Morning Bright Light Treatment for Chronic Low Back Pain: Potential Impact on the Volatility of Pain, Mood, Function, and Sleep

Looking for a Beam of Light to Heal Chronic Pain

Chronic pain (CP) is a leading cause of disability and a potential factor that affects biological processes, family relationships, and self-esteem of patients. However, the need for treatment of CP is presently unmet. Current methods of pain management involve the use of drugs, but there are different degrees of concerning side effects. At present, the potential mechanisms underlying CP are not completely clear. As research progresses and novel therapeutic approaches are developed, the shortcomings of current pain treatment methods may be overcome. In this review, we discuss the retinal photoreceptors and brain regions associated with photoanalgesia, as well as the targets involved in photoanalgesia, shedding light on its potential underlying mechanisms. Our aim is to provide a foundation to understand the mechanisms underlying CP and develop light as a novel analgesic treatment has its biological regulation principle for CP. This approach may provide an opportunity to drive the field towards future translational, clinical studies and support pain drug development.

A Comprehensive Overview of the Neural Mechanisms of Light Therapy

Light is a powerful environmental factor influencing diverse brain functions. Clinical evidence supports the beneficial effect of light therapy on several diseases, including depression, cognitive dysfunction, chronic pain, and sleep disorders. However, the precise mechanisms underlying the effects of light therapy are still not well understood. In this review, we critically evaluate current clinical evidence showing the beneficial effects of light therapy on diseases. In addition, we introduce the research progress regarding the neural circuit mechanisms underlying the modulatory effects of light on brain functions, including mood, memory, pain perception, sleep, circadian rhythm, brain development, and metabolism.

Establishing the Reliability, Validity, and Prognostic Utility of the Momentary Pain Catastrophizing Scale for Use in Ecological Momentary Assessment Research

Despite the marked increase in ecological momentary assessment research, few reliable and valid measures of momentary experiences have been established. The goal of this preregistered study was to establish the reliability, validity, and prognostic utility of the momentary Pain Catastrophizing Scale (mPCS), a 3-item measure developed to assess situational pain catastrophizing. Participants in 2 studies of postsurgical pain outcomes completed the mPCS 3 to 5 times per day prior to surgery (N = 494, T = 20,271 total assessments). The mPCS showed good psychometric properties, including multilevel reliability and factor invariance across time. Participant-level average mPCS was strongly positively correlated with dispositional pain catastrophizing as assessed by the Pain Catastrophizing Scale (r = .55 and .69 in study 1 and study 2, respectively). To establish prognostic utility, we then examined whether the mPCS improved prediction of postsurgical pain outcomes above and beyond one-time assessment of dispositional pain catastrophizing. Indeed, greater variability in momentary pain catastrophizing prior to surgery was uniquely associated with increased pain immediately after surgery (b = .58, P = .005), after controlling for preoperative pain levels and dispositional pain catastrophizing. Greater average mPCS score prior to surgery was also uniquely associated with lesser day-to-day improvement in postsurgical pain (b = .01, P = .003), whereas dispositional pain catastrophizing was not (b = -.007, P = .099). These results show that the mPCS is a reliable and valid tool for ecological momentary assessment research and highlight its potential utility over and above retrospective measures of pain catastrophizing. PERSPECTIVE: This article presents the psychometric properties and prognostic utility of a new measure to assess momentary pain catastrophizing. This brief, 3-item measure will allow researchers and clinicians to assess fluctuations in pain catastrophizing during individuals' daily lives, as well as dynamic relationships between catastrophizing, pain, and related factors.

Sleep as a Therapeutic Target for Pain Management

PURPOSE OF REVIEW

The purpose of this review is to provide a summary of the utilization of sleep as a therapeutic target for chronic pain and to evaluate the recent literature on current and proposed pharmacologic and non-pharmacologic sleep interventions used in the management of pain disorders.

