Insomnia with objective short sleep duration in women with temporomandibular joint disorder: quantitative sensory testing, inflammation and clinical pain profiles

Effects of sleep and circadian rest-activity rhythms on daily pain severity in women with temporomandibular disorders

ABSTRACT

Although a robust connection between sleep and pain is established, the extent to which circadian rest-activity rhythms contribute toward unique variations in pain, beyond what is elucidated by sleep, remains uncertain. Furthermore, it is largely unknown whether sleep and circadian rest-activity rhythms have interactive effects on daily pain severity. Using wrist actigraphy and daily pain diaries, data from 140 women with temporomandibular disorders and insomnia symptoms were analyzed over a 14-day period. Sleep duration and continuity were quantified by using total sleep time (TST) and wake after sleep onset (WASO), and circadian rest-activity rhythms were characterized with the Relative Amplitude (indicating strength/robustness of rest-activity rhythm) and Intradaily Variability metrics (representing rhythm fragmentation). Linear mixed-effects modeling revealed that both TST (b = -0.11, P = 0.006) and WASO (b = 0.18, P = 0.006) from the previous night, along with Relative Amplitude (b = -2.56, P = 0.001) from the past 24 hours, predicted next-day pain severity. Among the 4 interaction effects tested, both Intradaily Variability (b = 1.52, P = 0.034) and Relative Amplitude (b = -1.52, P = 0.003) moderated the relationship between WASO and next-day pain severity; on days characterized by less robustness (lower Relative Amplitude) or greater fragmentation (higher Intradaily Variability) in the circadian rest-activity rhythm, the positive association between previous night WASO and next-day pain severity intensified. These findings highlight the complex interplay among sleep, circadian rest-activity rhythms, and pain. While preliminary, our findings indicate that interventions aimed at improving both sleep and restoring circadian rhythms may provide enhanced benefits for managing chronic pain.

Retrospective Study on the Comparative Efficacy of Intra-Articular Injection and Photodynamic Therapy in the Treatment of TMD

Objective

To compare the effectiveness of intra-articular injection and photodynamic therapy (PDT) in the treatment of temporomandibular joint disorder (TMD).

Methods

A retrospective analysis was conducted on the clinical data of 91 TMD patients admitted to our hospital from August 2022 to February 2024. Patients were divided into the control group (n=45, treated with intra-articular injection) and the observation group (n=46, treated with PDT). Clinical outcomes, pain levels [Visual Analog Scale (VAS)], maximum mouth opening, masseter muscle pain threshold, Fricton Temporomandibular Joint Index (including Joints Number (JN), Joint Pain (JP), Muscle Masseter (MM), Disc Displacement Index (DI), Mandibular Position (MP), Pain Index (PI), and Clinical Measurement Index (CMI)], oral health [Oral Health Impact Profile-14 (OHIP-14)], and quality of life [Short Form-36 (SF-36)] were compared between the two groups.

Results

The total effective rate in the observation group (91.30%) was significantly higher than the control group (75.56%) (p<0.05). VAS scores showed significant group (F=5.487), time (F=8.356), and interaction effects (F=6.931) (p<0.05). Within-group comparisons showed a significant decrease in VAS scores 1 and 4 weeks after treatment (p<0.05), with the observation group showing lower VAS scores than the control group (p<0.05). After treatment, maximum mouth opening and masseter muscle pain threshold increased in both groups, with the observation group showing greater improvement (p<0.05). Fricton Temporomandibular Joint Index scores decreased significantly in both groups, with the observation group showing a more significant reduction (p<0.05). OHIP-14 scores decreased, and SF-36 scores increased in both groups, with the observation group showing greater improvement (p<0.05).

Conclusion

PDT is more effective than intra-articular injection in treating TMD. PDT further relieves pain, increases maximum mouth opening and masseter muscle pain threshold, reduces the Fricton index, and improves oral health and quality of life.

Differential pain perception among females with or without nonspecific chronic low back pain and comorbid insomnia: a quantitative sensory testing analysis

