bruxism is associated with sleep structure alterations and may be associated with deep sleep phase deprivation. The inflammatory markers are not linearly correlated with the severity of sleep bruxism expressed as BEI.

Sleep architecture as a candidate for phenotyping sleep bruxism: A narrative physiological review

BACKGROUND

Sleep bruxism (SB), an oral behaviour in otherwise healthy individuals, is characterised by frequent rhythmic masticatory muscle activity (RMMA) during sleep. RMMA/SB episodes occur over various sleep stages (N1-N3 and rapid eye movement (REM)), sleep cycles (non-REM to REM), and frequently with microarousals. It currently remains unclear whether these characteristics of sleep architecture are phenotype candidates for the genesis of RMMA/SB.

OBJECTIVES

This narrative review investigated the relationship between sleep architecture and the occurrence of RMMA as a SB phenotype candidate.

METHODS

PubMed research was performed using keywords related to RMMA/SB and sleep architecture.

RESULTS

In non-SB and SB healthy individuals, RMMA episodes were most frequent in the light non-REM sleep stages N1 and N2, particularly during the ascending phase of sleep cycles. The onset of RMMA/SB episodes in healthy individuals was preceded by a physiological arousal sequence of autonomic cardiovascular to cortical activation. It was not possible to extract a consistent sleep architecture pattern in the presence of sleep comorbidities. The lack of standardisation and variability between subject complexified the search for specific sleep architecture phenotype(s).

CONCLUSION

In otherwise healthy individuals, the genesis of RMMA/SB episodes is largely affected by oscillations in the sleep stage and cycle as well as the occurrence of microarousal. Furthermore, a specific sleep architecture pattern cannot be confirmed in the presence of sleep comorbidity. Further studies are needed to delineate sleep architecture phenotype candidate(s) that contribute to the more accurate diagnosis of SB and treatment approaches using standardised and innovative methodologies.

Influence of psychiatric symptom profiles of parents on sleep bruxism intensity of their children

OBJECTIVE

The objective of this study was to evaluate the effects of parental anxiety, depression levels and psychiatric symptom profiles of parents on the occurrence of sleep bruxism in children.

MATERIAL & METHODS

This cross-sectional study was carried out with a sample of 94 children aged 6 to 12 years, divided into two groups: with sleep bruxism (bruxism group-BG) and without sleep bruxism (control group-CG). Beck Depression Inventory (BDI), Symptom Checklist (SCL-90-R), Symptom Checklist and Screen for Child Anxiety Related Emotional Disorders-Parent (SCARED-P) scale were used to assess anxiety and depression levels of parents. All questionnaires were filled out by parents of children. Intraoral and extraoral examinations were carried out of children in the clinic and sleep bruxism was determined. All stress conditions were investigated by logistic regression analysis. In the comparison of the qualitative data, chi-square and Fisher exact tests were used.

RESULTS

The data revealed that participants whose mothers had high anxiety and interpersonal sensitivity scores, and participants whose fathers had a medium level of obsessive-compulsive disorder were more likely to have an SB problem (p < 0.05). According to the results of BDI, the fathers' results between the BG and the CG were not statistically significant (p > 0.05). However, the mothers' results between the BG and the CG were statistically significant (p < 0.05) When all subscales of SCARED-P were evaluated, the separation anxiety disorder subscore was statistically significant in the bruxism group.

CONCLUSION

The psychological status of parents is a significant risk factor associated with SB development in school-age children.

Reciprocal first night effect on rhythmic and non-rhythmic oromotor episodes in moderate to severe primary sleep bruxism: A retrospective physiological study

BACKGROUND

Sleep on the first night in a sleep laboratory is characterized by a lower sleep quality and frequency of rhythmic masticatory muscle activity (RMMA) than that on the second night in moderate to severe sleep bruxism (SB) patients.

OBJECTIVE

The aims of this study was to clarify the physiological factors contributing to the first night effect on oromotor activity during sleep and investigate whether physiological factors involved in the first night effect differed between rhythmic and non-rhythmic oromotor activities.

METHODS

Polysomnographic data collected on two consecutive nights from 15 moderate to severe SB subjects (F 7: M 8; age: 23.2 ± 1.3 [mean ± SD] years) were retrospectively analysed. Sleep variables, RMMA and non-specific masticatory muscle activity (NSMA) were scored in relation to episode types (i.e. phasic or tonic and cluster or isolated), sleep architecture and transient arousals. The relationships between nightly differences in oromotor and sleep variables were assessed. The distribution of oromotor events, arousals, cortical electroencephalographic power, RR intervals and heart rate variability were examined in relation to sleep cycle changes. These variables were compared between the first and second nights and between RMMA and NSMA.

