Sleep, Positive Affect, and Circulating Interleukin-6 in Women With Temporomandibular Joint Disorder.

OBJECTIVE: Systemic inflammation is commonly observed in idiopathic chronic pain conditions, including temporomandibular joint disorder (TMD). Trait positive affect (PA) is associated with lower inflammation in healthy controls, but those effects may be threatened by poor sleep. The associations between PA with proinflammatory cytokine activity and potential moderation by sleep in chronic pain are not known. We thus investigated the association between PA and circulating interleukin-6 (IL-6) and moderation of that association by sleep in a sample of women with TMD and sleep difficulties. METHODS: Participants (n = 110) completed the insomnia severity index and provided blood samples at five intervals throughout an evoked pain testing session. They then completed a 14-day diary assessing sleep and affect, along with wrist actigraphy. RESULTS: There was not a significant main effect of PA on resting or pain-evoked IL-6 (b = 0.04, p = .33). Diary total sleep time (b = -0.002, p = .008), sleep efficiency (b = -0.01, p = .005), sleep onset latency (b = 0.006, p = .010), and wake after sleep onset (b = 0.003, p = .033) interacted with PA to predict IL-6, such that PA inversely predicted IL-6 at higher levels of total sleep time and sleep efficiency and at lower levels of sleep onset latency and wake after sleep onset. Surprisingly, when sleep was poor, PA predicted greater IL-6. CONCLUSIONS: The potential salutary effects of PA on resting IL-6 erode when sleep is poor, underscoring the importance of considering sleep in conceptual and intervention models of TMD.

Pain catastrophizing may moderate the association between pain and secondary hyperalgesia.

Catastrophizing, a persistent negative mental set characterized by helplessness, rumination, and magnification of pain sensations, has a potent effect on pain report and clinical outcomes. Previous studies have documented an association between cognitive factors and central sensitization. The current analysis sought to test the potential modulating effect of pain catastrophizing on the association between capsaicin pain and the region of secondary hyperalgesia. Thirty-eight healthy individuals (50% women, mean age = 25.7, SD = 5.3) completed the Pain Catastrophizing Scale (PCS), then underwent topical application of 10% capsaicin, which was covered by a thermode maintained at 40°C for 90-min. Following removal of the capsaicin, the region of secondary hyperalgesia was determined. Hayes' PROCESS macro was employed to examine catastrophizing's potential moderating effect, which did not reveal a significant association between capsaicin pain ratings and the region of secondary hyperalgesia (ß = 15.1, p = .06). Though PCS was not associated with area of secondary hyperalgesia (ß = 23.9, p = .29), a significant interaction was present between PCS and capsaicin pain ratings (ß = 3.7, p = .0004). Specifically, those endorsing higher catastrophizing levels and higher pain ratings experienced the greatest areas of secondary hyperalgesia. The Johnson-Neyman technique was used to determine the regional effect of the moderation, which indicated that when PCS scores were ≥10.6, capsaicin pain significantly moderated the association between pain and area of secondary hyperalgesia. These results suggest that catastrophizing plays an important role in the area of secondary hyperalgesia, and potentially central sensitization, warranting further testing in future research.

Dynamic Pain Phenotypes are Associated with Spinal Cord Stimulation-Induced Reduction in Pain: A Repeated Measures Observational Pilot Study.