ABSTRACT

Sleep disturbance is a prevalent condition in individuals with chronic low back pain (CLBP). Despite a strong association between the 2 conditions, the potential mechanisms underlying the role of sleep disturbance in CLBP remain unclear. This case-control study aimed to examine pain perception among females with or without nonspecific CLBP and comorbid insomnia. One hundred females were recruited (mean age: 34.3 ± 11.4 years), with 25 individuals with concomitant CLBP and insomnia (CLBP+I), 25 with CLBP (CLBP+), 25 with insomnia (Insomnia+), and 25 healthy controls. All participants completed self-report questionnaires and quantitative sensory testing (QST). Our study found that CLBP+I exhibited lower mechanical pain and pressure pain thresholds (PPT) in both painful and nonpainful areas and impaired conditioned pain modulation (CPM) as compared to healthy controls. Similar findings were found in PPT at the back and CPM when compared to CLBP+. However, no significant differences were noted in thermal pain thresholds and temporal summation of pain across the 4 groups. Furthermore, CLBP+I and Insomnia+ displayed higher levels of functional disability, maladaptive beliefs, and negative mood than CLBP+ or healthy controls. There were significant increases in pain sensitivity to pressure stimuli, decreases in descending pain inhibitory effects, and higher levels of maladaptive psychological status in CLBP+I compared to CLBP+. These findings underscore the importance of incorporating sleep assessments as a routine practice in treating CLBP cases. Future studies are warranted to validate our findings in males, establish the diagnostic and prognostic value of QST, and probe the neurophysiological mechanisms in comorbid conditions.

The Association Between Insomnia and Temporomandibular Disorders in Orthodontic Patients

Objective

This cross-sectional study aimed to investigate the association between insomnia and the presence of temporomandibular disorders (TMD) and its subtypes in orthodontic patients.

Methods

A total of 648 adult orthodontic patients (158 males and 490 females, median age 26) were included and completed a questionnaire containing sociodemographic information, insomnia severity index (ISI), the five major temporomandibular disorder symptoms (5Ts) checklist, and self-reported sleep bruxism. Presence of insomnia and TMD of the included patients was determined according to the diagnostic criteria, and statistical analyses were conducted as appropriate to compare ISI-related scores between TMD and non-TMD participants. Further, multivariable regressions were performed to detect the potential correlation between insomnia and TMD in orthodontic patients.

Results

Orthodontic patients with TMD scored significantly higher in both the individual items and the total sum of ISI than those without TMD. More patients were bothered by insomnia in the TMD group than the non-TMD counterparts (26.6% vs 16.7%, p=0.003). After adjusting for confounding variables, insomnia was found to be significantly correlated with TMD in orthodontic patients (OR=1.677, 95% CI 1.128, 2.511). Subgroup analysis of TMD subtypes showed a significant positive association of insomnia with pain-related TMD (OR=2.007, 95% CI 1.331, 3.015).

Conclusion

Insomnia was associated with a higher prevalence of pain-related TMD rather than intra-articular TMD in orthodontic patients.

Sleep misperception in women with myofascial temporomandibular disorder

STUDY OBJECTIVES

Temporomandibular disorders (TMDs) were linked to poor sleep on the Pittsburgh Sleep Quality Index (PSQI), whereas polysomnography revealed no major sleep disturbances, implying sleep state misperception. This study investigates sleep state misperception in TMD and control participants; correlates sleep state misperception with objective short sleep duration (SSD), depression symptoms, daytime sleepiness, and orofacial pain; and compares objective SSD between the groups.

METHODS

General linear models were used to compare second-night polysomnography total sleep time, sleep latency, sleep efficiency (SE), and wake after sleep onset with homologous PSQI-derived variables in 124 women with myofascial TMD and 46 age and body mass index matched controls. PSQI variables were regressed onto objective SSD, depression symptoms, daytime sleepiness, and pain. Lastly, objective SSD was related to TMD presence.

RESULTS

Compared to controls, TMD cases misperceived SE (P = .02); depression symptoms explained PSQI-derived SE (P = .002) and mediated the effect of pain (P < .001). PSQI variables were unrelated to respective polysomnography measures or objective SSD, except a significant self-reported-objective correlation in SE among controls only (P = .002). Objective SSD was more frequent in TMD cases (P = .02, odds ratio = 2.95), but it was unrelated to depression symptoms, daytime sleepiness, or prepolysomnography pain.

CONCLUSIONS

The study demonstrates misperception of SE among TMD cases, which was accounted for by depression symptoms. Objective SSD nearly tripled in TMD cases; however, it was unrelated to PSQI variables, depression, daytime sleepiness, or pain, suggesting that sleep state misperception and objective SSD are 2 independent sleep features in TMD.

CITATION

Chan C, Dubrovsky B, Bouchard M, Tartter VC, Raphael KG. Sleep misperception in women with myofascial temporomandibular disorder. J Clin Sleep Med. 2025;21(1):55-64.

Association of night-time sleep and daytime napping with painful temporomandibular disorder

BACKGROUND

Painful temporomandibular disorder (TMD) is the common cause of chronic oro-facial pain, which may interfere with sleep. Previous studies have documented an association between sleep and TMD.