RESULTS

Sleep variables showed a lower sleep quality on Night 1 than on Night 2. In comparisons with Night 1, the RMMA index increased by 18.8% (p  < .001, the Wilcoxon signed-rank test) on Night 2, while the NSMA index decreased by 17.9% (p  = .041). Changes in the RMMA index did not correlate with those in sleep variables, while changes in the NSMA index correlated with those in arousal-related variables (p  < .001, Spearman's rank correlation). An increase in the RMMA index on Night 2 was found for the cluster type and stage N1 related to sleep cyclic fluctuations in cortical and cardiac activities. In contrast, the decrease in the NSMA index was associated with increases in the isolated type and the occurrence of stage N2 and wakefulness regardless of the sleep cycle.

CONCLUSION

Discrepancies in first night effect on the occurrence of RMMA and NSMA represent unique sleep-related processes in the genesis of oromotor phenotypes in SB subjects.

The Role of Emotion Regulation, Affect, and Sleep in Individuals With Sleep Bruxism and Those Without: Protocol for a Remote Longitudinal Observational Study

BACKGROUND

Sleep bruxism (SB) is an oral behavior characterized by high levels of repetitive jaw muscle activity during sleep, leading to teeth grinding and clenching, and may develop into a disorder. Despite its prevalence and negative outcomes on oral health and quality of life, there is currently no cure for SB. The etiology of SB remains poorly understood, but recent research suggests a potential role of negative emotions and maladaptive emotion regulation (ER).

OBJECTIVE

This study's primary aim investigates whether ER is impaired in individuals with SB, while controlling for affective and sleep disturbances. The secondary aim tests for the presence of cross-sectional and longitudinal mediation pathways in the bidirectional relationships among SB, ER, affect, and sleep.

METHODS

The study used a nonrandomized repeated-measures observational design and was conducted remotely. Participants aged 18-49 years underwent a 14-day ambulatory assessment. Data collection was carried out using electronic platforms. We assessed trait and state SB and ER alongside affect and sleep variables. We measured SB using self-reported trait questionnaires, ecological momentary assessment (EMA) for real-time reports of SB behavior, and portable electromyography for multinight assessment of rhythmic masticatory muscle activity. We assessed ER through self-reported trait questionnaires, EMA for real-time reports of ER strategies, and heart rate variability derived from an electrocardiography wireless physiological sensor as an objective physiological measure. Participants' trait affect and real-time emotional experiences were obtained using self-reported trait questionnaires and EMA. Sleep patterns and quality were evaluated using self-reported trait questionnaires and sleep diaries, as well as actigraphy as a physiological measure. For the primary objective, analyses will test for maladaptive ER in terms of strategy use frequency and effectiveness as a function of SB using targeted contrasts in the general linear model. Control analyses will be conducted to examine the persistence of the SB-ER relationship after adjusting for affective and sleep measures, as well as demographic variables. For the secondary objective, cross-sectional and longitudinal mediation analyses will test various competing models of directional effects among self-reported and physiological measures of SB, ER, affect, and sleep.

RESULTS

This research received funding in April 2017. Data collection took place from August 2020 to March 2022. In all, 237 participants were eligible and completed the study. Data analysis has not yet started.

CONCLUSIONS

We hope that the effort to thoroughly measure SB and ER using gold standard methods and cutting-edge technology will advance the knowledge of SB. The findings of this study may contribute to a better understanding of the relationship among SB, ER, affect, and sleep disturbances. By identifying the role of ER in SB, the results may pave the way for the development of targeted interventions for SB management to alleviate the pain and distress of those affected.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/41719.

Short-term effect of material type and thickness of occlusal splints on maximum bite force and sleep quality in patients with sleep bruxism: a randomized controlled clinical trial

OBJECTIVE

To evaluate the short-term effects of hard and soft splints of different thicknesses on maximum bite force (MBF) and sleep quality (SQ) in participants with sleep bruxism (SB).

METHODS

One-hundred-fifteen patients were randomly allocated to five groups: Groups H2(Hard splint-2 mm), H3(Hard splint-3 mm), S2(Soft splint-2 mm), S3(Soft splint-3 mm), and C (control). Outcomes were MBF (assessed with a digital gnathodynamometer) and SQ (assessed with the Pittsburgh Sleep Quality Index). Measurements were performed at T0 (before the splints), T1 (1-month follow-up), and T2 (2-months follow-up). Data were analyzed using one-way analysis of variance(ANOVA), Tukey's HSD, and chi-square tests (alpha = 0.05).

RESULTS

At T1, the highest MBF values were observed in group H3 (658.01 ± 22.6 N), while the lowest in group S2 (585.45 ± 8.68 N). For T2, the highest values were obtained in H3 group (676.85 ± 21.9 N), and the lowest in group S2 (565.65 ± 10.9 N) (p < 0.05).For SQ, groups S2 and S3 revealed the lowest PSQI values at T1 (9.1; 9.6) and T2 (9; 9.5) (p < 0.001).