OBJECTIVE: Spinal cord stimulation (SCS) has become a widely used treatment option for a variety of pain conditions. Substantial variability exists in the degree of benefit obtained from SCS and patient selection is a topic of expanding interest and importance. However, few studies have examined the potential benefits of dynamic quantitative sensory testing (QST) to develop objective measures of SCS outcomes or as a predictive tool to help patient selection. Psychological characteristics have been shown to play an important role in shaping individual differences in the pain experience and may aid in predicting responses to SCS. Static laboratory pain-induction measures have also been examined in their capacity for predicting SCS outcomes. METHODS: The current study evaluated clinical, psychological and laboratory pain measures at baseline, during trial SCS lead placement, as well as 1 month and 3 months following permanent SCS implantation in chronic pain patients who received SCS treatment. Several QST measures were conducted, with specific focus on examination of dynamic models (central sensitization and conditioned pain modulation [CPM]) and their association with pain outcomes 3 months post SCS implantation. RESULTS: Results suggest few changes in QST over time. However, central sensitization and CPM at baseline were significantly associated with clinical pain at 3 months following SCS implantation, controlling for psycho/behavioral factors and pain at baseline. Specifically, enhanced central sensitization and reduced CPM were associated with less self-reported pain 3 months following SCS implantation. CONCLUSIONS: These findings suggest a potentially important role for dynamic pain assessment in individuals undergoing SCS, and hint at potential mechanisms through which SCS may impart its benefit.

Nasal insufflation treatment adherence in obstructive sleep apnea.

BACKGROUND: Nasal insufflation (NI) is a novel treatment method that has been introduced for improving respiration during sleep. NI's warmed and humidified nasal airflow provides ventilatory assistance delivered as a rapidly dispersed pressure head, with minimal side wall pressures, that may affect treatment tolerability. The aim of the current study was to investigate objective and subjective adherence rates for NI therapy in mild to moderate obstructive sleep apnea (OSA). METHODS: Ten patients (three men and seven women; age, 51.3 ± 9.6 years; BMI, 32.2 ± 7.7 kg/m2 [mean ± sd]) with recently diagnosed mild to moderate OSA (10.9 ± 5.8 events/h) were investigated. A crossover design was used to compare adherence to NI and continuous positive airway pressure (CPAP) therapy using a range of objective and subjective measurements. Objective (sleep efficiency (%) and arousal indices (arousal/h)) and subjective evaluations of sleep quality were carried out each night in the laboratory. During in-home treatment, adherence for both therapies was assessed objectively (time on therapy) and subjectively (self-reported sleep diary). RESULTS: Objectively derived adherence values were comparable for CPAP and NI, with both treatment devices sharing similar usage per night (3.5 ± 2.5 vs. 3.6 ± 1.6 h/night; respectively) and the number of nights with at least 4 h of treatment (5.5 ± 4.3 vs. 6.8 ± 3.3 nights/trial, respectively). Self-reported adherence was significantly higher than objectively assessed adherence (p < 0.03). CONCLUSIONS: This study showed similar adherence to NI and CPAP over a short period of usage. A randomized clinical trial is now essential for determining the comparative effectiveness of NI therapy in relation to treatment with CPAP.

Discordance between pain and radiographic severity in knee osteoarthritis: findings from quantitative sensory testing of central sensitization.

OBJECTIVE: Radiographic measures of the pathologic changes of knee osteoarthritis (OA) have shown modest associations with clinical pain. We sought to evaluate possible differences in quantitative sensory testing (QST) results and psychosocial distress profiles between knee OA patients with discordant versus congruent clinical pain reports relative to radiographic severity measures. METHODS: A total of 113 participants (66.7% women; mean ± SD age 61.05 ± 8.93 years) with knee OA participated in the study. Radiographic evidence of joint pathology was graded according to the Kellgren/Lawrence scale. Central sensitization was indexed through quantitative sensory testing, including heat and pressure-pain thresholds, tonic suprathreshold pain (cold pressor test), and repeated phasic suprathreshold mechanical and thermal pain. Subgroups were constructed by dichotomizing clinical knee pain scores (median split) and knee OA grade scores (grades 1-2 versus 3-4), resulting in 4 groups: low pain/low knee OA grade (n = 24), high pain/high knee OA grade (n = 32), low pain/high knee OA grade (n = 27), and high pain/low knee OA grade (n = 30). RESULTS: Multivariate analyses revealed significantly heightened pain sensitivity in the high pain/low knee OA grade group, while the low pain/high knee OA grade group was less pain-sensitive. Group differences remained significant after adjusting for differences on psychosocial measures, as well as age, sex, and race. CONCLUSION: The results suggest that central sensitization in knee OA is especially apparent among patients with reports of high levels of clinical pain in the absence of moderate-to-severe radiographic evidence of pathologic changes of knee OA.