OBJECTIVES

This study aimed to further explore the association of night-time sleep and daytime napping with painful TMD.

METHODS

A total of 419 patients (aged 31.88 ± 11.54 years with women forming 85.4%) from a TMD/Orofacial Pain center were enrolled. Patients' sleep conditions were evaluated with the Pittsburgh Sleep Quality Index (PSQI) questionnaire, and information on night-time sleep duration, napping duration and napping frequency was interviewed. TMD was diagnosed according to the Diagnostic Criteria for TMD protocol and stratified into myalgia (muscle pain), arthralgia (joint pain) and combined (muscle and joint pain) subgroups. The severity of TMD was measured with the Fonseca Anamnestic Index (FAI) questionnaire. Restricted cubic spline (RCS) regression models were established to explore relationships between sleep and painful TMD subgroups.

RESULTS

Patients with poor sleep quality (PSQI≥6) had higher FAI scores (median 60, p < .001) and higher proportions of painful TMDs. The myalgia subgroup had higher PSQI scores (median 8, p < .001) than the arthralgia subgroup. The RCS models indicated a non-linear relationship between night-time sleep duration and myalgia (p < .001), which was not observed in arthralgia. However, there were no significant findings concerning napping and painful TMD subgroups.

CONCLUSION

This study found that the association between sleep and TMD is mainly related to painful TMD conditions, which are associated with night-time sleep duration.

Hematological biomarkers of systemic inflammation in predicting long-term treatment response of temporomandibular disorders

BACKGROUND

Chronic systemic inflammation has been proposed as the underlying mechanism of pain chronicity in several pain conditions. In spite of the growing evidence supporting the role of systemic inflammatory markers as a diagnostic tool, their role has not been analyzed in a well-defined group of temporomandibular disorders (TMD) patients until now. This study aimed to investigate the association between various clinical features and comorbidity levels of TMD in relation to hematological markers and seek its association with long-term treatment response.

METHODS

Clinical features and hematological indices including those for systemic inflammation were assessed in TMD patients (n = 154). Examinations were re-done after 6 months of conservative treatment. Patients were divided into pain improved and unimproved groups based on ≥ 2 numeric rating scale improvement in pain intensity at 6 months for final analysis.

RESULTS

The portion of patients with low lymphocyte-to-monocyte ratio (p = 0.026), total protein (p = 0.014), hemoglobin (p = 0.040), and mean corpuscular hemoglobin concentration (p = 0.042) values showed significant differences according to prognosis groups. Low hemoglobin levels were significantly associated with unfavorable response to long-term treatment (β = 1.706, p = 0.018). High pre-treatment pain intensity (β=-0.682, p < 0.001) and low Graded Chronic Pain Scale (β = 1.620, p = 0.002) could predict significant pain improvement with long-term treatment.

CONCLUSIONS

Hematologic assessment could be considered in addition to clinical examination to better determine long-term prognosis in TMD patients.

Elevated pain sensitivity is associated with reduced rapid eye movement (REM) sleep in females with comorbid temporomandibular disorder and insomnia

OBJECTIVE

Patients with chronic pain disorders, including Temporomandibular Disorders (TMDs) endorse high levels of sleep disturbances, frequently reporting reduced sleep quality. Despite this, little is known about the effect that daytime pain has on the microstructure and macro-architecture of sleep. Therefore, we aimed to examine the extent to which daytime pain sensitivity, measured using quantitative sensory testing (QST), is associated with objective sleep parameters the following night, including sleep architecture and power spectral density, in women with TMD.

METHODS

144 females with myalgia and arthralgia by examination using the Diagnostic criteria for TMD completed a comprehensive QST battery consisting of General Pain Sensitivity, Central Sensitization Index, and Masseter Pressure Pain Threshold assessments. Polysomnography was collected the same night to measure sleep architecture and calculate relative power in delta, theta, alpha, sigma, and beta power bands.

RESULTS

Central Sensitization (B = -3.069, P = .009), General Pain Sensitivity Indices (B = -3.069, P = .007), and Masseter Pain Pressure Threshold (B = 0.030, P = .008) were significantly associated with lower REM% both before and after controlling for covariates. Pain sensitivity measures were not significantly associated with relative power in any of the spectral bands nor with any other sleep architectural stages.

CONCLUSIONS

Our findings demonstrate that higher generalized pain sensitivity, masseter pain pressure threshold, as well as central sensitization were associated with a lower percentage of REM in participants with myofascial pain and arthralgia of the masticatory system. These findings provide an important step toward understanding the mechanistic underpinnings of how chronic pain interacts with sleep physiology.