RECENT FINDINGS

Sleep is a promising therapeutic target in the treatment of pain disorders with both non-pharmacologic and pharmacologic therapies. Non-pharmacologic therapies include cognitive behavioral therapy and sensory-based therapies such as pink noise, audio-visual stimulation, and morning bright light therapy. Pharmacologic therapies include melatonin, z-drugs, gabapentinoids, and the novel orexin antagonists. However, more research is needed to clarify if these therapies can improve pain specifically by improving sleep. There is a vast array of investigational opportunities in sleep-targeted therapies for pathologic pain, and larger controlled, prospective trials are needed to fully elucidate their efficacy.

Intensity of Chronic Low Back Pain and Activity Interference: A Daily Diary Study of the Moderating Role of Cognitive Pain Coping Strategies

OBJECTIVE

Chronic low back pain (CLBP) has a significant negative impact on daily functioning, particularly for those with challenges coping adaptively with ongoing pain. However, the dynamics of pain coping in daily life remain understudied. Therefore, we examined the extent to which pain intensity interferes with daily activities, and assessed whether pain coping strategies (as assessed using daily diaries) moderated this link.

METHOD

We analyzed diary data from a sample of 84 participants with CLBP who completed daily diaries for up to 30 days rating pain intensity, pain interference with daily activities, and their use of pain coping strategies, including pain rumination (i.e., repetitive thinking about the pain and its causes), reappraisal (i.e., evaluating one's pain less negatively or more positively), and distraction (i.e., diverting attention from the pain). We hypothesized that these coping strategies would moderate the associations between pain and pain interference with daily activities, although in different directions.

RESULTS

Results suggest that pain rumination strengthens the association between pain intensity and pain interference both on the person and day level, while pain reappraisal and distraction weaken this association, at the day and person levels, respectively.

CONCLUSION

Our findings suggest that those who are more preoccupied with their pain and those who are less likely to reappraise their pain have more pain interference with daily activities. These findings build on prior work on pain coping by using daily diaries and highlight two pain coping strategies that have particular relevance for reducing the impact of CLBP in daily life.

Benefit of sunlight and melatonin on back pain and inflammation

Cite this article: Bone Joint Res  2023;12(3):199–201.

GABAergic neurons in the ventral lateral geniculate nucleus and intergeniculate leaflet modulate itch processing in mice

Itch and pain are two closely related sensations that receiving similar encodings at multiple levels. Accumulated evidences suggest that activation of the ventral lateral geniculate nucleus and intergeniculate leaflet (vLGN/IGL)-to-lateral and ventrolateral periaqueductal gray (l/vlPAG) projections mediates the antinociceptive effects of bright light therapy. Clinical study showed that bright light therapy may ameliorate cholestasis-induced pruritus. However, the underlying mechanism and whether this circuit participates in itch modulation remains unclear. In this study, chloroquine and histamine were utilized to induce acute itch models in mice. Neuronal activities in vLGN/IGL nucleus were evaluated with c-fos immunostaining as well as fiber photometry. Optogenetic manipulations were performed to activate or inhibit GABAergic neurons in the vLGN/IGL nucleus. Our results showed that the expressions of c-fos in vLGN/IGL were significantly increased upon both chloroquine- and histamine-induced acute itch stimuli. GABAergic neurons in vLGN/IGL were activated during histamine and chloroquine-induced scratching. Optogenetic activation of the vLGN/IGL GABAergic neurons exerts antipruritic effect, while inhibiting these neurons exerts pruritic effect. Our results provide evidence that GABAergic neurons in vLGN/IGL nucleus might play a crucial role in modulating itch, which may provide clue for application of bright light as an antipruritic treatment in clinic.

Comparing Types of Yoga for Chronic Low Back and Neck Pain in Military Personnel: A Feasibility Randomized Controlled Trial

Background

Chronic low back pain (cLBP) and chronic neck pain (cNP) are highly prevalent conditions and common reasons for disability among military personnel. Yoga and other mind-body interventions have been shown to safely decrease pain and disability in persons with cLBP and/or cNP but have not been adequately studied in active duty military personnel. The objective of this study was to examine the feasibility and acceptability of delivering 2 types of yoga (hatha and restorative) to a sample of active-duty military personnel with cLBP/cNP.