Pain, comorbidities, and clinical decision-making: conceptualization, development, and pilot testing of the Pain in Aging, Educational Assessment of Need instrument.

Introduction: Pain is highly prevalent in older adults and often contextualized by multiple clinical conditions (pain comorbidities). Pain comorbidities increase with age and this makes clinical decisions more complex. To address gaps in clinical training and geriatric pain management, we established the Pain in Aging-Educational Assessment of Need (PAEAN) project to appraise the impacts of medical and mental health conditions on clinical decision-making regarding older adults with pain. We here report development and pilot testing of the PAEAN survey instrument to assess clinician perspectives. Methods: Mixed-methods approaches were used. Scoping review methodology was applied to appraise both research literature and selected Medicare-based data. A geographically and professionally diverse interprofessional advisory panel of experts in pain research, medical education, and geriatrics was formed to advise development of the list of pain comorbidities potentially impacting healthcare professional clinical decision-making. A survey instrument was developed, and pilot tested by diverse licensed healthcare practitioners from 2 institutions. Respondents were asked to rate agreement regarding clinical decision-making impact using a 5-point Likert scale. Items were scored for percent agreement. Results: Scoping reviews indicated that pain conditions and comorbidities are prevalent in older adults but not universally recognized. We found no research literature directly guiding pain educators in designing pain education modules that mirror older adult clinical complexity. The interprofessional advisory panel identified 26 common clinical conditions for inclusion in the pilot PAEAN instrument. Conditions fell into three main categories: "major medical", i.e., cardio-vascular-pulmonary; metabolic; and neuropsychiatric/age-related. The instrument was pilot tested by surveying clinically active healthcare providers, e.g., physicians, nurse practitioners, who all responded completely. Median survey completion time was less than 3 min. Conclusion: This study, developing and pilot testing our "Pain in Aging-Educational Assessment of Need" (PAEAN) instrument, suggests that 1) many clinical conditions impact pain clinical decision-making, and 2) surveying healthcare practitioners about the impact of pain comorbidities on clinical decision-making for older adults is highly feasible. Given the challenges intrinsic to safe and effective clinical care of older adults with pain, and attendant risks, together with the paucity of existing relevant work, much more education and research are needed.

Preliminary Evidence for the Sequentially Mediated Effect of Racism-Related Stress on Pain Sensitivity Through Sleep Disturbance and Corticolimbic Opioid Receptor Function.

Sleep disturbance predicts worse pain outcomes. Because sleep disturbance inequitably impacts Black adults - with racism as the upstream cause - understanding how racism-related stress impacts pain through sleep might help minimize racialized pain inequities. This preliminary study examined sequential mediation of the effect of racism-related stress on experimental pain through sleep disturbance and corticolimbic µOR function in pain-free non-Hispanic Black (NHB) and White (NHW) adults. Participants completed questionnaires, actigraphy, positron emission tomography, and sensory testing. We reproduced findings showing greater sleep disturbance and pain sensitivity among NHB participants; greater sleep disturbance (r = .35) and lower pain tolerance (r=-.37) were significantly associated with greater racism-related stress. In a sequential mediation model, the total effect of racism-related stress on pain tolerance (ß=-.38, P = .005) weakened after adding sleep disturbance and ventromedial prefrontal cortex (vmPFC) µOR binding potential (BPND) as mediators (ß = -.18, P = .16). The indirect effect was statistically significant [point estimate = -.003, (-.007, -.0003). Findings showed a potential sequentially mediated effect of racism-related stress on pain sensitivity through sleep disturbance and vmPFC µOR BPND. As policy efforts are enacted to eliminate the upstream cause of systemic racism, these results cautiously suggest that sleep interventions within racism-based trauma informed therapy might help prevent downstream effects on pain. PERSPECTIVE: This preliminary study identified the effect of racism-related stress on pain through sleep disturbance and mu-opioid receptor binding potential in the ventromedial prefrontal cortex. Findings cautiously support the application of sleep interventions within racism-based trauma-informed therapy to prevent pain inequities as policy changes function to eliminate all levels of racism.

