Pain and severe sleep disturbance in the general population: Primary data and meta-analysis from 240,820 people across 45 low- and middle-income countries

A Narrative Review of the Reciprocal Relationship Between Sleep Deprivation and Chronic Pain: The Role of Oxidative Stress

Sleep is crucial for human health, insufficient sleep or poor sleep quality may negatively affect sleep function and lead to a state of sleep deprivation. Sleep deprivation can result in various health problems, including chronic pain. The intricate relationship between sleep and pain is complex and intertwined, with daytime pain affecting sleep quality and poor sleep increasing pain intensity. The article first describes the influence of sleep on the onset and development of pain, and then explores the impact of daytime pain intensity on nighttime sleep quality and subsequent pain thresholds. However, the primary emphasis is placed on the pivotal role of oxidative stress in this bidirectional relationship. Although the exact mechanisms underlying sleep and chronic pain are unclear, this review focuses on the role of oxidative stress. Numerous studies on sleep deprivation have demonstrated that it can lead to varying degrees of increased pain sensitivity, while chronic pain leads to sleep deprivation and further exacerbates pain. Further research on the role of oxidative stress in the mechanism of sleep deprivation-induced pain sensitization seems reasonable. This article comprehensively reviews the current research on the interrelationship between sleep deprivation, pain and the crucial role of oxidative stress.

Mediterranean diet adherence and sleep pattern: a systematic review of observational studies

BACKGROUND AND AIMS

Despite a huge body of evidence on the linkage between dietary intakes and pattern of sleeping, the findings are controversial. The current study aimed to summarize earlier findings on the association between adherence to Mediterranean diet (MD) and pattern of sleeping.

METHODS

This study performed based on PRISMA guideline. Systematically search was applied in PubMed, Scopus and Google Scholar to find out relevant publications appeared up to February 2023. No restrictions on language and time of publication were applied. Duplicate citations were removed. We included observational studies which assessed MD as the main exposure and kind of sleep disorders as the main outcome.

RESULTS

A total of 20 observational studies included. Out of these studies, two were cohort studies and 18 had a cross-sectional design. A total of 21,714 participants included. Usual dietary intakes were assessed using a validated Food Frequency Questionnaire, and a diet history questionnaire. Some studies did not report methods of measuring habitual dietary intakes. Adherence to MD was evaluated by KIDMED questionnaire, PREMED, alternate Mediterranean (aMed) questionnaire, MEDAS questionnaire, MedDietScore, MEDI-LITE score, modified Mediterranean Diet Score (mMDS), Mediterranean food pattern (MFP) and modified Mediterranean diet score (mMED). Pattern of sleeping was examined as sleep quality, sleep duration, sleep latency, sleep efficacy, sleepiness, sleep disturbance, taking a nap and some other sleep disorders.

CONCLUSION

In conclusion, findings of published studies highlighted the importance of consumption of MD for better sleep quality.

Improvement of sleep and pain with lemborexant administration in patients with chronic pain: a retrospective observational study

OBJECTIVE

Patients with chronic pain often have sleep disturbances, and many patients receive sleep medications in addition to analgesics. Although there have been scattered reports of negative pain-sleep interactions, only a few reports have investigated the efficacy of sleep medication interventions in patients with chronic pain for improving sleep disturbances and reducing pain. We retrospectively examined whether lemborexant, an orexin receptor antagonist, is effective in improving sleep disturbances and reducing pain in patients with chronic pain. This study was approved by the Ethics Committee of our hospital.

METHODS

The subjects were 26 patients with chronic pain undergoing treatment at our pain clinic between July 2021 and March 2022, who had been diagnosed with insomnia, with an Athens Insomnia Scale (AIS) score of ≥6 and had been started on lemborexant. The AIS score and pain score (Numeric Rating Scale [NRS]) before and after 2 and 4 weeks of starting lemborexant were investigated.