CONCLUSIONS

The short-term use of both 2 and 3-mm thick soft splints resulted in a decrease in MBF. Improvement in SQ in patients using soft splints was observed in the 1st month and was maintained in the 2nd month.

CLINICAL RELEVANCE

This study provides insights on short-term clinical effects as regards to increased sleep quality and regulated maximum bite force as a function of splint material type and the thickness of the splint.

The U-Shaped Association between Sleep Duration, All-Cause Mortality and Cardiovascular Risk in a Hispanic/Latino Clinically Based Cohort

Sleep is essential for life, and inappropriate sleep duration patterns may lead to chronic consequences regarding human health. Several studies have confirmed the presence of a U-shaped association between sleep duration and mortality. Moreover, many consequences related to cardiometabolic aspects have been suggested in patients with abnormal sleep durations. In this study, we analyzed the associations between sleep duration, total sleep time (TST), the risk of all-cause mortality, and 10-year cardiovascular risk in a cohort of patients at a sleep medicine center in Santiago, Chile. We conducted a prospective cohort study of patients (SantOSA). A short TST was defined as ≤6 h, a normal TST as 6 to 9 h, and a long TST as ≥9 h. Adjusted hazard ratios (aHRs) for all-cause mortality were calculated. A cross-sectional analysis between TST and 10-year cardiovascular risk (calculated using the Framingham 2008 formula) was determined using logistic regression models. A total of 1385 subjects were included in the results (78% male; median age: 53, interquartile range (IQR): 42-64 years; median BMI: 29.5, IQR: 16.7-33.1). A total of 333 subjects (24%) reported short TSTs, 938 (67.7%) reported normal TSTs, and 114 (8.3%) reported long TSTs. In the fully adjusted model, the association remained significant for short (aHR: 2.51 (1.48-4.25); p-value = 0.01) and long TSTs (aHR: 3.97 (1.53-10.29); p-value = 0.04). Finally, a U-shaped association was found between short and long TSTs, with an increase in cardiovascular risk at 10 years. Compared with normal TSTs, short (≤6 h) and long (≥9 h) TSTs were significantly associated with all-cause mortality and increased 10-year cardiovascular risk.

Temporomandibular Disorders Related Pain among Sleep & Awake Bruxers: A Comparison among Sexes and Age

According to the current international consensus [...].

Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity

STUDY OBJECTIVES

This study investigated the diagnostic accuracy of Sleep Profiler, which relies on ambulatory polysomnography (PSG) with electroencephalogram for sleep bruxism (SB) and examined its episode-by-episode agreement in comparison to PSG equipped with audiovisual recordings (avPSG).

METHODS

This prospective 2-gate study recruited 10 individuals with probable SB and 10 healthy volunteers. Overnight experimental recordings were performed simultaneously using the ambulatory PSG with masseter electromyography and avPSG with masseter and temporalis electromyography. Sleep staging was performed manually for avPSG and automatically or manually for ambulatory PSG. SB episodes were manually scored based on electromyography signals with reference to sleep stages. The episode-by-episode agreement was analyzed by setting avPSG as the reference standard. The sensitivity, specificity, and accuracy for the diagnosis of SB were calculated after optimizing the cutoff values of the episode index and the burst index.

RESULTS

Regarding the episode-by-episode agreement, median sensitivities were 0.825 and positive predictive values were approximately 0.6, regardless of the sleep staging procedure, indicating that approximately 40% of the overall total SB episodes scored by the ambulatory PSG were false positives. Because of overestimation of SB episodes, the optimal cutoff values for the episode index and the burst index were approximately 1.5 times higher than the avPSG-based cutoff values and dramatically improved the diagnostic precision metrics for the ambulatory PSG.

CONCLUSIONS

Sleep Profiler can eliminate events during wakefulness by electroencephalogram and may provide a definitive diagnosis in patients with possible SB by applying optimized cutoff values. However, the risk of overestimation must be recognized.

CLINICAL TRIAL REGISTRATION

Registry: UMIN Clinical Trials Registry; Name: Accuracy of Portable PSG Device for Detection of Sleep Bruxism-Related Masseter EMG Muscle Activity; URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000037380; Identifier: UMIN000032793.

CITATION

Abe Y, Nakazato Y, Takaba M, Kawana F, Baba K, Kato T. Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity. J Clin Sleep Med. 2023;19(2):379-392.

Relationships between respiratory and oromotor events differ between motor phenotypes in patients with obstructive sleep apnea

Purpose

The present study investigated the relationship between sleep bruxism (SB) and obstructive sleep apnea (OSA) in relation to the sleep architecture.

