Learning Objectives: After participating in this continuing professional development activity, the provider should be better able to:

1. Describe the relationship between sleep and pain and the prevalence of sleep problems in patients with chronic pain.

2. Delineate areas of risk assessment of sleep disturbance in clinical practice.

3. Explain basic sleep hygiene practices that can be incorporated into pain management.

Pain is the most common cause of disability in the United States,1 and it costs more than $650 billion in medical expenses, economic loss related to disability days, and lost wages and productivity.2 A recent National Health Interview Survey (2019) demonstrated that 50.2 million adults reported having pain every day or most days, with pain in the back, hip, knee, or foot being the most common.3 Among the multiple approaches needed to manage pain, sleep hygiene is one that has clearly provided a benefit to not only pain, but to overall wellness. The purpose of this article is to discuss the evidence in the literature on the relationships between sleep and pain and then provide a sleep risk assessment tool and sleep management approaches that can help clinicians guide their practice.

Chronic pain is pain that "persists for 12 weeks or longer, even after an initial injury or underlying cause of acute low back pain has been treated."4 Chronic pain is a public health concern and 22% of the primary care appointments focus on pain management.5 The cost of managing chronic pain is escalating in the United States and at a global level.

Chronic pain is a complex condition and not just one symptom. It is a multidimensional disorder constituting various physiological, psychological, behavioral, and social factors.6,7 Among physiological factors, sleep has been shown to be one of the most challenging for patients to manage. Managing chronic pain is complex, and clinicians find it difficult to address all the accompanying psychological, physiological, and biobehavioral factors to help patients to better cope with chronic pain and improve their quality of life. Among all other lifestyle habits, sleep habits are crucial to improving quality of life in patients with chronic pain.

Pain and Sleep

Sleep is a basic human need. There is clear evidence that lack of sleep affects pain in many ways. Although earlier studies demonstrated a clear effect of sleep deprivation on pain perception in animals, data in humans at that time were not conclusive.8 However, there is evidence of the hyperalgesia effect of deprivation of sleep in both animals and humans.

A mouse model demonstrated that sleep deprivation heightened the physiological and behavioral response to musculoskeletal sensitization9 Other studies of experimental sleep deprivation in human subjects demonstrated that sleep deprivation enhanced pain.10,11 Sleep loss reduces the threshold for pain perception in adult human subjects.12 Cross-sectional studies of healthy subjects suggest that pain disturbs sleep quality and continuity, and that poor sleep further exacerbates pain.13

One meta-analysis that quantified the effect of sleep deprivation in healthy human subjects on pain perception revealed a medium effect size (standardized mean difference = 0.62).14 A systematic review conducted in 2014 demonstrated evidence on the effect of sleep deprivation in animal and human models.15 More importantly, a review focusing only on controlled trials reported conclusive evidence of a decrease of pain thresholds and an increase in bodily complaints after sleep deprivation.16

Multiple studies have confirmed a bidirectional relationship between sleep disturbance and pain intensity, which indicates that pain may lead to sleep disturbance and that poor sleep may cause or worsen pain.17

For example, in clinical trials, patients reported less pain sensitivity when they were effectively treated for sleep disorders such as restless leg syndrome and obstructive sleep apnea syndrome.18 Also, pharmaceutical studies have shown that medications used to treat insomnia (eszopiclone, triazolam) result in improvement in sleep and decreased pain intensity.19 Further, in a longitudinal study, it was demonstrated that a night of poor sleep quality was followed by a day with more severe pain, which consequently worsened sleep quality during the subsequent night.20

A systematic review reported that greater pain severity and pain interference with activities were related to sleep disturbance, lower sleep quality, and feeling less rested.21 All together, these findings suggest that lack of sleep results in greater sensitization of pain pathways, and greater perception of pain; yet precise sleep assessment methods are unclear.

Chronic Pain and Sleep Disturbance

Sleep is needed for growth, tissue restoration, and energy conservation.22,23 In healthy individuals, sleep disturbance occurs occasionally. A person might have trouble falling asleep or fall back to sleep after waking up during the night for a few nights. However, it is only natural to expect that pain will affect sleep in patients with chronic pain.