RESULTS

Patients who were already taking other sleep medications, such as benzodiazepines were switched to 5 mg of lemborexant after all the other sleep medications were discontinued. Those who had not yet used sleeping pills were started on 5 mg of lemborexant. During the study course, the dose of lemborexant was adjusted at the discretion of the attending physician, based on improvement of insomnia symptoms and secondary symptoms, such as daytime sleepiness and lightheadedness. The study finally included 21 patients, excluding 5 who could not continue taking lemborexant due to side effects, such as lightheadedness. The AIS scores significantly improved, decreasing from baseline (mean ± standard deviation: 12.5 ± 4.9) to 2 weeks (7.8 ± 3.1) and 4 weeks (5.3 ± 2.9) after the start of lemborexant. No significant difference was observed in the degree of improvement in sleep disturbance between patients with or without previous sleep medications, and there was also no statistically significant improvement in the NRS score before (6.1 ± 2.7) and after 2 weeks (5.5 ± 2.3) and 4 weeks (5.9 ± 2.2) from treatment initiation.

Participatory action research intervention for improving sleep in inpatients with cancer

AIM

To design and implement a plan to improve oncohaematological patients' sleep.

BACKGROUND

The hospital environment can compromise inpatients' sleep, negatively impacting on health outcomes and patient satisfaction.

DESIGN AND METHOD

The improvement plan was designed in collaboration with 18 professionals, 3 patients and 3 accompanying relatives. The study designed followed the SQUIRE 2.0 guidelines. Outcome variables were self-reported patient satisfaction regarding sleep, measured using a 30-item, ad hoc questionnaire and a 10-point visual analogue scale, completed by 318 oncohaematological inpatients (pre-intervention n = 120, post-intervention, n = 198) in a comprehensive cancer centre in Spain from 2017 to 2019.

RESULTS

Overall, 61.5% (n = 190) of the inpatients reported sleep alterations, and 92.6% reported interruptions in their nightly sleep. Half slept less than 6 h/night, but 58.0% said they felt rested upon waking, despite the interruptions. These outcomes were similar before and after the intervention. The improvement plan identified four domains for work (professionals, care procedures, instruments/environment and patients/relatives), 10 areas for improvement and 35 actions for implementation. However, overall sleep worsened significantly, from 6.73 to 6.06 on the 10-point scale. The intervention significantly improved variables related to professionals' behaviour, including noise during the shift change, conversations at the control desk and the use of corridor lights. Sleep disturbances were mainly caused by pain/discomfort and infuser alarms, and collectively they decreased significantly after the intervention (p = .008). However, overall sleep worsened significantly, from 6.73 to 6.06 on the 10-point scale.

CONCLUSIONS

Pain, clinical devices and noise made by professionals are the main causes of sleep disturbances. Involving professionals in decision-making to improve patients' sleep have a positive impact on noise levels.

RELEVANCE TO CLINICAL PRACTICE

This study proposes new strategies for improving sleep by increasing staff awareness and changing attitudes towards patients' sleep. Nurses should be involved in addressing sleep disturbances during hospitalization.

Sleep quality and sleep-related issues in industrial workers: a global meta-analysis

Objectives. Sleep-related issues are important health issues. This study aimed to investigate the global prevalence of sleep-related issues in industrial workers. Methods. A syntax of keywords was used to search the PubMed, Web of Science and Scopus databases. The search time was limited to articles published until September 2020, and the search range was in English. Events and samples were extracted for each study to calculate the prevalence. For all subgroups, events and samples were extracted to calculate the results of the subgroups. The random-effects method was used in the analysis. Heterogeneity was examined at the levels of all analyses. Results. Forty-eight articles were included in the analysis as eligible studies. Sleep-related issues have 30% prevalence in the 95% confidence interval (CI) [25, 35%]. The prevalence of sleep-related issues in men was 38%, 95% CI [31, 45%] and in women was 32%, 95% CI [14, 50%]. The prevalence of poor sleep quality, insomnia, sleep duration <7 h, snoring and sleepiness was 36, 22, 37, 29 and 10%, respectively. Conclusions. Sleep-related issues have a high prevalence in industrial workers, and the cause of these differences needs to be addressed and increasing insights provided to prevent and treat sleep disorders.