Pain Expectancy and Positive Affect Mediate the day-to-day Association Between Objectively Measured Sleep and Pain Severity Among Women With Temporomandibular Disorder.

The majority of individuals with temporomandibular disorders (TMD) experience sleep disturbance, which can maintain and exacerbate chronic pain. However, the factors underlying the sleep-pain link have not been fully elucidated, especially beyond the laboratory. Sleep deprivation can induce threat interpretation bias, as well as impairment in positive affective functioning. Using both actigraphy and daily diaries, we examined whether morning pain expectancy and positive affect mediate the association between previous night's sleep disturbance and next-day overall pain severity. Total sleep time (TST) was selected as the primary measure of sleep. The sample included 144 women (mean age = 36 [SD = 11.1]) with TMD who displayed at least subclinical insomnia. Sleep was assessed for 14 days using actigraphy which was validated by concurrent sleep diaries. Daily diary assessments of pain-related experiences and affective states were conducted twice per day (ie, once upon participants' waking and the other prior to going to sleep) for the same 14-day period. Multilevel structural equation modeling revealed that both morning pain expectancy (95% CI: -.0004, -.00003) and positive affect (95% CI: -.0005, -.000001) mediated the association between previous night's TST and next-day's overall pain severity, such that shorter previous night TST was associated with higher next-morning pain expectancy and lower positive affect, which in turn were associated with a greater level of next-day's overall pain severity while controlling for morning pain severity. Reducing exaggerated daily pain expectancy and up-regulating positive affect may be important intervention targets for disengaging the sleep-pain link among individuals with co-occurring TMD and sleep disturbance. PERSPECTIVE: The daily link between previous night sleep duration and next day pain severity is mediated by morning pain expectancy and positive affect among women with temporomandibular disorder and sleep disturbance. Reducing pain expectancy and increasing positive affect may serve an important role in improving self-management of chronic pain.

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

OBJECTIVES/BACKGROUND: Temporomandibular joint disorder (TMD) is a disabling facial pain syndrome with a high prevalence of insomnia that primarily affects women. Insomnia with objective short sleep duration (ISSD) is an emerging phenotype linked to cardiometabolic morbidity and increased mortality. The present report examines the association of ISSD on clinical and laboratory pain and systemic inflammation in TMD. METHODS: We collected baseline data from 128 women with TMD and insomnia as part of a clinical trial evaluating psychological interventions for sleep and pain. Participants completed self-report questionnaires, one-night polysomnography, a two-week actigraphy assessment, quantitative sensory testing (QST) to assess cold pain tolerance, pain sensitivity and central sensitization and circulating Interleukin-6 levels were measured to assess systemic inflammation. RESULTS: 24.2% (n = 31) of the sample met criteria for ISSD [polysomnography (sleep duration <6 h)]. Compared to those with insomnia and normal sleep duration, ISSD were older (40.4 vs. 34.9,p < 0.05) and a greater proportion self-identified as Black (48.4% vs 11.3%,p < 0.001). Multivariate regressions revealed that ISSD endorsed higher self-report pain severity and functional limitation of the jaw. ISSD also demonstrated increased generalized pain sensitivity, enhanced central sensitization, cold pressor tolerance and higher resting interleukin-6 levels. CONCLUSIONS: This is the first study to characterize the ISSD phenotype in a chronic pain sample and expand the scope of its negative health outcomes to chronic pain. ISSD may be an important chronic pain phenotype associated with a more severe clinical and laboratory pain profile, and future studies should focus on implications for treatment response and disease trajectory. CLINICAL TRIAL: ClinicalTrials.gov Identifier: NCT01794624.

Subjective sleep quality and ethnicity are interactively related to standard and situation-specific measures of pain catastrophizing.