Exploring the causal effects of sleep characteristics on TMD-related pain: a two-sample Mendelian randomization study

OBJECTIVES

The study was to explore the causal effects of sleep characteristics on temporomandibular disorder (TMD)-related pain using Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

Five sleep characteristics (short sleep, insomnia, chronotype, snoring, sleep apnea) were designated as exposure factors. Data were obtained from previous publicized genome-wide association studies and single nucleotide polymorphisms (SNPs) strongly associated with them were utilized as instrumental variables (IVs). TMD-related pain was designed as outcome variable and sourced from the FinnGens database. MR analysis was employed to explore the causal effects of the five sleep characteristics on TMD-related pain. The causal effect was analyzed using the inverse variance-weighted (IVW), weighted median, and MR-Egger methods. Subsequently, sensitivity analyses were conducted using Cochran's Q tests, funnel plots, leave-one-out analyses, and MR-Egger intercept tests.

RESULTS

A causal effect of short sleep on TMD-related pain was revealed by IVW (OR: 1.60, 95% CI: 1.06-2.41, P = 0.026). No causal relationship was identified between other sleep characteristics (insomnia, chronotype, snoring, sleep apnea) and TMD-related pain.

CONCLUSIONS

Our study suggests that short sleep may increase the risk of TMD-related pain, while there was no causal relationship between other sleep characteristics and TMD-related pain. Further studies are warranted to deepen and definitively clarify their relationship.

CLINICAL RELEVANCE

These findings reveal that the short sleep may be a risk factor of TMD-related pain and highlight the potential therapeutical effect of extending sleep time on alleviating TMD-related pain.

Sleep disorders and orofacial pain: insights for dental practice

In dental sleep medicine several sleep disorders commonly coexist with pain, contributing to complex clinical presentations which might affect the provision of appropriate and timely treatment. There are associations between sleep disorders and pain in general, as well as with specific orofacial pain conditions. As many as five of six patients with orofacial pain can present with sleep problems. The comorbidity of orofacial pain and sleep disorders overlays a complex web of altered neurobiological mechanisms that predispose to the chronification of orofacial pain. This review discusses the relationship between orofacial pain and sleep disorders and highlights their interactions and the neurobiological mechanisms underlying those relationships.

The Impact of Sleep Disturbances on Endogenous Pain Modulation: A Systematic Review and Meta-Analysis

The bidirectional relationship between sleep and pain problems has been extensively demonstrated but despite all the accumulating evidence, their shared mechanisms are currently not fully understood. This review examined the association between sleep disturbances, defined as a broad array of sleep-related outcomes (eg, poor quality, short duration, insomnia), and endogenous pain modulation (EPM) in healthy and clinical populations. Our search yielded 6,151 references, and 37 studies met the eligibility criteria. Qualitative results showed mixed findings regarding the association between sleep disturbances and temporal summation of pain (TSP) and conditioned pain modulation (CPM), with poor sleep more commonly associated with decreased pain inhibition in both populations. Quantitative results indicated that such associations were not statistically significant, neither in healthy populations when EPM outcomes were assessed for changes pre-/post-sleep intervention (TSP: .31 [95%CI: -.30 to .92]; P = .321; CPM: .40 [95%CI: -.06 to .85] P = .088) nor in clinical populations when such association was assessed via correlation (TSP: -.00 [95%CI: -.22 to .21] P = .970; CPM: .12 [95%CI: -.05 to .29]; P = .181). For studies that reported results by sex, meta-analysis showed that experimental sleep disturbances impaired pain inhibition in females (1.43 [95%CI: .98-1.88]; P < .001) but not in males (-.30 [95%CI: -2.69 to 1.60]; P = .760). Only one study investigating the association between sleep disturbances and offset analgesia was identified, while no studies assessing spatial summation of pain were found. Overall, this review provides a comprehensive overview of the association between sleep disturbances and EPM function, emphasizing the need for further investigation to clarify specific mechanisms and phenotypic subtypes. PERSPECTIVE: This review shines a light on the association between sleep disturbances and endogenous pain modulation function. Qualitatively, we found a frequent association between reduced sleep quality and impaired pain inhibition. However, quantitatively such an association was not corroborated. Sex-specific effects were observed, with females presenting sleep-related impaired pain inhibition but not males.