Methods

We conducted a cross-sectional study. Polysomnographic recordings were performed on 36 patients. Sleep, respiratory, and oromotor variables, such as rhythmic masticatory muscle activity (RMMA) and non-specific masticatory muscle activity (NSMA), were compared between OSA patients with or without SB. A correlation analysis of the frequency of respiratory and oromotor events in NREM and REM sleep was performed. The frequency of oromotor events following respiratory events was also assessed.

Results

The proportion of REM sleep was higher in OSA patients with SB than in those without SB (p = 0.02). The apnea-hypopnea index (AHI) did not significantly differ between the two groups; however, AHI was approximately 8-fold lower during REM sleep in OSA patients with SB (p = 0.01) and the arousal threshold was also lower (p = 0.04). Although the RMMA index was higher in OSA patients with than in those without SB (p < 0.01), the NSMA index did not significantly differ. The percentage of RMMA following respiratory events was significantly higher in OSA patients with than in those without SB, whereas that of NSMA did not significantly differ. The frequency of oromotor events throughout the whole night positively correlated with AHI. However, regardless of the sleep state, AHI did not correlate with the RMMA index, but positively correlated with the NSMA index.

Conclusion

In consideration of the limitations of the present study, the results obtained indicate that OSA patients with SB have a unique phenotype of OSA and also emphasize the distinct relationship of respiratory events with RMMA and NSMA.

Sleep-related factors and orofacial pain symptoms associated with rhythmic masticatory muscle activity frequency scored by polysomnography recordings: A case-control study

OBJECTIVE

This study aimed to evaluate the influence of the frequency of rhythmic masticatory muscle activity per hour (RMMA/h) scored by polysomnography (PSG) recordings on sleep-related factors and orofacial pain symptoms.

METHODS

According to RMMA/h frequency, participants were assigned either to the control group (i.e., CRMMA, n = 40); or the case group according to high (i.e., HRMMA, n = 12) or low (LRMMA, n = 28) RMMA/h frequency. Fisher's exact (nominal variables), One-way Analysis of Variance followed by post-hoc Tukey (continuous variables) and Poisson Regression tests were used to calculate orofacial pain symptoms and sleep-related breathing, behavior, and architecture differences between controls versus cases at a significance level of 5%.

RESULTS

The CRMMA differed from HRMMA and LRMMA subgroups considering orofacial pain, self-reported tooth clenching or grinding, obstructive sleep apnea (OSA), snoring, and most variables considering sleep architecture (P ≤ 0.05). Multivariate adjusted Poisson regression analysis revealed that bruxers, regardless of RMMA/h frequency, presented a significantly higher prevalence rate (PR) related to orofacial pain (PR 1.68; P = 0.025) and self-reported behavior (PR 1.71; P = 0.012).

CONCLUSION

Significant differences in N1, N2 and N3 stages, arousals, arousal per hour, and sleep onset latency variables were found comparing bruxer with high or low RMMA/h frequency. Compared to controls, bruxers presented higher PR related to headache and self-reported tooth clenching or grinding.

Estimation of gingival crevicular fluid oxidative stress markers in school-aged children and teenagers with insufficient sleep

BACKGROUND

Sleep is crucial for survival. Sleep deprivation causes ROS accumulation and, consequently, oxidative stress. The goal of the study was to evaluate gingival crevicular fluid (GCF) levels of the oxidative stress status hydrogen peroxide (H₂O₂), superoxide glutathione (GSH), and cellular oxidative damage marker malondialdehyde (MDA) in school-aged children and teenagers with insufficient sleep.

METHODS

This study investigated sleep duration in 80 participants from two different developmental stages: school-aged children (6-13 years) and teenagers (14-17 years). GCF samples were obtained from all individuals, and samples were investigated to detect H₂O₂, GSH, and MDA levels using the micro method.

RESULTS

Results reveal that GCF MDA and H₂O₂ in school-age children and teenagers with insufficient sleep were significantly higher than in children with sufficient sleep. GCF GSH with insufficient sleep was insignificantly lower than in children with sufficient sleep. There was no significant difference between school-age and teenage populations.

CONCLUSION

Sleep deprivation causes increased levels of oxidative stress in gingival crevicular fluid, and adequate sleep is essential for maintaining redox balance.

Associations between Insomnia, Daytime Sleepiness, and Depressive Symptoms in Adolescents: A Three-Wave Longitudinal Study

BACKGROUND

Insomnia, daytime sleepiness, and depressive symptoms are prevalent in adolescents. This three-wave prospective study examined the associations between the three symptoms in adolescents.

METHODS

A total of 6995 schoolchildren in 7th and 10th grades (Mean age = 14.86 years) participated in a longitudinal study of behavior and health in Shandong, China. Standardized rating scales were used to assess symptoms of insomnia, daytime sleepiness, and depression in November-December in 2015, 1 year later, and 2 years later.