OBJECTIVE: Sleep quality and ethnicity are related to a host of general health outcomes including the experience of pain, yet it remains unclear whether poor sleep quality and ethnicity might interactively affect pain catastrophizing and laboratory-evoked acute pain reports. The current study examined the cross-sectional associations of subjective sleep quality, ethnicity, and their interaction with pain catastrophizing and pain reports. DESIGN: Healthy (N = 149), ethnically diverse (58% Caucasian American, 23% Asian American, 19% African American) young adults were subjected to a cold pressor task (CPT). Prior to CPT, participants completed the Pittsburgh Sleep Quality Index and a standard version of the Pain Catastrophizing Scale (PCS). Following CPT, participants completed a situation-specific version of the PCS. RESULTS: Adjusted analyses revealed a significant sleep quality by ethnicity interaction for standard catastrophizing reports. Particularly, African Americans with poor overall sleep quality reported the greatest level of catastrophizing on the standard PCS relative to their Caucasian American and Asian American counterparts. Furthermore, African Americans with poorer sleep efficiency reported greater catastrophizing on the situation-specific PCS compared with Caucasian American and Asian Americans. Catastrophizing was significantly correlated with pain reports. CONCLUSIONS: These results suggest that African Americans with poorer sleep quality may be at greater risk for catastrophizing, a known contributor to more intense pain and increased pain-related emotional distress. Whether interventions that improve the sleep quality of ethnic minorities affect pain catastrophizing is in need of investigation.

Where to Next for Optimizing Adherence in Large-Scale Trials of Continuous Positive Airway Pressure?

Large-scale randomized trials of positive airway pressure (PAP) efficacy have been largely negative but PAP adherence was notably suboptimal across the trials. To address this limitation, evidence-based PAP adherence protocols embedded within the larger trial protocol are recommended. The complexity of such protocols depends on adequacy of resources, including funding and inclusion of behavioral scientist experts on the scientific team, and trial-specific considerations (eg, target population) and methods. Recommendations for optimizing PAP adherence in large-scale trials are set forth that address rigor and reproducibility.

Experimental sleep disruption attenuates morphine analgesia: findings from a randomized trial and implications for the opioid abuse epidemic.

Preclinical studies demonstrate that sleep disruption diminishes morphine analgesia and modulates reward processing. We sought to translate these preclinical findings to humans by examining whether sleep disruption alters morphine's analgesic and hedonic properties. We randomized 100 healthy adults to receive morphine versus placebo after two nights of undisturbed sleep (US) and two nights of forced awakening (FA) sleep disruption. Sleep conditions were counterbalanced, separated by a two-week washout. The morning after both sleep conditions, we tested cold pressor pain tolerance before and 40-min after double-blind injection of .08 mg/kg morphine or placebo. The primary outcome was the analgesia index, calculated as the change in cold pressor hand withdrawal latency (HWL) before and after drug injection. Secondary outcomes were ratings of feeling "high," drug "liking," and negative drug effects. We found a significant sleep condition by drug interaction on the analgesia index (95% CI - 0.57, - 0.001). After US, subjects receiving morphine demonstrated significantly longer HWL compared to placebo (95% CI 0.23, 0.65), but not after FA (95% CI - 0.05, 0.38). Morphine analgesia was diminished threefold under FA, relative to US. After FA, females (95% CI - 0.88, - 0.05), but not males (95% CI - 0.23, 0.72), reported decreased subjective "high" effects compared to US. After FA, females (95% CI 0.05, 0.27), but not males (95% CI - 0.10, 0.11), administered morphine reported increased negative drug effects compared to US. These data demonstrate that sleep disruption attenuates morphine analgesia in humans and suggest that sleep disturbed males may be at greatest risk for problematic opioid use.

Sleep disorders and their association with laboratory pain sensitivity in temporomandibular joint disorder.