Dental sleep medicine education among undergraduate dental students in France

INTRODUCTION

Dental sleep medicine (DSM) is an emerging discipline that studies the oral and maxillofacial causes and consequences of sleep-related problems. DSM is of upmost importance given the major medical challenge it represents. Therefore, to verify whether the future generation of dentists would be ready to face this challenge, the main objective of this study was to assess the degree of involvement of the French dental schools in teaching DSM at the undergraduate level.

MATERIALS AND METHODS

All 16 dental schools in France were asked to participate in the study by answering to an online survey concerning the DSM curriculum during the 2018-2019 academic year. The survey was addressed to the head of the dental school and/or to relevant course coordinators and contained 10 questions related to the type, content and amount of DSM teaching to undergraduate dental students.

RESULTS

Nine of the 16 (56.2%) French dental schools responded to the questionnaire. All these nine reported the inclusion of DSM in their undergraduate curriculum. The total average hours dedicated to teaching DSM was 5.6 h (SD 4.2; range 1-15 h). Seven of the 9 dental schools spent most of their DSM curriculum teaching time in the fifth year. All of them reviewed obstructive sleep apnoea and sleep-related bruxism and covered some topics related to therapies for sleep-related breathing disorders, such as the use of oral appliance.

CONCLUSION

The results of this survey showed that, although the average hourly volume is relatively high, the DSM teaching in French dental schools appeared to be non-standardised, heterogeneous and often lacunar. It is therefore essential to develop a common curriculum and implement it in all dental schools to provide undergraduate students a comprehensive and updated teaching in DSM.

Effects of physical activity levels on characteristic pain in temporomandibular dysfunctions: a cross-sectional study

BACKGROUND

Physical activity is known to influence the symptoms of a variety of pain disorders including fibromyalgia and osteoarthritis although the underlying mechanism is not fully understood. In spite of the high prevalence of temporomandibular disorders (TMD), no previous study has objectively evaluated the relationship between TMD and general physical activity. This study aims to investigate the influence of physical activity on pain and disability from TMD, considering various confounders including sleep, systemic inflammation, psychosocial disturbances, and widespread pain.

METHODS

This observational cross-sectional study is based on consecutive samples of 100 TMD patients (22 with high pain disability and 78 with low pain disability level). Physical activity levels were assessed with actigraph. Level of pain and disability were evaluated using the Graded Chronic Pain Scale. Hematologic examinations including inflammatory biomarkers were assessed and comorbidities were investigated with validated questionnaires. Differences were analyzed according to disability level.

RESULTS

Patients with high disability level spent significantly more time doing both moderate (p = 0.033) and vigorous (p = 0.039) level physical activity. Light physical activity, on the other hand, was associated with low disability but the difference did not reach statistical significance. Time spent in light physical activity was significantly associated with high levels of pain and disability (p = 0.026, β = -0.001) and time spent in vigorous physical activity had significant predictive power (cutoff value 2.5 min per week, AUC 0.643, p = 0.041). Scores of the Jaw Function Limitation Score-20 (p = 0.001), present McGill Pain Score (p = 0.010), and number of people potentially diagnosed with fibromyalgia (p = 0.033) were significantly higher in the high disability group.

CONCLUSIONS

Moderate or vigorous physical activity is associated with worse TMD symptoms while light physical activity may be beneficial. Further research related to the amount and frequency of physical activity is necessary to establish clinical guidelines for TMD.

TRIAL REGISTRATION

clinical trial registration of the Clinical Research Information Service of Republic of Korea (number KCT0007107).

Sleep-EEG in comorbid pain and insomnia: implications for the treatment of pain disorders

INTRODUCTION

Patients with chronic pain experience a high prevalence of comorbid insomnia, which is associated with functional impairment. Recent advances in sleep electroencephalography (sleep-EEG) may clarify the mechanisms that link sleep and chronic pain. In this clinical update, we outline current advancements in sleep-EEG assessments for pain and provide research recommendations.

RESULTS

Promising preliminary work suggests that sleep-EEG spectral bands, particularly beta, gamma, alpha, and delta power, may create candidate neurophysiological signatures of pain, and macro-architectural parameters (e.g., total sleep time, arousals, and sleep continuity) may facilitate EEG-derived sleep phenotyping and may enable future stratification in the treatment of pain.

CONCLUSION

Integration of measures obtained through sleep-EEG represent feasible and scalable approaches that could be adopted in the future. We provide research recommendations to progress the field towards a deeper understanding of their utility and potential future applications in clinical practice.