Methods

Military personnel with cLBP and/or cNP (n = 49; 59% men) were randomized to either hatha or restorative yoga interventions. Interventions consisted of in-person yoga 1-2x weekly for 12 weeks. Feasibility and acceptability were measured by rates of recruitment, intervention attendance, attrition, adverse events, and satisfaction ratings. Health outcomes including pain and disability were measured at baseline, 12 weeks, and 6 months. Means and effect sizes are presented.

Results

Recruitment was completed ahead of projections. Over 90% of participants agreed or strongly agreed that they enjoyed participation, liked the instructor, and would like to continue yoga. Retention rates were 86% and 80% at 12 week and 6 month assessments, respectively. Intervention attendance was adequate but lower than expected. There were small to moderate reductions in back-pain related disability, pain severity and pain interference, and improvements in quality of life, grip strength, and balance. In general, effects were larger for those who attended at least 50% of intervention classes. Participants with cNP tended to have smaller outcome improvements, but conclusions remain tentative given small sample sizes.

Conclusions

Results demonstrate feasibility for conducting a randomized controlled comparative effectiveness trial of yoga for cLBP and cNP among active duty military personnel. Acceptability was also established. Ongoing work will enhance the intervention for cNP and establish feasibility at another military facility in preparation for a fully-powered comparative effectiveness trial.ClinicalTrials #NCT03504085; registered April 20, 2018.

A visual circuit related to the periaqueductal gray area for the antinociceptive effects of bright light treatment

Light is a powerful modulator of non-visual functions. Although accumulating evidence suggests an antinociceptive effect of bright light treatment, the precise circuits that mediate the effects of light on nocifensive behaviors remain unclear. Here, we show that bright light treatment suppresses mouse nocifensive behaviors through a visual circuit related to the lateral and ventral lateral parts of the periaqueductal gray area (l/vlPAG). Specifically, a subset of retinal ganglion cells (RGCs) innervates GABAergic neurons in the ventral lateral geniculate nucleus and intergeniculate leaflet (vLGN/IGL), which in turn inhibit GABAergic neurons in the l/vlPAG. The activation of vLGN/IGL-projecting RGCs, activation of l/vlPAG-projecting vLGN/IGL neurons, or inhibition of postsynaptic l/vlPAG neurons is sufficient to suppress nocifensive behaviors. Importantly, we demonstrate that the antinociceptive effects of bright light treatment are dependent on the activation of the retina-vLGN/IGL-l/vlPAG pathway. Together, our results delineate an l/vlPAG-related visual circuit underlying the antinociceptive effects of bright light treatment.

Healthy Dwelling: Design of Biophilic Interior Environments Fostering Self-Care Practices for People Living with Migraines, Chronic Pain, and Depression

The benefits of biophilic interior design have been recognized by healthcare facilities, but residential environments receive relatively less attention with respect to improving the health of people living with chronic diseases. Recent “stay-at-home” restrictions due to the COVID-19 pandemic further emphasized the importance of creating interior spaces that directly and indirectly support physical and mental health. In this viewpoint article, we discuss opportunities for combining biophilic interventions with interior design, fostering disease-specific self-care. We provide examples of designing residential spaces integrating biophilic interventions, light therapy, relaxation opportunities, mindfulness meditation, listening to music, physical activities, aromatherapy, and quality sleep. These modalities can provide the clinical benefits of reducing migraine headaches and chronic pain, as well as improving depressive symptoms. The disease-specific interior environment can be incorporated into residential homes, workplaces, assisted-living residences, hospitals and hospital at home programs. This work aims to promote a cross-disciplinary dialogue towards combining biophilic design and advances in lifestyle medicine to create therapeutic interior environments and to improve healthcare outcomes.