Chronic pain recruits hypothalamic dynorphin/kappa opioid receptor signalling to promote wakefulness and vigilance

Increased vigilance in settings of potential threats or in states of vulnerability related to pain is important for survival. Pain disrupts sleep and conversely, sleep disruption enhances pain, but the underlying mechanisms remain unknown. Chronic pain engages brain stress circuits and increases secretion of dynorphin, an endogenous ligand of the kappa opioid receptor (KOR). We therefore hypothesized that hypothalamic dynorphin/KOR signalling may be a previously unknown mechanism that is recruited in pathological conditions requiring increased vigilance. We investigated the role of KOR in wakefulness, non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep in freely moving naïve mice and in mice with neuropathic pain induced by partial sciatic nerve ligation using EEG/EMG recordings. Systemic continuous administration of U69,593, a KOR agonist, over 5 days through an osmotic minipump decreased the amount of NREM and REM sleep and increased sleep fragmentation in naïve mice throughout the light-dark sleep cycle. We used KORcre mice to selectively express a Gi-coupled designer receptor activated by designer drugs (Gi-DREADD) in KORcre neurons of the hypothalamic paraventricular nucleus, a key node of the hypothalamic-pituitary-adrenal stress response. Sustained activation of Gi-DREADD with clozapine-N-oxide delivered in drinking water over 4 days, disrupted sleep in these mice in a similar way as systemic U69,593. Mice with chronic neuropathic pain also showed disrupted NREM and total sleep that was normalized by systemic administration of two structurally different KOR antagonists, norbinaltorphimine and NMRA-140, currently in phase II clinical development, or by CRISPR/Cas9 editing of paraventricular nucleus KOR, consistent with endogenous KOR activation disrupting sleep in chronic pain. Unexpectedly, REM sleep was diminished by either systemic KOR antagonist or by CRISPR/Cas9 editing of paraventricular nucleus KOR in sham-operated mice. Our findings reveal previously unknown physiological and pathophysiological roles of dynorphin/KOR in eliciting arousal. Physiologically, dynorphin/KOR signalling affects transitions between sleep stages that promote REM sleep. Furthermore, while KOR antagonists do not promote somnolence in the absence of pain, they normalized disrupted sleep in chronic pain, revealing a pathophysiological role of KOR signalling that is selectively recruited to promote vigilance, increasing chances of survival. Notably, while this mechanism is likely beneficial in the short-term, disruption of the homeostatic need for sleep over longer periods may become maladaptive resulting in sustained pain chronicity. A novel approach for treatment of chronic pain may thus result from normalization of chronic pain-related sleep disruption by KOR antagonism.

The Effect of Sleep Quality on Pain in Chilean Individuals with Musculoskeletal Disorders

Poor sleep quality (SQ) negatively affects pain associated with musculoskeletal disorders (MSD). As the level of economic development of a country determines its sanitary conditions, these can influence the sleep–pain relationship; therefore, it is relevant to generate evidence in the population with MSD in developing countries. This cross-sectional study sought to determine the effect of poor SQ on pain in Chilean individuals with MSD, controlling for sex and duration of pain (in months). Method: A total of 228 individuals were included. SQ was measured with the Pittsburg Sleep Quality Index (PSQI), pain (intensity, interference and distress relative to pain) was measured with visual analog scales. Structural equation modeling (SEM) was performed to analyze the effect of SQ on pain. Results: A high frequency of poor SQ was present in the studied group, and was more prevalent in women. The SEM model evidenced that poor SQ predicts greater pain. Sex influences sleep quality and pain, but not pain duration. Conclusions: These findings indicate that poor SQ predicts higher pain in MSD and that women exhibit worse SQ and more significant pain than men. Our findings support that SQ should be considered in the comprehensive approach to pain in individuals with MSD.

Longitudinal association of apolipoprotein E and sleep with incident dementia

INTRODUCTION

Few longitudinal studies have explored the association between apolipoprotein E gene (APOE) status, sleep disturbances, and incident dementia among middle-aged participants.