There are various sleep disorders (not limited to narcolepsy, insomnia, and sleep apnea) that have been studied within the pain literature, but sleep disturbances and insomnia are the most studied in chronic pain.

About 50% to 88% of patients with chronic pain also suffer from sleep disorders,24-26 and more than 40% patients with insomnia also have a diagnosis of chronic pain.27 For example, chronic musculoskeletal pain, including arthritis, low back pain, and fibromyalgia, is often associated with insomnia.28,29

An epidemiologic study highlighted poor sleep quality as an independent risk factor for developing chronic pain, especially musculoskeletal pain.30 Sleep disturbance is strongly associated with fatigue, daytime sleepiness,31 more severe pain,32 psychological distress, physical disability,33 and more hospitalization for low back pain compared with people with no sleep problems.34

Moreover, sleep disturbance in chronic pain may be attributable to pain itself. In contrast to the traditional belief that pain severity can predict severity of sleep disturbance, studies show that enhanced pain perception can also be due to sleep disturbance, resulting in a vicious cycle. Although the above studies address the impact of sleep disturbance on pain, there is need for a change in assessment and treatment of these symptoms using a whole person-centered approach. A sleep risk assessment tool that can be used by clinicians to assess needs for providing education on sleep hygiene practices will be discussed.

Risk Assessment of Sleep Disturbance

As discussed previously, there is abundance of evidence on the coexisting sleep problems in chronic pain, but it is often overlooked by health care providers.35 As scientists continue to study the intricacies behind sleep,36,37 there are challenges that remain not only due to lack of specific biomarkers to assess sleep,38,39 but also a dearth of convenient, reliable, and affordable methods35 to measure sleep in chronic pain.

In the past 2 decades, there has been a growing interest in developing and validating new sleep measures to test sleep disorders in different populations. Measures include the sleep symptoms checklist40; Auckland Sleep Questionnaire41; Global Sleep Assessment42; Holland Sleep Disorders Questionnaire43; Iowa Sleep Disturbances Inventory44; and SLEEP-50 questionnaire45; and Pittsburgh Sleep Quality Index (PSQI).46

Sleep diaries are patient-reported tools, whereas wrist actigraphy and polysomnography are objective sleep measures.47 The sleep diary is considered a gold standard subjective measure and polysomnography is the gold standard among objective measures. Because it captures daily variations,48 sleep diary may be closer to objective measures like wrist actigraphy.49 Wrist actigraphy is an objective measure that has been frequently used to study sleep parameters across various populations. There are differences between the sleep diary and wrist actigraphy, particularly in that the wrist actigraphy lacks the cognitive component of subjective measures.50

In clinical practice, one option is to ask the patients to complete the PSQI at the time of initial visit and then ask patients to complete a sleep diary for a week before they come for a follow-up visit on a regular basis.

The sleep diary can also be completed by patients upon waking for up to 7 nights. Patients can be asked to record the time they went to bed, the time it took to fall asleep, time they woke up, amount of time awake after initially falling asleep, number of awakenings during night, and total amount of sleep obtained. Patients could also be asked how they would rate their quality of sleep on a scale of 1 to 9 (1 = terrible, 9 = great) and how rested they felt after waking up in the morning, on a scale of 0 to 4 (0 = not at all, 4 = extremely).

Upon looking at the scores from any of these tools, the clinician can identify whether the patient is having sleep problems. However, one should not think that pain is the only cause of a sleep problem in someone with chronic pain. There are various reasons an individual might have difficulty with sleep. Although it is important to use these tools in practice, given the cost of some measures, and time needed for completing these tools, a viable option is to include a sleep risk assessment tool for assessing sleep problems when patients come for their follow-up visit for chronic pain management.

As there is enough evidence of the need for addressing sleep disturbance in patients with chronic pain, it is therefore a matter of purposefully identifying, during clinic visits, those patients at risk for sleep disturbance.

Although sleep measurement tools identify sleep quality and sleep disturbances, they do not assess sleep habits or sleep hygiene practices that the patient might or might not be incorporating into their daily routine. Therefore, it is crucial to screen patients on their sleep habits during every visit by using sleep risk assessment tools along with pain assessment. It might be feasible for clinicians to use a simple screening tool to identify whether the patient is in fact at risk for having poor sleep quality.