The role of affect in chronic pain: A systematic review of within-person symptom dynamics

OBJECTIVE

Chronic pain is conceptualized as a biopsychosocial phenomenon that involves both physical and emotional processes. The vast majority of research regarding these facets of chronic pain characterizes differences between individuals. In this review, we describe problems with assuming that differences between persons accurately characterize within-person processes. We also provide a systematic review of studies that have examined within-person relationships between pain and affect among individuals with chronic pain.

METHOD

Articles published by December 2020 that pertained to within-person assessment of pain and emotion, affect, or mood were identified. Data regarding study design, adherence, and concurrent and prospective relationships among pain and affect variables were extracted and summarized.

RESULTS

Of 611 abstracts, 55 studies met inclusion criteria. Results suggest that individuals with chronic pain tend to experience increased negative affect and decreased positive affect when experiencing more severe pain (r_pooled = .18 and - .19, respectively). However, the size of these effects appeared smaller than between-person associations, and there was evidence of significant variability between individuals. Examination of predictive relationships between pain and affect largely suggested the tendency of symptoms to predict themselves, rather than pain predicting affect or vice versa.

CONCLUSIONS

Consistent with group-level relationships, experiencing more severe pain relative to an individual's average seems to be associated with more negative affect and less positive affect. However, individuals vary in the size and even direction of these effects. More research is necessary to understand the implications of such variability for the assessment and treatment of chronic pain.

Mechanisms and Pathways of Pain Photobiomodulation: A Narrative Review

A growing body of evidence supports the modulation of pain by light exposure. As such, phototherapy is being increasingly utilized for the management of a variety of pain conditions. The modes of delivery, and hence applications of phototherapy, vary by wavelength, intensity, and route of exposure. As such, differing mechanisms of action exist depending upon those parameters. Cutaneous application of red light (660 nm) has been shown to reduce pain in neuropathies and complex regional pain syndrome-I, whereas visual application of the same wavelength of red light has been reported to exacerbate migraine headache in patients and lead to the development of functional pain in animal models. Interestingly visual exposure to green light can result in reduction in pain in variety of pain conditions such as migraine and fibromyalgia. Cutaneous application typically requires exposure on the order of minutes, whereas visual application requires exposure on the order of hours. Both routes of exposure elicit changes centrally in the brainstem and spinal cord, and peripherally in the dorsal root ganglia and nociceptors. The mechanisms of photobiomodulation of pain presented in this review provide a foundation in furtherance of exploration of the utility of phototherapy as a tool in the management of pain. PERSPECTIVE: This review synopsizes the pathways and mechanisms through which light modulates pain and the therapeutic utility of different colors and exposure modalities of light on pain. Recent advances in photobiomodulation provide a foundation for understanding this novel treatment for pain on which future translational and clinical studies can build upon.

The influence of sleep disturbances and sleep disorders on pain outcomes among veterans: A systematic scoping review

Chronic nonmalignant pain, sleep disturbances and sleep disorders are highly prevalent conditions among U.S. military veterans. Evidence summaries highlight the influence of sleep on pain outcomes in the general adult population but not for the military veteran population. This is a significant gap as U.S. military veterans are an exceedingly high-risk population for both chronic pain and sleep disturbances and/or disorders. We aimed to review the influence of sleep disturbances and sleep disorders on pain outcomes among veterans with chronic nonmalignant pain. A systematic scoping review was conducted using PubMed/Medline, EMBASE, Scopus, CINAHL, and PsycINFO. Twenty-six out of 1450 studies from initial search were included in this review resulting in a combined sample size of N = 923,434 participants. Sleep disturbances and sleep disorders were associated with worse pain outcomes among veterans with chronic pain. Treatment-induced sleep improvements ameliorated pain outcomes in veterans with sleep disorders and sleep disturbances. Research is indicated to address an overlooked pain treatment opportunity - that of sleep disturbance and sleep disorder management.