STUDY OBJECTIVES: We characterized sleep disorder rates in temporomandibular joint disorder (TMD) and evaluated possible associations between sleep disorders and laboratory measures of pain sensitivity. DESIGN: Research diagnostic examinations were conducted, followed by two consecutive overnight polysomnographic studies with morning and evening assessments of pain threshold. SETTING: Orofacial pain clinic and inpatient sleep research facility. PARTICIPANTS: Fifty-three patients meeting research diagnostic criteria for myofascial TMD. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: We determined sleep disorder diagnostic rates and conducted algometric measures of pressure pain threshold on the masseter and forearm. Heat pain threshold was measured on the forearm; 75% met self-report criteria for sleep bruxism, but only 17% met PSG criteria for active sleep bruxism. Two or more sleep disorders were diagnosed in 43% of patients. Insomnia disorder (36%) and sleep apnea (28.4%) demonstrated the highest frequencies. Primary insomnia (PI) (26%) comprised the largest subcategory of insomnia. Even after controlling for multiple potential confounds, PI was associated with reduced mechanical and thermal pain thresholds at all sites (P < 0.05). Conversely, the respiratory disturbance index was associated with increased mechanical pain thresholds on the forearm (P < 0.05). CONCLUSIONS: High rates of PI and sleep apnea highlight the need to refer TMD patients complaining of sleep disturbance for polysomnographic evaluation. The association of PI and hyperalgesia at a nonorofacial site suggests that PI may be linked with central sensitivity and could play an etiologic role in idiopathic pain disorders. The association between sleep disordered breathing and hypoalgesia requires further study and may provide novel insight into the complex interactions between sleep and pain-regulatory processes.

Delivering Cognitive Behavioral Therapy for Insomnia in the Real World: Considerations and Controversies.

Cognitive-behavioral therapy for insomnia (CBT-I) has emerged as the first-line treatment for chronic insomnia but remains massively underused relative to the prevalence of insomnia disorder. This article focuses on 3 key issues in the delivery of CBT-I in the real world. First, where and how should CBT-I be delivered and who should deliver it? Second, who is an appropriate candidate for CBT-I? Third, how do you measure quality care with CBT-I? These issues give rise to targets for future research aimed at improving the implementation science of CBT-I in the real world.

Catastrophizing and pain-coping in young adults: associations with depressive symptoms and headache pain.

UNLABELLED: Cognitive and behavioral pain-coping strategies, particularly catastrophizing, are important determinants of the pain experience. Most studies of pain-coping are performed in samples of treatment-seeking patients with longstanding pain complaints. Individual differences in pain-coping styles may also significantly affect day-to-day pain and quality of life in nonclinical samples, though this has rarely been investigated. In particular, headache pain is common in the general population, and little is known about how pain-related coping affects pain and quality of life among headache sufferers from a nonclinical setting. In this study, 202 generally healthy subjects were divided into 2 groups, those who reported problem headaches and pain-free control subjects. Reports of pain-related catastrophizing and the use of active pain-coping strategies did not differ between the groups, but differential associations between pain-coping strategies and emotional functioning were observed. Specifically, within the headache group only, those reporting higher levels of pain catastrophizing and lower levels of active pain-coping showed the highest level of depressive symptoms. Further, higher catastrophizing was associated with greater headache pain and pain-related interference. These findings suggest that catastrophizing has little influence on emotional functioning in those without ongoing pain complaints and highlight the importance of coping in modulating the consequences of pain on day-to-day functioning, even in samples from nonclinical settings. Moreover, these findings indirectly suggest that interventions that increase adaptive coping and decrease catastrophizing may help to buffer some of the deleterious functional consequences of headache pain. PERSPECTIVE: This study adds to a growing literature that conceptualizes catastrophizing as a diathesis, or risk factor, for deleterious pain-related consequences. These data suggest that catastrophizing may require the presence of a pain condition before its detrimental effects are exerted.

Exploring the Role of Negative Cognitions in the Relationship Between Ethnicity, Sleep, and Pain in Women With Temporomandibular Joint Disorder.