METHODS

Cox regression analyses explored the association of sleep duration, insomnia, and daytime napping with incident all-cause dementia and their interaction with APOE genetic risk among 397,777 middle-aged adults.

RESULTS

During a median of 10.8 years follow-up, sleeping more or fewer than 7 hours was associated with a higher dementia risk (hazard ratio [HR] for 5 vs 7 hours: 1.35, 95% confidence interval [CI] 1.11-1.64; HR for 9 vs 7 hours: 1.59; 95% CI 1.37-1.85) as was daytime napping (HR for often/all of the time vs never/rarely: 1.67; 95% CI 1.37-2.03). Stratified analyses revealed that the effects of sleep disturbances were similar across all APOE genetic risk groups.

DISCUSSION

Short and long sleep duration and daytime napping in middle-aged individuals are associated with the development of dementia in later life. Sleep duration and quality are important for everyone regardless of their genetic risk by APOE genotype.

Evaluation of Subjective Sleep Disturbances in Cancer Patients: A Cross-Sectional Study in a Radiotherapy Department

Background: The factors associated with sleep disturbances in cancer patients remains unclear. This study aimed to explore the prevalence of sleep disorders and predictors associated with sleep disturbance in cancer patients from a radiotherapy department. Methods: Patients with cancers were recruited before the start of radiotherapy from our institution between January 2019 and February 2020. Pittsburgh Sleep Quality Index (PSQI) scale was used to assess sleep quality. Descriptive statistics, Chi-square test, and multivariate logistic regression analysis were used to conduct statistical analysis. Results: A total of 330 eligible patients were included. Of them, 38.3% (n = 127) had the globe PSQI score >7, indicating that they suffered from sleep disorders. Patients with lung cancer (45.2%) were more likely to suffer from sleep disturbance, followed by cervical cancer (43.8%), nasopharyngeal carcinoma (41.7%), esophageal cancer (41.5%), breast cancer (37.7%), and colorectal cancer (30%). With regard to the PSQI components, the mean sleep duration was 8 h, 20.3% (n = 67) of them reported poor subjective sleep quality, 6.1% (n = 20) needed medication to improve sleep, and 53.6% (n = 177) suffered daytime dysfunction. Multivariate logistic regression models showed body mass index (BMI) ≥ 20 kg/m² [odds ratio (OR) 0.599, 95% confidence interval (CI) 0.329-0.948, P = 0.031] and the receipt of surgery (OR 0.507, 95% CI 0.258-0.996, P = 0.048) were the significant favorable predictors for sleep disturbance, while age, gender, marital status, education level, comorbidity, metastasis status, diagnostic status, and cancer type were not significantly associated with sleep disturbance. Conclusions: Approximately 40% of the cancer patients suffer from sleep disturbance before the start of radiotherapy. Patients with BMI ≥ 20 kg/m² and receiving surgery are less likely to develop sleep disturbance in comparison with others.

Social Network and Risk of Poor Sleep Outcomes in Older Adults: Results from a Spanish Prospective Cohort Study

BACKGROUND

Not having social support has been associated with poor sleep, but most prospective studies were based on social support in the workplace, did not account for baseline sleep characteristics or did not assess sleep duration. Moreover, no previous research has evaluated the relationship between social network and sleep outcomes in an older Spanish population.

METHODS

1444 individuals aged ≥60 years were followed between 2012 and 2015. At baseline (2012), a poor social network index (SNI) was computed by summing the following dichotomous indicators: not being married; living alone; not having daily contact with family, friends or neighbors; being alone ≥8h/day; lacking someone to go for a walk with; not having emotional support; lacking instrumental support. Higher values in SNI indicate less social support. In 2012 and 2015, information was collected on sleep duration (hours/day) and on symptoms of sleep disturbance: bad overall sleep; difficulty falling asleep, awakening during nighttime, early awakening with difficulty getting back to sleep, use of sleeping pills, feeling restless in the morning, being asleep at daytime, and having an Epworth Sleepiness Scale>10. Poor sleep duration was defined as short (<6 h) or long (>9 h) nighttime sleep, and poor sleep quality as having ≥4 indicators of sleep disturbance. Linear or logistic regression models were used to assess the relationship of SNI with changes in sleep duration and in number of sleep disturbance indicators, or with the risk of developing poor nighttime sleep or poor sleep quality.