Insomnia nosology: a systematic review and critical appraisal of historical diagnostic categories and current phenotypes

Insomnia nosology has significantly evolved since the Diagnostic and Statistical Manual (DSM)-III-R first distinguished between 'primary' and 'secondary' insomnia. Prior International Classification of Sleep Disorders (ICSD) nosology 'split' diagnostic phenotypes to address insomnia's heterogeneity and the DSM nosology 'lumped' them into primary insomnia, while both systems assumed causality for insomnia secondary to health conditions. In this systematic review, we discuss the historical phenotypes in prior insomnia nosology, present findings for currently proposed insomnia phenotypes based on more robust approaches, and critically appraise the most relevant ones. Electronic databases PsychINFO, PubMED, Web of Science, and references of eligible articles, were accessed to find diagnostic manuals, literature on insomnia phenotypes, including systematic reviews or meta-analysis, and assessments of the reliability or validity of insomnia diagnoses, identifying 184 articles. The data show that previous insomnia diagnoses lacked reliability and validity, leading current DSM-5-TR and ICSD-3 nosology to 'lump' phenotypes into a single diagnosis comorbid with health conditions. However, at least two new, robust insomnia phenotyping approaches were identified. One approach is multidimensional-multimethod and provides evidence for self-reported insomnia with objective short versus normal sleep duration linked to clinically relevant outcomes, while the other is multidimensional and provides evidence for two to five clusters (phenotypes) based on self-reported trait, state, and/or life-history data. Some approaches still need replication to better support whether their findings identify true phenotypes or simply different patterns of symptomatology. Regardless, these phenotyping efforts aim at improving insomnia nosology both as a classification system and as a mechanism to guide treatment.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2022 dental literature to briefly touch on several topics of interest to modern restorative dentistry. Each committee member brings discipline-specific expertise in their subject areas that include (in order of the appearance in this report): prosthodontics; periodontics, alveolar bone, and peri-implant tissues; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence the daily dental treatment decisions of the reader with an emphasis on innovations, new materials and processes, and future trends in dentistry. With the tremendous volume of literature published daily in dentistry and related disciplines, this review cannot be comprehensive. Instead, its purpose is to update interested readers and provide valuable resource material for those willing to subsequently pursue greater detail on their own. Our intent remains to assist colleagues in navigating the tremendous volume of newly minted information produced annually. Finally, we hope that readers find this work helpful in managing patients.

Systemic Factors in Temporomandibular Disorder Pain

The science of temporomandibular disorder (TMD) pain and its management has gone through significant changes during the last several decades. The authors strongly feel that the effect of systemic factors influencing TMD pain has been largely overlooked and poorly accounted for, even in established pain-management programs and protocols. The hope is that this article will act as a wake-up call for the pain management community to consider the importance of adequate knowledge of the systemic factors that affect the experience of TMD pain by the patient.

Temporomandibular Joint Disorder Comorbidities

Comorbidity is a distinct additional condition that either existed or exists during the clinical course of a patient afflicted by the condition/entity in question. The clinician attempting to manage temporomandibular joint disorder (TMD) and TMD pain must realize that recognition and management of the comorbidities are essential to the successful management of the same with optimal pain control. When TMD presents with multiple comorbidities, the task for the clinician becomes more complex. It is the hope of the authors that this condensed version of TMD-associated comorbidities acts as a primer for understanding the significance of the same in pain management.

Nocturnal Delta Power is Associated With Lower Next-Day Pain But Not Pain Catastrophizing: Results From a Cohort of Female Participants With Temporomandibular Joint Pain

Existing data demonstrate reduced delta power during sleep in patients with depression and chronic pain. However, there has been little examination of the relationship between delta power and pain-reports, or pain-catastrophizing. We recruited female participants (n = 111) with insomnia and temporomandibular disorder, and measured nocturnal and daytime measures of pain and pain catastrophizing, and calculated relative nocturnal delta (0.5-4 Hz) power during sleep. We fit linear regression models, and further examined the moderating effect of depressive symptom severity. Lower relative delta power across the whole night was significantly associated with greater nocturnal pain (B = -20.276, P = .025, R2 = 0.214). Lower relative delta power during the first-third of the night, was associated with greater nocturnal pain (B = -17.807, p = 0.019, R2 = 0.217), next-day pain (B = 13.876, P = .039, R2 = 0.195), and next-morning pain (B = -15.751, P = .022, R2 = 0.198). Lower relative delta power during the final-third of the night was significantly associated with greater nocturnal (B = -17.602, P = .029, R2 = 0.207) and next-morning pain (3rd: B = -14.943, P = .042, R2 = 0.187). Depressive symptom severity did not moderate these relationships. Delta power was not significantly associated with nocturnal or daytime pain catastrophizing. These findings demonstrate that greater relative delta power during sleep is associated with lower nocturnal and next-day pain in patients with temporomandibular disorder. This data may guide the use of sleep interventions in clinical pain populations, with the aim of improving pain outcomes. PERSPECTIVE: This article presents data demonstrating an association between increased nocturnal delta power and reduced next-day pain. These findings may help promote interventions which aim to increase nocturnal delta power in clinical pain populations, with the goal of improving pain outcomes.

