Abstract
Chronic pain affects the quality of life for millions of people worldwide. There is a bidirectional link between pain and sleep: poor sleep quality exacerbates pain, and pain disrupts sleep. Addressing this cycle is crucial for effective pain management and improving patients’ overall health outcomes.
Chronic pain affects the quality of life for millions of people worldwide. There is a bidirectional link between pain and sleep: poor sleep quality exacerbates pain, and pain disrupts sleep. Addressing this cycle is crucial for effective pain management and improving patients’ overall health outcomes.
Main text
Introduction
Chronic pain (CP) is a complex condition affecting millions globally, severely impairing daily functioning and reducing overall well-being.1 The condition is characterized by persistent pain that lasts three to six months beyond typical tissue healing. An estimated 13%–25% of adults suffer from CP.1 Managing CP requires a range of physical, psychological, and social factors.1 Although research highlights a well-known link between CP and sleep disturbances, sleep quality is often disregarded in clinical settings.2
Sleep is essential for maintaining homeostasis, physical functioning, and mental health.2 CP and sleep disorders are intricately connected, influencing each other in a bidirectional relationship that significantly impacts quality of life.2 Sleep disturbances (i.e., insomnia, poor sleep quality, and sleep insufficiency) are associated with decreased physical and mental well-being.2 Approximately 50%–88% of individuals with CP report sleep difficulties, making it a primary complaint.3 This high prevalence underscores the importance of simultaneously addressing pain and sleep issues in treatment strategies, requiring a multidisciplinary approach for effective management.2,3
The bidirectional relationship between sleep and pain has important clinical implications for pain management and CP prevention. This commentary briefly summarizes the relationship between CP and sleep, provides an overview of sleep disorder assessment, and focuses on current recommendations for CP management.
Characteristics of CP and sleep
Unlike acute pain, which is a protective response to injury, CP frequently lacks a physical cause.1 It persists even after the original injury or condition has healed and tends to resist conventional treatments.1 Manifestations of CP include neuropathic pain, nociceptive pain, and centralized pain syndromes, commonly associated with conditions like fibromyalgia, arthritis, and chronic back pain.1,2 A complex interplay of physical and psychological factors can perpetuate and intensify CP.1 Comorbidities such as sleep disturbances, anxiety, depression, and impaired physical function are common.1,2,4
The vicious cycle of pain and sleep disturbance
Sleep is crucial for physical recovery, emotional well-being, and cognitive function, yet individuals with CP often struggle to achieve restful sleep.2,5 Like CP, sleep disorders are a significant public health problem affecting overall health.5 More than a quarter of the world’s population suffers from sleep disorders, with insomnia being the most common diagnosis.5 A recent meta-analysis found a high prevalence of sleep disorders in people with CP, including insomnia (72%), obstructive sleep apnea (32%), and restless legs syndrome (32%).6
CP contributes significantly to poor sleep quality, with pain-related arousals leading to fragmented and non-restorative sleep.6 Conversely, at least 40% of individuals with insomnia also suffer from CP. This bidirectional link creates a vicious cycle: CP disrupts sleep quality, which in turn increases pain sensitivity, intensifies pain perception, and reduces the body’s ability to cope with pain, ultimately affecting overall health outcomes.5,6,7
The role of emotional and cognitive functioning
Poor sleep quality can lead to cognitive impairments such as reduced concentration and memory decline, as well as depressive symptoms, anxiety, and mood disturbances—all of which negatively affect pain management.4 A recent systematic review identified several mediators in the sleep-pain relationship, including mood, depression, anxiety, stress, fatigue, and physical activity.4 Additionally, research has shown that sleep disturbances can mediate the relationship between depression and CP.8 These cognitive and emotional challenges can further exacerbate the experience of pain, creating additional barriers to effective pain management.4,8
The effect of sleep disturbances on pain perception
Sleep disturbances decrease the pain threshold, increase sensitivity to pain stimuli, and significantly impact pain perception.5,7 The heightened sensitivity is partly a result of the disruption to the body’s natural pain-modulating systems.7 During sleep, the body produces endorphins and other neurochemicals that help manage pain.7 Insufficient or disrupted sleep impairs these processes, leading to increased pain sensitivity.5,7
Underlying mechanisms of pain and sleep
Various neurobiological and physiological mechanisms, including the dysregulation of neurotransmitters, the hypothalamic-pituitary-adrenal (HPA) axis, and inflammatory pathways, mediate the sleep-pain relationship.5
Neurotransmitters such as dopamine, serotonin, and norepinephrine are essential for regulating pain and sleep.5,7 Dysregulation of these neurotransmitters can contribute to the persistence of both conditions.5,7 For instance, serotonin regulates mood and pain perception, and its dysregulation commonly occurs in individuals with CP and sleep disturbances.5,7,8