RESULTS

Compared to individuals in the lowest (best) quartile of the SNI in 2012, those in the second, third and fourth quartiles, respectively, displayed a mean (95%confidence interval [95% CI]) change of 2.32 (-7.58-12.22), -2.70 (-13.19-7.79) and -13.04 (-23.41- -2.67) minutes in sleep duration from 2012 to 2015; p for trend=0.02. A 1-point increase in the SNI at baseline was associated with an increased risk of short nighttime sleep (Odds Ratio [OR] and 95% CI: 1.22 (1.05-1.42)), poor sleep quality (OR: 1.13; 95% CI: 1.00-1.30), and of the indicator of sleep disturbance "early awakening with difficulty getting back to sleep" (OR: 1.20; 95% CI: 1.07-1.35).

CONCLUSION

A poorer social network is associated with a higher risk of short sleep and poor sleep quality in older adults.

When to consider "mixed pain"? The right questions can make a difference!

The term "mixed pain" is increasingly applied for specific clinical scenarios, such as low back pain, cancer pain and postsurgical pain, in which there "is a complex overlap of the different known pain types (nociceptive, neuropathic, nociplastic) in any combination, acting simultaneously and/or concurrently to cause pain in the same body area." Whether mixed pain is the manifestation of neuropathic and nociceptive mechanisms operating simultaneously or concurrently, or the result of an entirely independent pathophysiological mechanism - distinct from nociceptive, nociplastic and neuropathic pain - is currently unknown. At present, the diagnosis of mixed pain is made based on clinical judgement following detailed history-taking and thorough physical examination, rather than by formal confirmation following explicit screening or diagnostic criteria; this lack of formalized screening or diagnostic tools for mixed pain is problematic for physicians in primary care, who encounter patients with probable mixed pain states in their daily practice. This article outlines a methodical approach to clinical evaluation of patients presenting with acute, subacute or chronic pain, and to possibly identifying those who have mixed pain. The authors propose the use of nine simple key questions, which will provide the practicing clinician a framework for identifying the predominant pain mechanisms operating within the patient. A methodical, fairly rapid, and comprehensive assessment of a patient in chronic pain - particularly one suffering from pain with both nociceptive and neuropathic components - allows validation of their experience of chronic pain as a specific disease and, importantly, allows the institution of targeted treatment.

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.

Sleep Quality in Patients with Rheumatoid Arthritis and Associations with Pain, Disability, Disease Duration, and Activity

We aimed to assess the subjective sleep quality in patients with rheumatoid arthritis (RA) and its correlation with disease activity, pain, inflammatory parameters, and functional disability. In a cross-sectional study, patients with confirmed RA diagnosis responded to a questionnaire (consisting of socio-demographic data, the Health Assessment Questionnaire Disability Index, and the Medical Outcome Study Sleep Scale). Disease activity was assessed with the Clinical Disease Activity Index, and pain levels using the visual analogue scale. In addition, inflammatory markers (C-reactive protein, interleukin-6, and tumor necrosis factor alpha) were analyzed. Ninety-five patients were analyzed, predominantly female, with an average age of 50.59 (9.61) years. Fifty-seven percent reported non-optimal sleep duration, where functional disability (92.7% vs. 69.8%; p = 0.006) and higher median pain levels (3.75 (2.3–6.0) vs. 2.5 (2.0–3.5); p = 0.003) were also more prevalent. No differences in sociodemographic variables, disease duration or activity, inflammatory parameters, or use of biological and corticosteroid therapy were observed. The multivariate regression analysis showed that more intense pain was associated with a lower likelihood of optimal sleep (odds ratio (OR) = 0.68, 95% confidence interval (CI) 0.47–0.98, p = 0.038). Patients with RA report a high prevalence of non-optimal sleep, which is linked to pain level. Clinicians need to be aware of this issue and the potential effects on health and functional status.