Negative cognitions are central to the perpetuation of chronic pain and sleep disturbances. Patients with temporomandibular joint disorder (TMJD), a chronic pain condition characterized by pain and limitation in the jaw area, have a high comorbidity of sleep disturbances that possibly exacerbate their condition. Ethnic group differences are documented in pain, sleep, and coping, yet the mechanisms driving these differences are still unclear, especially in clinical pain populations. We recruited 156 women (79% white, 21% African American) diagnosed with TMJD as part of a randomized, controlled trial evaluating the effectiveness of interventions targeting sleep and pain catastrophizing on pain in TMJD. Analysis of baseline data demonstrated that, relative to white participants, African Americans exhibited higher levels of clinical pain, insomnia severity, and pain catastrophizing, yet there was no ethnic group difference in negative sleep-related cognitions. Mediation models revealed pain catastrophizing, but not sleep-related cognitions or insomnia severity, to be a significant single mediator of the relationship between ethnicity and clinical pain. Only the helplessness component of catastrophizing together with insomnia severity sequentially mediated the ethnicity-pain relationship. These findings identify pain catastrophizing as a potentially important link between ethnicity and clinical pain and suggest that interventions targeting pain-related helplessness could improve both sleep and pain, especially for African American patients. Perspective:Pain-related helplessness and insomnia severity contribute to ethnic differences found in clinical pain among woman with TMJD. Findings can potentially inform interventions that target insomnia and catastrophizing to assist in reducing ethnic disparities in clinical pain.

Ethnic Differences in the Effects of Naloxone on Sustained Evoked Pain: A Preliminary Study.

Ethnic differences in pain response have been well documented, with non-Hispanic Black (NHB) participants reporting enhanced clinical pain and greater laboratory-evoked pain sensitivity to a variety of quantitative sensory testing (QST) methods compared to non-Hispanic Whites (NHW). One potential mechanism that may contribute to these disparities is differential functioning of endogenous pain-regulatory systems. To evaluate endogenous opioid (EO) mechanisms in pain responses, we examined group differences in response to tonic capsaicin pain following double-blinded crossover administration of saline and the opioid antagonist, naloxone. Ten percent topical capsaicin cream and a thermode were applied to the dorsum of the non-dominant hand, maintaining a constant temperature of 40°C for 90 min. Naloxone (0.1 mg/kg) or saline placebo was administered at the 25 min mark and post-drug pain intensity ratings were obtained every 5 min thereafter. As an index of EO function, blockade effects were derived for each participant, reflecting the difference between mean post-drug pain intensity ratings under the saline versus naloxone conditions, with higher positive scores reflecting greater EO inhibition of pain. Thirty-nine healthy, young individuals (19 non-Hispanic Black [NHB], 20 non-Hispanic White [NHW]) participated. Group difference in EO function were identified, with NHB participants displaying lower EO function scores (mean=-10.8, SD=10.1) as compared to NHW participants (mean=-0.89, SD=11.5; p=0.038). NHB participants experienced significant paradoxical analgesia with naloxone. Thirty five percent of the NHW participants showed a positive blockade effect indicating EO analgesia (i.e., an increase in pain with naloxone), while only 10% of the NHB participants exhibited evidence of EO analgesia. These findings suggest differential functioning of the endogenous opioid pain regulatory system between NHB and NHW participants. Future research is warranted to examine whether these differences contribute to the disparities observed in clinical pain between groups.

Pilot study aiming to support sleep quality and duration during hospitalizations.