RESULTS

Insomnia was cross-sectionally associated with 10-14-fold increased odds of daytime sleepiness and 5-9-fold increased odds of depression. Daytime sleepiness was associated with 4-5-fold increased odds of depression. Insomnia, daytime sleepiness, or depression at a later time point was significantly predicted by itself at earlier time points. Insomnia was a significant predictor of daytime sleepiness and depression and a mediator between depression and daytime sleepiness. Daytime sleepiness was a significant predictor of insomnia and a mediator between depression and insomnia. Depression was a significant predictor of insomnia and daytime sleepiness and a mediator between insomnia and daytime sleepiness.

CONCLUSIONS

Insomnia, daytime sleepiness, and depressive symptoms were highly comorbid in adolescents. The associations of insomnia with daytime sleepiness and depression were bidirectional. Depression predicted daytime sleepiness, but not vice versa. Further research is needed to understand the underlying neurobiological mechanisms between insomnia, daytime sleepiness, and depression during adolescence.

Sleep Bruxism Contributes to Motor Activity Increase during Sleep in Apneic and Nonapneic Patients-A Polysomnographic Study

Background: Jaw motor activity (MA) in sleep bruxism (SB) has been demonstrated to accompany lower limb movements. However, it remains unknown whether SB activity coexists with other types of movements and what the possible underlying mechanisms of such temporal coexistence are. In obstructive sleep apnea (OSA), increased movement activity is also reported, including SB activity; however, no studies have compared MA in apneic and nonapneic SB patients. Aim: This cross-sectional study focused on the phenomenon of “big body movements” in patients with either SB or OSA (or both) and intended to identify the primary factors contributing to their appearance, using polysomnography (PSG) recording. Methods: A whole-night videoPSG was carried out in 287 participants, and 124 apneic and 146 nonapneic participants were selected for the study. In both groups, participants were further divided into no SB, moderate SB, and severe SB (SSB) subgroups based on their bruxism episode index (BEI). MA was recorded using a built-in sensor of the central PSG unit located on the participant’s chest during the examination. Results: The presence of SB was related to the higher intensity of MA in both apneic and nonapneic participants, though in general the MA level was higher in apneic participants, with the highest level observed in SSB apneic participants. Conclusions: SB might contribute to MA. The prevalence of SB might be higher in nonapneic patients due to phasic and mixed SB activity, whereas the SB phenotype seems to be less relevant in apneic patients. SB activity is likely to increase MA in non-REM 1 sleep.

Incidence of Sleep Bruxism in Different Phenotypes of Obstructive Sleep Apnea

(1) Background: Sleep bruxism (SB) is a common sleep behavior. Obstructive sleep apnea (OSA) is a prevalent sleep-related breathing disorder with potential long-term major neurocognitive and cardiovascular sequelae. Although the co-occurrence of SB and OSA has been described previously, the exact relationship remains unclear. The present study aimed to evaluate the incidence of SB in different phenotypes of OSA. (2) Methods: The participants of this study were adult patients referred to the Department and Clinic of Internal Medicine, Occupational Diseases, Hypertension and Clinical Oncology at the Wroclaw Medical University. They underwent a single-night video polysomnography in a sleep laboratory. The data related to common OSA phenotypes were analyzed in two separate groups of patients: body position related (n = 94) and rapid eye movement (REM) related (n = 85). (3) Results: The obtained results showed that the incidence of SB and severe SB was higher for body position-related OSA phenotype (p < 0.05 for all comparisons). No statistically significant differences were observed for REM-related OSA phenotype (p > 0.05 for all comparisons). (4) Conclusions: Body position-related OSA phenotype seems to be associated with higher SB and severe SB incidence, but the relationship is not independent. However, in the light of the unclear relationship between SB and sleep-disordered breathing, the topic needs further study.

A Systematic Review of Sleep–Wake Disorder Diagnostic Criteria Reliability Studies

The aim of this article is to provide a systematic review of reliability studies of the sleep–wake disorder diagnostic criteria of the international classifications used in sleep medicine. Electronic databases (ubMed (1946–2021) and Web of Science (—2021)) were searched up to December 2021 for studies computing the Cohen’s kappa coefficient of diagnostic criteria for the main sleep–wake disorder categories described in the principal classifications. Cohen’s kappa coefficients were extracted for each main sleep–wake disorder category, for each classification subtype, and for the different types of methods used to test the degree of agreement about a diagnosis. The database search identified 383 studies. Fifteen studies were analyzed in this systematic review. Insomnia disorder (10/15) and parasomnia disorder (7/15) diagnostic criteria were the most studied. The reliability of all sleep–wake disorders presented a Cohen’s kappa with substantial agreement (Cohen’s kappa mean = 0.66). The two main reliability methods identified were “test–retest reliability” (11/15), principally used for International Classification of Sleep Disorders (ICSD), and “joint interrater reliability” (4/15), principally used for Diagnostic and Statistical Manual of Mental Disorders (DSM) subtype diagnostic criteria, in particularl, the DSM-5. The implications in terms of the design of the methods used to test the degree of agreement about a diagnosis in sleep medicine are discussed.