The complexities of the sleep-pain relationship in adolescents: A critical review

Chronic pain is a common and disabling condition in adolescents. Disturbed sleep is associated with many detrimental effects in adolescents with acute and chronic pain. While sleep and pain are known to share a reciprocal relationship, the sleep-pain relationship in adolescence warrants further contextualization within normally occurring maturation of several biopsychological processes. Since sleep and pain disorders begin to emerge in early adolescence and are often comorbid, there is a need for a comprehensive picture of their interrelation especially related to temporal relationships and mechanistic drivers. While existing reviews provide a solid foundation for the interaction between disturbed sleep and pain in youth, we will extend this review by highlighting current methodological challenges for both sleep and pain assessments, exploring the recent evidence for directionality in the sleep-pain relationship, reviewing potential mechanisms and factors underlying the relationship, and providing direction for future investigations. We will also highlight the potential role of digital technologies in advancing the understanding of the sleep and pain relationship. Ultimately, we anticipate this information will facilitate further research and inform the management of pain and poor sleep, which will ultimately improve the quality of life in adolescents and reduce the risk of pain persisting into adulthood.

The influence of sleep on fear extinction in trauma-related disorders

In Posttraumatic Stress Disorder (PTSD), fear and anxiety become dysregulated following psychologically traumatic events. Regulation of fear and anxiety involves both high-level cognitive processes such as cognitive reattribution and low-level, partially automatic memory processes such as fear extinction, safety learning and habituation. These latter processes are believed to be deficient in PTSD. While insomnia and nightmares are characteristic symptoms of existing PTSD, abundant recent evidence suggests that sleep disruption prior to and acute sleep disturbance following traumatic events both can predispose an individual to develop PTSD. Sleep promotes consolidation in multiple memory systems and is believed to also do so for low-level emotion-regulatory memory processes. Consequently sleep disruption may contribute to the etiology of PTSD by interfering with consolidation in low-level emotion-regulatory memory systems. During the first weeks following a traumatic event, when in the course of everyday life resilient individuals begin to acquire and consolidate these low-level emotion-regulatory memories, those who will develop PTSD symptoms may fail to do so. This deficit may, in part, result from alterations of sleep that interfere with their consolidation, such as REM fragmentation, that have also been found to presage later PTSD symptoms. Here, sleep disruption in PTSD as well as fear extinction, safety learning and habituation and their known alterations in PTSD are first briefly reviewed. Then neural processes that occur during the early post-trauma period that might impede low-level emotion regulatory processes through alterations of sleep quality and physiology will be considered. Lastly, recent neuroimaging evidence from a fear conditioning and extinction paradigm in patient groups and their controls will be considered along with one possible neural process that may contribute to a vulnerability to PTSD following trauma.

Does risk of obstructive sleep apnea have interaction with chronic facial pain?

Objectives

The main purpose of the present study was to investigate the associations between the risk of obstructive sleep apnea (OSA) and chronic orofacial pain in a nationally representative sample of the Korean population.

Materials and Methods

Data from the 8th wave Korean national health and nutrition examination survey, which was conducted from 2019 to 2020 were analyzed. This study included 5,780 Koreans (2,503 males, 3,277 females) over 40 years of age. The presence of subjective chronic facial pain lasting more than 3 months was evaluated based on a self-reported questionnaire. The risk of OSA was determined using the STOP-BANG questionnaire. Data related to anthropometric and sociodemographic factors; diagnostic history of hypertension, depression, and OSA; level of health-related quality of life and stress awareness; health-related behaviors, including smoking and alcohol drinking; and sleep duration were collected. The participants were classified into two groups according to the presence of chronic facial pain.

Results

The level of health-related quality of life and stress awareness showed significant differences between the two groups. The sleep duration on weekends also presented significant differences. No significant differences were observed in the presence of snoring and observed apnea, while participants with chronic facial pain showed significantly higher levels of tiredness between the groups. The risk of OSA evaluated by STOP-BANG questionnaire showed significant differences between groups; however, the risk of OSA seemed to be higher in participants without chronic facial pain.