BACKGROUND: Sleep is a vital part to healing and recovery, hence poor sleep during hospitalizations is highly undesirable. Few studies have assessed interventions to optimize sleep among hospitalized patients. OBJECTIVE: To assess the effect of sleep-promoting interventions on sleep quality and duration among hospitalized patients. DESIGN: Quasi-experimental prospective study. SETTING: Academic medical center. PARTICIPANTS: Adult patients on the general medicine ward. INTERVENTION: Nurse-delivered sleep-promoting interventions augmented by sleep hygiene education and environmental control to minimize sleep disruption. MEASUREMENTS: Objective and subjective measurement of sleep parameters using validated sleep questionnaires, daily sleep diary, and actigraphy monitor. RESULTS: Of the 112 patients studied, the mean age was 58 years, 55% were female, the mean body mass index was 32, and 43% were in the intervention group. Linear mixed models tested mean differences in 7 sleep measures and group differences in slopes representing nightly changes in sleep outcomes over the course of hospitalization between intervention and control groups. Only total sleep time, computed from sleep diaries, demonstrated significant overall mean difference of 49.6 minutes (standard error [SE] = 21.1, P < 0.05). However, significant differences in average slopes of subjective ratings of sleep quality (0.46, SE = 0.18, P < 0.05), refreshing sleep (0.54, SE = 0.19, P < 0.05), and sleep interruptions (-1.6, SE = 0.6, P < 0.05) indicated improvements during hospitalization within intervention patients compared to controls. CONCLUSION: This study demonstrated that there is an opportunity to identify patients not sleeping well in the hospital. Sleep-promoting initiatives, both at the unit level as well as individualized offerings, may improve sleep during hospitalizations, particularly over the course of the hospitalization. Journal of Hospital Medicine 2016;11:467-472. © 2016 Society of Hospital Medicine.

Multiple Levels of Suffering: Discrimination in Health-Care Settings is Associated With Enhanced Laboratory Pain Sensitivity in Sickle Cell Disease.

OBJECTIVE: People living with sickle cell disease (SCD) experience severe episodic and chronic pain and frequently report poor interpersonal treatment within health-care settings. In this particularly relevant context, we examined the relationship between perceived discrimination and both clinical and laboratory pain. METHODS: Seventy-one individuals with SCD provided self-reports of experiences with discrimination in health-care settings and clinical pain severity, and completed a psychophysical pain testing battery in the laboratory. RESULTS: Discrimination in health-care settings was correlated with greater clinical pain severity and enhanced sensitivity to multiple laboratory-induced pain measures, as well as stress, depression, and sleep. After controlling for relevant covariates, discrimination remained a significant predictor of mechanical temporal summation (a marker of central pain facilitation), but not clinical pain severity or suprathreshold heat pain response. Furthermore, a significant interaction between experience with discrimination and clinical pain severity was associated with mechanical temporal summation; increased experience with discrimination was associated with an increased correlation between clinical pain severity and temporal summation of pain. DISCUSSION: Perceived discrimination within health-care settings was associated with pain facilitation. These findings suggest that discrimination may be related to increased central sensitization among SCD patients, and more broadly that health-care social environments may interact with pain pathophysiology.

Sleep, Pain Catastrophizing, and Central Sensitization in Knee Osteoarthritis Patients With and Without Insomnia.

OBJECTIVE: Osteoarthritis (OA), a chronic degenerative joint disorder, is characterized by joint pain. Emerging research demonstrates that a significant number of patients evidence central sensitization (CS), a hyperexcitability in nociceptive pathways, which is known to amplify and maintain clinical pain. The clinical correlates of CS in OA, however, are poorly understood. Insomnia is prevalent in older adults with OA, and recent experiments suggest associations between poor sleep and measures of CS. Catastrophizing, a potent predictor of pain outcomes, has also been associated with CS, but few studies have investigated possible interactions between catastrophizing, sleep, and CS. METHODS: We conducted a case-control study of 4 well-characterized groups of adults with insomnia and/or knee OA. A total of 208 participants completed multimodal sleep assessments (questionnaire, diary, actigraphy, and polysomnography) and extensive evaluation of pain using clinical measures and quantitative sensory testing to evaluate associations between CS, catastrophizing, and insomnia. Descriptive characterization of each measure is presented, with specific focus on sleep efficiency and CS. RESULTS: The knee OA-insomnia group demonstrated the greatest degree of CS compared to controls. In the overall sample, we found that catastrophizing moderated the relationship between sleep efficiency and CS. Specifically those with low sleep efficiency and high catastrophizing scores reported increased levels of CS. In addition, CS was significantly associated with increased clinical pain. CONCLUSION: These findings highlight the importance of assessing sleep efficiency, CS, and catastrophizing in chronic pain patients and have important clinical implications for treatment planning.