Associated factors of primary snoring and obstructive sleep apnea in patients with sleep bruxism: a questionnaire study

Background

By being aware of the associated factors of primary snoring (PS) and obstructive sleep apnoea (OSA) in sleep bruxism (SB) patients, dentists may contribute to the screening and early recognition of SB patients with PS or OSA.

Objective

To identify the associated factors of PS and OSA from questionnaire‐based data in SB patients.

Methods

A total of 968 self‐reported SB patients (31.6% men; median age 44.5 years) were retrospectively enrolled. Self‐reported sleep‐related breathing status (viz., no sleep‐related breathing condition, PS and OSA) was the dependent variable. Independent variables were questionnaire‐based data on demographics, lifestyle, psychological status, pain and sleep.

Results

For PS, no statistically significant associated factor was identified in analyses. For OSA, increased age (OR = 1.04 [1.03–1.06]), male gender (OR = 3.33 [2.17–5.00]), daily alcohol consumption (OR = 1.96 [1.18–3.33]), depression (OR = 1.10 [1.06–1.14]), daytime sleepiness (OR = 2.94 [1.85–4.76]) and high risk of gastroesophageal reflux disease (GERD; OR = 2.63 [1.52–4.76]) were found to be significant risk factors, while high risk of temporomandibular disorder (TMD) pain (OR = 0.51 [0.30–0.86]) and chronic pain (OR = 0.73 [0.59–0.90]) were significant protective factors. These results were confirmed in the subsequent network analysis.

Conclusion

Within the limitations of this study, no associated factor is identified for PS. For OSA, dentists should keep in mind that increased age, male gender, daily alcohol consumption, depression, daytime sleepiness and high GERD risk are associated with increased OSA risk in SB patients, while high TMD‐pain risk and chronic pain are associated with decreased OSA risk in this population.

The Effect of Severity of Obstructive Sleep Apnea on Sleep Bruxism in Respiratory Polygraphy Study

Obstructive sleep apnea (OSA) and sleep bruxism (SB) may appear concomitantly. Data on the relationship between OSA and SB are limited. It was shown that in a population with an increased risk of OSA, OSA was dependently correlated with SB on the degree of OSA severity only in mild and moderate cases of OSA. We aimed to confirm this relationship and affecting factors in a group of dental office patients in a prospective, observational study. Adult patients (n = 119) were evaluated using respiratory polygraphy. The risk of OSA was assessed using a STOP-Bang questionnaire (SBQ). The episodes of bruxism and respiratory events were scored according to the standards of the American Academy of Sleep Medicine. The prevalence of OSA and SB was found to be 63.02% and 41.17%, respectively. The bruxism episode index (BEI) was increased in the group with a higher risk of OSA (SBQ ≥ 3) compared to the group with a lower risk of OSA (3.49 ± 3.63 vs. 2.27 ± 2.50, p = 0.03). The sensitivity and specificity of the SBQ were not sufficient to predict SB. A positive linear correlation between AHI and BEI in the group with AHI < 23/h was found. The study confirmed that OSA was associated with SB in the group of patients with OSA and/or SB risk. The relationship between OSA and SB depended on the degree of severity of OSA and occurred in mild and moderate cases of OSA.

Polysomnographic Evaluation of Sleep Bruxism Intensity and Sleep Architecture in Nonapneic Hypertensives: A Prospective, Observational Study

Sleep bruxism (SB) is a repetitive jaw muscle activity characterized by clenching or grinding of the teeth, which is classified under sleep-related movement disorders in the International Classification of Sleep Disorders—Third Edition. Because the potential common pathomechanism of SB and arterial hypertension is the activation of the sympathetic system as well as an increase in inflammatory factors, we aimed to examine the intensity of SB and the sleep architecture among patients with arterial hypertension. The study included a total of 91 Caucasian adult patients, among whom 31 had arterial hypertension diagnosed according to the current European Society of Cardiology/European Society of Hypertension (ESC/EHS) hypertension guidelines. The control group consisted of 61 normotensive patients. Patients with obstructive sleep apnea were excluded. A single full-night polysomnographic examination was conducted in the Sleep Laboratory, and then the results were analyzed based on the guidelines of the American Academy of Sleep Medicine. Bruxism episode index (BEI) was higher in the hypertensive group compared to normotensives. The groups also showed statistically significant differences in polysomnographic sleep indexes. Similar to BEI, arousal index, apnea–hypopnea index, and snoring were higher in hypertensives compared to normotensives. On the other hand, the mean and minimal oxygen saturation were lower in hypertensives compared to normotensives. A statistically significant positive correlation was observed between oxygen desaturation index and BEI in the hypertensive group, whereas this correlation was not statistically significant in the case of normotensives. In summary, nonapneic hypertensives had higher SB intensity, altered sleep architecture, decreased mean oxygen saturation, and increased snoring compared to normotensives. The results suggest that dental screening is necessary for patients with arterial hypertension, especially those presenting with the symptoms of SB.