Conclusion

The participants with chronic facial pain demonstrated decreased sleep duration, lower health-related quality of life, and increased stress and tiredness. Even though, the role of OSA in the development of chronic facial pain was inconclusive from the study, it is possible that ethnicity play a role in relationship between OSA and chronic facial pain.

Associations between obstructive sleep apnea and painful temporomandibular disorder: a systematic review

The relationship between obstructive sleep apnea (OSA) and diverse types of pain conditions have been proposed. However, no consensus on the relationship between OSA and painful temporomandibular disorders (TMDs) has been established. Therefore, this systematic review has been conducted to review the existing literatures and provide comprehensive synthesis of such literatures about OSA and painful TMDs using the evidence-based methodology. A literature search was conducted using two electronic databases, Scopus, and PubMed. Risk of bias was assessed using the risk-ofbias assessment tool for non-randomized study version 2.0. A total of 158 articles were screened from the initial search and eventually, 5 articles were included in this systematic review. One study adopted both the longitudinal prospective cohort and case-control designs and other 4 articles adopted the cross-sectional design. Two studies employed polysomnography (PSG) for the diagnosis of OSA and mentioned the results from the PSG. All crosssectional studies demonstrated higher OSA prevalence among patients with TMD, and one cohort study suggested OSA as a risk factor for TMD. OSA appears to have potential influences on the development of TMD; however, the role of TMD in the development of OSA remains to be unknown owing to the lack of high-quality evidences.

Associations between insomnia and central sensitization in cancer survivors undergoing opioid therapy for chronic cancer pain: A STROBE-compliant prospective cohort study

Several risk factors for insomnia in cancer patients have been recognized, including chronic pain and treatment with opioid. Although associations between insomnia and central sensitization were previously reported in patients with chronic non-cancer pain, those have not been elucidated among cancer survivors undergoing opioid therapy for chronic cancer pain. To investigate the associations between insomnia and central sensitization among cancer survivors undergoing opioid therapy for chronic cancer pain, consecutive patients undergoing chemotherapy with chronic cancer pain under opioid therapy on an outpatient basis were enrolled from September 2019 to August 2020 and answered questions from the Athens Insomnia Scale (AIS) for assessing insomnia. Pain characteristics, including pain intensity, neuropathic pain, central sensitization assessed using the central sensitization inventory (CSI), opioid use disorder, and pain-related psychological symptoms were also examined. Uni- and multivariate regression analyses were performed to elucidate correlations between the AIS score and these pain characteristics. Of 44 enrolled patients, 20 patients completed to answer all questions. Insomnia was identified in 9 patients (45%). Although AIS scores showed no significant associations with pain intensity, neuropathic pain, opioid use disorder, or psychological symptoms, multivariate regression analysis revealed that CSI scores showed a positive relationship with AIS scores (P = .004). Discrimination was assessed using linear regression analysis which confirmed a significant association between the AIS and CSI scores (P = .002). Insomnia appears to be associated with central sensitization in cancer survivors with chronic cancer pain under opioid therapy.

Nightmare disorder and low back pain in veterans: cross-sectional association and effect over time

Low back pain (LBP) disproportionately impacts US military veterans compared with nonveterans. Although the effect of psychological conditions on LBP is regularly studied, there is little published to date investigating nightmare disorder (NMD) and LBP. The purpose of this study was to (1) investigate whether an association exists between NMD and LBP and (2) estimate the effect of NMD diagnosis on time to LBP. We used a retrospective cohort design with oversampling of those with NMD from the Veterans Health Administration (n = 15 983). We used logistic regression to assess for a cross-sectional association between NMD and LBP and survival analysis to estimate the effect of NMD on time to LBP, up to 60-month follow-up, conditioning on age, sex, race, index year, Charlson Comorbidity Index, depression, anxiety, insomnia, combat exposure, and prisoner of war history to address confounding. Odds ratios (with 95% confidence intervals [CIs]) indicated a cross-sectional association of 1.35 (1.13 to 1.60) and 1.21 (1.02 to 1.42) for NMD and LBP within 6 months and 12 months pre- or post-NMD diagnosis, respectively. Hazard ratios (HRs) indicated the effect of NMD on time to LBP that was time-dependent-HR (with 95% CIs) 1.27 (1.02 to 1.59), 1.23 (1.03 to 1.48), 1.19 (1.01 to 1.40), and 1.10 (0.94 to 1.29) in the first 3, 6, 9, and 12 months post-diagnosis, respectively-approximating the null (1.00) at >12 months. The estimated effect of NMD on LBP suggests that improved screening for NMD among veterans may help clinicians and researchers predict (or intervene to reduce) risk of future back pain.