The HPA axis, a central component of the stress response system, also plays a critical role in regulating pain and sleep.7 HPA axis dysfunction can increase cortisol levels, contributing to CP and sleep disorders. Research suggests that CP activates the HPA axis, increases stress, and exacerbates sleep disturbances. This creates a feedback loop where stress-induced sleep disturbances worsen CP, and CP, in turn, leads to higher levels of stress.7
Sleep disturbances also affect the inflammatory processes in the body.7 Conditions associated with CP, such as arthritis and fibromyalgia, often increase inflammation, and poor sleep quality can exacerbate it. Thus, inflammation is a critical mediator in the development and persistence of CP.7 Sleep disturbances can increase levels of proinflammatory cytokines, further worsening pain and perpetuating a cycle of inflammation and disrupted sleep.7 Recent research indicates that proinflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 play crucial roles in pain pathways affecting sleep architecture and leading to sleep disturbances such as insomnia.5
Assessment of sleep disorders
Objective methods
Objective methods such as polysomnography (PSG) and actigraphy are commonly used in sleep medicine to assess sleep quality.9 Sleep indicators for CP patients include sleep onset latency (SOL), wakefulness after sleep onset (WASO), sleep efficiency (SE), and total sleep time (TST). For objective monitoring, PSG and actigraphy are highly reliable.9 PSG, the gold standard, involves numerous sensors and must be conducted in a laboratory by trained technicians. The disadvantages are that it may disrupt natural sleep patterns and is costly and time consuming. Alternatively, researchers widely use actigraphy for home sleep assessment. It is non-invasive, relatively inexpensive, and tracks sleep-wake patterns over days to months. Actigraphy is valuable for sleep rhythm disturbances, emotional disorders, and abnormal body movements.9 It is less accurate than PSG is in detecting wakefulness during sleep and does not provide detailed sleep architecture information.9 Therefore, using at least one electroencephalogram (EEG) channel for sleep measurement remains the preferred method for assessing sleep quality.9
Subjective methods
Subjective methods such as self-report questionnaires, including the Insomnia Severity Index (ISI), Mini Sleep Questionnaire (MSQ), Epworth Sleep Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and sleep diaries, are commonly used due to their time and cost efficiency.3,9 These tools evaluate various aspects of sleep, such as subjective sleep quality, latency, duration, efficiency, disturbances, use of sleep medications, and daytime dysfunction.9 The PSQI and the sleep diary are the most widely accepted methods and are regarded as the gold standard for assessing subjective sleep quality.3,9
The utility of each measure varies depending on the nature and severity of the sleep disorder and the specific sleep characteristics being assessed.9 When selecting an appropriate sleep assessment, it is essential to consider the dynamics of the clinical setting, such as time limitations, the impact on patients, and the resources available to staff.3,9
Interventions and current recommendations
The complex interaction between CP and sleep disorders necessitates a multidisciplinary treatment approach.2,3 Integrating sleep interventions with CP management strategies can alleviate pain, improve sleep quality, and increase overall well-being.2,3,4,8 Addressing factors like anxiety or depression that contribute to poor sleep is also critical in breaking the sleep-pain cycle.7 Current treatments for sleep disorders in CP patients include non-pharmacological and pharmacological interventions.7,9
Non-pharmacological interventions
Cognitive behavioral therapy
Non-pharmacological methods such as evidence-based cognitive behavioral therapy (CBT) for pain (CBT-P) and CBT for insomnia (CBT-I) are effective, cost efficient, and enhance clinical outcomes.7,9 CBT is the primary psychological treatment for CP and is also recommended for sleep disorders. Additionally, CBT is the first-line treatment for insomnia according to current guidelines.10 Despite their benefits, clinicians underuse these psychological strategies due to insufficient training or limited access.11 A recent systematic review and meta-analysis revealed that CBT-I is the most effective treatment for those with comorbid insomnia and CP.12 It includes psychoeducation, stimulus control, sleep restriction, sleep hygiene, relaxation training, and cognitive therapy, targeting negative thought and behavior patterns to enhance sleep quality and alleviate pain perception.11,12
CBT-P has been highly effective in reducing patient distress across various types of CP.7,12 However, despite the expectation that improved pain management would enhance sleep, studies have shown mixed results.12 Few studies evaluating CBT-P in CP populations have focused on sleep, and these studies have found only minimal improvement in sleep quality.12
A recent randomized control trial (RCT) suggested that CBT-I is more effective than CBT-P is in improving sleep outcomes in patients with chronic insomnia and fibromyalgia (Table 1; https://clinicaltrials.gov, identifier: NCT02001077). Given these findings, CP patients with insomnia may benefit more from interventions specifically targeting sleep disturbances rather than relying solely on CBT-P. Thus, while CBT-P is valuable for managing pain, addressing sleep issues directly may be necessary for comprehensive patient care.11
Table 1.