Assessment of Telomerase Reverse Transcriptase Single Nucleotide Polymorphism in Sleep Bruxism

Introduction: Sleep bruxism (SB) is a widespread masticatory muscle activity during sleep and affects approximately 13.2% of the general population. Telomerase reverse transcriptase (TERT) plays a role in preventing the shortening of the telomere. This prospective, observational study aimed to investigate the relationship between single nucleotide polymorphism (SNP) of TERT and the severity of SB and to identify the independent risk factors for SB. Methods: A total of 112 patients were diagnosed by performing one-night polysomnography based on the guidelines of the American Academy of Sleep Medicine. TERT SNP was detected by real-time quantitative polymerase chain reaction (qPCR). Results: Statistical analysis showed the lack of relationship between the rs2853669 polymorphism of TERT and severity of SB (p > 0.05). However, the study showed that patients with allele T in the 2736100 polymorphism of TERT had a lower score on the phasic bruxism episode index (BEI). Based on the receiver operating characteristic (ROC) curve, the value of phasic BEI was 0.8 for the differential prediction for the presence of allele T in the locus. The sensitivity and specificity were 0.328 and 0.893, respectively. The regression analysis showed that lack of TERT rs2736100 T allele, male gender, and arterial hypertension are the risk factors for the higher value of phasic BEI. Conclusion: The SNP of the TERT gene affects phasic SB intensity. The absence of TERT rs2736100 T allele, male sex, and arterial hypertension are independent risk factors for phasic SB.

Lower serotonin levels in severe sleep bruxism and its association with sleep, heart rate, and body mass index

BACKGROUND

Sleep bruxism (SB) is a complex behaviour that seems to be associated with the serotoninergic pathway.

OBJECTIVES

This exploratory research aimed to evaluate the levels of serotonin in individuals with sleep bruxism diagnosed by video polysomnography. The study also evaluated whether the levels of serotonin were associated with body mass index, heart rate, and sleep parameters.

METHODS

The study participants were adults hospitalised in the Department and Clinic of Internal Medicine, Occupational Diseases, Hypertension and Clinical Oncology at the Wroclaw Medical University. They underwent a single-night video polysomnography during which sleep and SB parameters and heart rate were evaluated. Additionally, body mass index and blood serotonin levels were evaluated for each patient.

RESULTS

A total of 105 patients were included in this study (80 women and 25 men). All the patients were Caucasians aged 18-63 years, with a mean age ± (standard deviation) of 33.43± 10.8 years. Seventy-five patients (71.43%) presented sleep bruxism (bruxism episodes index ≥2) and 30 (28.57%) did not. Fifty patients (47.62%) presented severe sleep bruxism (bruxism episodes index >4). The results showed that lower blood serotonin levels were associated with severe sleep bruxism; increased bruxism episodes index, rapid eye movement sleep, and body mass index; and decreased maximal pulse.

CONCLUSION

Severe sleep bruxism and the associated phenomena seem to co-occur with lower blood serotonin levels. The study supports the hypothesis on the relationship between the serotoninergic pathway and sleep bruxism.

Is sleep bruxism related to the levels of enzymes involved in the serotonin synthesis pathway?

OBJECTIVES

This exploratory research aimed to evaluate the levels of tryptophan hydroxylase 1 (TPH1) and aromatic l-amino acid decarboxylase (DDC), which play an important role in the serotonin synthesis pathway, in individuals with sleep bruxism (SB) diagnosed using audio-video polysomnography (vPSG) and compare them with that of individuals not presenting with SB.

MATERIALS AND METHODS

The study included adult patients hospitalized in the Department and Clinic of Internal Medicine, Occupational Diseases, Hypertension and Clinical Oncology at the Wroclaw Medical University. The participants underwent a single-night vPSG for the evaluation of the SB parameters. Peripheral blood samples were also collected from them for estimating the serum levels of TPH1 and DDC.

RESULTS

A total of 105 patients (80 women and 25 men) were included in the study. All the patients were Caucasians and aged 18-63 years (mean age: 33.43 ± 10.8 years). Seventy-five patients (71.43%) presented with SB, of which 50 (47.62%) had severe SB, while the remaining 30 patients (28.57%) did not. No statistically significant differences in TPH1 and DDC levels were observed between the individuals with SB and without SB. A significant negative correlation was found between tonic SB episodes and DDC levels (p = 0.0012). Other correlations between the SB parameters and the levels of the studied enzymes were statistically insignificant (p > 0.05 for all comparisons).

CONCLUSIONS

The levels of the enzymes that are crucial for serotonin synthesis (TPH1 and DDC) did not seem to influence SB.