The benefits of sleep hygiene practice have been well established in the literature and include: following a routine for bedtime including going to bed at the same time each night; waking up at the same time; getting enough sunlight when possible during the day; avoiding caffeinated drinks and alcoholic beverages in the afternoons after 3 pm; being active in the mornings and relaxing in the evening hours; keeping the bedroom environment quiet and dark with appropriate temperature, and avoiding stimulus from bright lights or electronics.

Current clinical practice recommendations are to incorporate sleep risk assessment tools during pain assessment. Unless asked specifically, patients usually do not mention that they have sleep disturbance. One possible reason is that patients might think that if their pain is better managed, they should then be able to sleep better without sleep disturbance.

Another possibility is that patients might consider the clinician as someone whom they value as having expertise in addressing their symptoms using a medical model of approach. However, there is a need to incorporate changes in practice by identifying behaviors that could be attributed to sleep problems.

Below is a potential sleep risk assessment tool that can be used in practice when patients come for pain management. All patients can be given this tool to assess whether they are at risk for sleep problems.

Table 1 provides details of the RACE sleep risk assessment tool. Based on this tool, we can classify patients who come into the clinic for pain management as having high risk for sleep problems when they score in the range of 7 to 10, moderate risk at 4 to 6, and lower risk at 0 to 3. Such an approach might be one step closer to looking at the patient from a whole-person-centered approach rather than a unimodal approach.

Table 1. RACE Sleep Risk Assessment Tool

Sleep Management Approaches for Chronic Pain

Behavioral and psychological treatments are gaining momentum in finding effective sleep interventions for chronic insomnia disorders in adults. Some of these behavioral and psychological treatments include cognitive behavioral therapy (CBT), paradoxical intention, stimulus control, sleep restriction therapy, relaxation training, sleep hygiene, biofeedback, intensive sleep retraining, and mindfulness.51

There is clear evidence that CBT is effective for patients who have comorbid insomnia and chronic pain. A systematic review based on 14 randomized controlled trials reported that CBT significantly improved sleep and also reported that there was a probability of 81% and 71% for better sleep after CBT at posttreatment and final follow-up, respectively.

Several other studies on various types of chronic pain have also reported the effectiveness of CBT on comorbid insomnia and chronic pain52-54 and insomnia caused by chronic pain.55 Mindfulness-based interventions are also showing to be effective in some studies for improving overall quality of life in patients with chronic musculoskeletal pain.56,57

Sleep hygiene by itself has not been incorporated as an intervention for sleep problems in chronic pain. However, in chronic insomnia, a few studies have demonstrated beneficial effect of sleep hygiene therapy, but to date, there is not sufficient data to evaluate the efficacy of treatment, due to the varying methods of delivery and varying patient populations.58,59

Many recommendations such as stimulus control, sleep hygiene, and relaxation therapy have also been recommended to improve sleep and reduce insomnia.60 Practicing good sleep hygiene, such as avoiding frequent daytime napping, late evening exercises, smoking in the evening, late heavy dinner, and spending too much nonsleep time in bed have been recommended to be included.61,62

Conclusion

Based on the evidence and extensive research reviewed in this article, the time is ripe for making some interventions in practice to help patients who have chronic pain and comorbid sleep problems.

Targeting sleep hygiene practices includes assessing sleep behaviors and psychosocial and environmental factors that can affect sleep and thereby improve pain in patients with chronic pain. Groups sessions, interactive apps, pamphlet materials, and therapy sessions can be potential ways to engage patients in improving their sleep habits. Based on the RACE tool, once sleep risk assessment is identified, sleep hygiene education can be implemented based on the scores. However, if sleep hygiene scores are higher, then the clinician might have to identify whether pain is the main cause of sleep problems and/or whether other behavioral symptoms such as depressive mood, fatigue, or anxiety might be adding to the sleep problem.

Although addressing the person as a whole is the most important step for a holistic management of pain and sleep in patients with chronic pain, incorporating the sleep assessment tool could be a step toward a comprehensive pain management approach.

References