Selected randomized clinical trials testing non-pharmacological interventions for CP and sleep disorders
| Trial number | Pathology | Intervention | Details | Comments |
|---|---|---|---|---|
| PACTR20180 7573146508 |
chronic neck pain | Pilates and neck exercises | single blind, 45 patients, 8 weeks | improvement in sleep; disturbance and chronic musculoskeletal neck pain |
| NCT02001077 | chronic insomnia; fibromyalgia |
cognitive behavioral therapy | 78 participants (39 control), 8 sessions each 50 min | improvement in sleep quality after sleep onset and sleep efficiency for 6 months; CBT-I was superior to CBT-P |
| JIRB N201604055 | fibromyalgia | neurofeedback training | 80 participants (20 control), 8 weeks each 30 min | improvements in pain severity, pain interference, fibromyalgia symptom severity, sleep latency |
| NCT01343927 | non-specific lower back pain | yoga classes and aerobic exercises | 320 participants (64 control), 12 weeks/40 weeks maintenance | improved sleep quality |
| NCT03441997 | fibromyalgia | Qigong exercise, breathing, and meditation | double-blind pilot, 20 patients (10 control), 10 weeks | improvements in generalized pain, chronic fatigue, sleep disorders, and anxiety |
Physical therapy, exercise, and complementary interventions
Techniques such as mindfulness meditation,13 physical activity (identifier: NCT01343927), and biofeedback (JIRB N201604055) have shown promise in improving sleep quality and reducing pain in CP patients with sleep disorders. These therapies can complement conventional treatments to provide a holistic management approach. Research revealed that exercise and physical therapy improve pain and sleep quality, with regular physical activity promoting relaxation and reducing pain severity.9,13
Pharmacological interventions
Medications are frequently used to treat CP or sleep disorders, often as a first-line approach.11 Clinicians typically prioritize pain management, but concurrent treatment of sleep disorders is crucial due to their reciprocal relationship.11 To date, studies of sleep-enhancing pharmacotherapy have not consistently demonstrated improvements in comorbid CP, suggesting a potentially complex and reciprocal relationship between sleep disorders and CP.7 Many medications may alleviate pain without improving sleep or may improve sleep but fail to address pain.7
Additionally, when using multiple medications to treat CP and sleep disorders, careful management is essential due to potential interactions, risks of dependency, and decreased effectiveness.9,11 Clinicians should cautiously use medications for CP to avoid worsening sleep disturbances. For instance, opioids, commonly used for CP, can adversely affect sleep quality and duration, increasing the risk of sleep apnea and sleep-disordered breathing.14 Experts recommend using non-opioid pain relievers and tailoring medications (i.e., certain antidepressants, muscle relaxants, and melatonin) to individual needs.9,11 For managing severe chronic insomnia, melatonin, psychotropic drugs, orexin antagonists, and benzodiazepine agonists are recommended.9,11 Studies have shown that these treatments can also alleviate CP symptoms.9 For patients with prescribed opioids, clinicians should closely monitor sleep and consider alternative pain management strategies that do not compromise sleep.6
For a comprehensive review of pharmacological interventions, see the detailed review by Herrero and colleagues,15 which provides treatment recommendations that target the sleep-pain interaction.
Conclusions and prospects
CP profoundly diminishes the quality of life for millions of individuals, perpetuating a detrimental cycle where impaired sleep exacerbates pain and vice versa. This cyclical interaction underscores the need for comprehensive management strategies that address pain and sleep issues to enhance patient outcomes.
Current evidence highlights the limitations of pharmacological treatments in simultaneously addressing CP and sleep disorders. While medications may alleviate either pain or sleep issues, they often fall short of effectively addressing both. However, promising evidence supports non-pharmacological treatments, particularly CBT and physical therapy, as effective interventions for improving sleep quality and pain management. CBT-I, in particular, has demonstrated superior efficacy in managing insomnia associated with CP compared to other interventions. Physical therapy and exercise have significantly enhanced sleep quality and reduced pain severity.
Future research should further elucidate the complex mechanisms of the sleep-pain relationship. There is an urgent need to develop integrated treatment approaches that combine behavioral and physical therapies with targeted pharmacological interventions. Longitudinal studies and clinical trials exploring these multidisciplinary strategies will be crucial for advancing treatment options and improving patient outcomes in CP management.
Declaration of interests
The authors declare that the research was conducted without commercial or financial relationships that could create a conflict of interest.
Declaration of generative AI and AI-assisted technologies in the writing process
During the preparation of this work, Anja Seiger used ChatGPT and Grammarly to improve readability and language. After using this tool/service, the authors reviewed and edited the content as needed and take full responsibility for the publication’s content.
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