CLINICAL RELEVANCE

This study provides important insights for further research on the relationship between the serotonin pathway and SB, which should take into account not only the process of serotonin synthesis but also the effect of serotonin-dependent neurotransmission on SB.

Sleep stage-dependent changes in tonic masseter and cortical activities in young subjects with primary sleep bruxism

STUDY OBJECTIVES

The present study investigated the hypothesis that subjects with primary sleep bruxism (SB) exhibit masseter and cortical hyperactivities during quiet sleep periods that are associated with a high frequency of rhythmic masticatory muscle activity (RMMA).

METHODS

Fifteen SB and ten control participants underwent polysomnographic recordings. The frequencies of oromotor events and arousals and the percentage of arousals with oromotor events were assessed. Masseter muscle tone during sleep was quantified using a cluster analysis. Electroencephalography power and heart rate variability were quantified and then compared between the two groups and among sleep stages.

RESULTS

The frequency of RMMA and percentage of arousals with RMMA were significantly higher in SB subjects than in controls in all stages, while these variables for non-rhythmic oromotor events did not significantly differ between the groups. In SB subjects, the frequency of RMMA was the highest in stage N1 and the lowest in stages N3 and R, while the percentage of arousals with RMMA was higher in stage N3 than stages N1 and R. The cluster analysis classified masseter activity during sleep into two clusters for masseter tone and contractions. Masseter muscle tone showed typical stage-dependent changes in both groups, but did not significantly differ between the groups. Furthermore, no significant differences were observed in electroencephalography power or heart rate variability between the groups.

CONCLUSION

Young SB subjects exhibited sleep stage-dependent increases in the responsiveness of RMMA to transient arousals, but did not show masseter or cortical hyperactivity during sleep.

Identifying predictive factors for sleep bruxism severity using clinical and polysomnographic parameters: a principal component analysis

STUDY OBJECTIVES

The aim was to identify predictive factors for sleep bruxism (SB) severity among polysomnographic parameters, salivary cortisol levels, temporomandibular disorders, age, and sex.

METHODS

Young adults (19-30 years) were screened for self-/roommate reports of teeth grinding/clenching during sleep associated with clinical signs of tooth wear. Individuals positive for both conditions were administered a polysomnographic exam to provide a definite diagnosis of SB (n = 28). Healthy participants without SB signs/symptoms were also included (n = 15). The Research Diagnostic Criteria for Temporomandibular Disorders was applied to determine functional, muscular, and articular domains of the Temporomandibular Index. Cortisol awakening levels were measured in saliva. Principal component analysis was used to extract the latent components emerging from polysomnographic results, and 2 regression models were adjusted to predict the number and duration of bruxism episodes.

RESULTS

Principal component analysis resulted in 4 components-C1: %N1, total sleep time, sleep efficiency, arousals/microarousals; C2: %N2, %N3; C3: periodic limb movements and apneas; C4: %REM and REM latency. The number of SB episodes/h was predicted by increasing muscular scores and C2 (decrease in %N2 and increase in %N3) (adjusted R² = 45%; P =.001). The total time of SB episodes was predicted by decreased articular and increased functional scores, age, and female sex (adjusted R² = 36%; P = 0.010). Salivary cortisol levels were not associated with SB severity and did not differ between groups.

CONCLUSIONS

The findings showed that SB severity was predicted by muscular and functional scores, female sex, and distinct polysomnographic patterns, contributing to the deeper knowledge of the underlying pathophysiology of SB severity; additionally, the findings can help to formulate health approaches that are specific to the patient and will better assist in treating this condition.

Research routes on improved sleep bruxism metrics: Toward a standardised approach

A recent report from the European Sleep Research Society's task force "Beyond AHI" discussed an issue that has been a long-term subject of debate - what are the best metrics for obstructive sleep apnoea (OSA) diagnosis and treatment outcome assessments? In a similar way, sleep bruxism (SB) metrics have also been a recurrent issue for >30 years and there is still uncertainty in dentistry regarding their optimisation and clinical relevance. SB can occur alone or with comorbidities such as OSA, gastroesophageal reflux disorder, insomnia, headache, orofacial pain, periodic limb movement, rapid eye movement behaviour disorder, and sleep epilepsy. Classically, the diagnosis of SB is based on the patient's dental and medical history and clinical manifestations; electromyography is used in research and for complex cases. The emergence of new technologies, such as sensors and artificial intelligence, has opened new opportunities. The main objective of the present review is to stimulate the creation of a collaborative taskforce on SB metrics. Several examples are available in sleep medicine. The development of more homogenised metrics could improve the accuracy and refinement of SB assessment, while moving forward toward a personalised approach. It is time to develop SB metrics that are relevant to clinical outcomes and benefit patients who suffer from one or more possible negative consequences of SB.