Sleep and Pain

Valerie McLaughlin Crabtree, Amanda M. Rach and Merrill S. Wise

Introduction

Chronic pain, described as pain occurring for 3 months or longer, is a relatively common condition and is reported to affect up to 44% of children and adolescents, with higher rates of chronic pain reported in girls beginning at age 4.¹ Many chronic pain conditions – including fibromyalgia, rheumatologic disorders, and other causes of musculoskeletal pain, functional abdominal pain, headaches and migraine, cancer, and spasticity-related pain in cerebral palsy – have been linked to both disturbed sleep and daytime fatigue in children and adolescents. In fact, approximately half of all pediatric pain patients report disturbed sleep.^2–7 In a sample of adolescent patients with chronic pain, reports of insomnia were six times higher than in the healthy adolescent population.⁶ Poor sleep is also associated with episodic acute pain, as is commonly seen in many conditions including sickle cell disease.^8,9 A disturbance of sleep in children and adolescents with pain has been demonstrated convincingly through the use of self- and parent-reports, diary methodology, and actigraphy; far fewer studies have utilized polysomnography (PSG). It is likely that chronic pain and related sleep disturbances in children also have a strong negative impact on the sleep and quality of life of parents and caregivers, although this has not been carefully investigated.

This chapter will explore the consistent finding that sleep is disrupted in children and adolescents with pain, and it will examine it from the perspective that a bi-directional relationship exists between pain and sleep.¹⁰ Additionally, we will review more recent investigations that examine the mediating and moderating impact of mood on the relationship between pain and sleep and on the functional impact of this relationship on children and adolescents. Not only is sleep disrupted in children and adolescents with chronic pain, but daytime fatigue and reduced health-related quality of life are present in this population as well. Finally, there will be a discussion of pharmacologic and non-pharmacologic interventions designed to ameliorate sleep disturbances and, when possible, to diminish pain.

Chronic Pain

The most frequent sleep-related complaints in youth with chronic pain are: difficulty initiating and maintaining sleep, difficulty awakening in the morning, daytime sleepiness, napping, snoring, and nightmares.4–6,11 Poor sleep in children with chronic pain has a significant negative impact on health-related quality of life through such pathways as activity limitation and functional disability.^5,12 Adolescents, for example, with poor sleep quality, poor sleep efficiency, and difficulty initiating and maintaining sleep have more limited daytime activities than do adolescents with chronic pain who do not have poor sleep – even when controlling for pain and mood disturbances.¹² These observations highlight the importance of understanding the role of disturbed sleep in pediatric pain patients instead of solely attributing daytime activity limitations and poor quality of life to chronic pain. Furthermore, levels of pre-sleep cognitive arousal and sleep-related anxiety are reported to be higher in youth with chronic pain and are predictive of reports of insomnia.^4,6 This anxiety – likely reflecting intrusions of worry or anxiety related to pain and functional limitations – also interferes with sleep onset and lends itself to implementation of cognitive-behavioral interventions for insomnia.

Acute Pain

Although the majority of reports in the literature on sleep and pain focus on the relationship between sleep disturbance and chronic pain, acute pain is also known to disrupt sleep. Post-surgical pain, acute injury, or dental pain, for example, may negatively impact sleep, and such painful occurrences are typically part of all children’s lives on occasion. Acute pain may disrupt sleep directly, or it may do so indirectly through efforts to reposition or mobilize during sleep. In some cases the psychological impact of a traumatic event that caused the acute pain may contribute to sleep disturbance as well.¹⁰

Methods of Sleep Assessment

Evaluation of the child with pain and sleep issues begins with a thorough history. The healthcare provider should try to understand and characterize the child’s pain and other medical issues as well as taking a careful sleep history. Ideally, the clinician should possess a thorough understanding of normal sleep physiology in children and must be willing to devote time to eliciting the history directly from the child, whenever possible, as well as from the parent or caregiver. In addition to typical details, such as bedtime routines, habitual bed and rise times, and sleep continuity, the clinician should ask about sleep quality during the night, the degree of restoration after the major sleep period, possible sleep-related breathing problems, symptoms of restless legs syndrome and periodic limb movements, and parasomnias (sleepwalking, sleep talking, sleep terrors, and sleep bruxism). Obtaining a history of nap frequency is important, as is other evaluation of alertness or sleepiness during the day. Parents should be asked their perceptions about the associations among nocturnal pain, sleep quality, and daytime function. A thorough medication history is also important, especially since children with chronic or acute pain are likely to be taking several. Questions about mood, emotional regulation, and anxiety should not be forgotten and lead further toward a comprehensive understanding of the child’s sleep.

Both subjective and objective means of assessment are helpful in children with chronic pain. Subjective measures range from single time point self-report questionnaires to daily diary methods filled out over weeks or months. Depending on the age and ability of the child, measures can be completed by the child, the parent, or (ideally) by both. Within pediatric sleep research, parents are often the primary source of information; however, results of Valrie et al. suggest retrospective and concurrent reports by child and parent show adequate correspondence.⁸

Because interviews, questionnaires, and diaries are subjective, they are more appropriate to assess perception and awareness of sleep behaviors (night wakings, resistance to sleeping alone, sleepwalking, night terrors, snoring, restless and disrupted sleep, and apneic pauses) than are objective measures of sleep.¹³ Objective data are also critical to obtain, for obvious reasons. The most commonly used objective methods are actigraphy and polysomnography (PSG), with videography growing in usage. Objective measurement periods can last from 1 day (PSG) to up to several weeks (actigraphy) and are best used to assess amount and timing of sleep (PSG or actigraphy) and stages of sleep, sleep quality, and causes of disrupted sleep (such as sleep apnea, periodic leg movements, parasomnias, or seizures) (PSG).¹⁴ Since methods vary in terms of duration, effort, cost, and reliability, the use of multiple measures is helpful when feasible.

Self-Report Questionnaires

The multifaceted nature of sleep has led to the development of questionnaires assessing sleep patterns and habits, symptoms of disrupted sleep, and thoughts or beliefs about sleep (Tables 12.1a, 12.1b). Although most questionnaires assess sleep retrospectively (typically over the preceding 1–4 weeks), some inquire about current sleep on a night-to-night basis;¹⁵ thus, care should be taken when selecting a measure for a particular purpose and population.

Table 12.1a

Parent Report Measures of Sleep Used in Chronic Pain Populations

Children’s Sleep Hygiene Scale; CSHS⁷⁹	17 item; 2–8 years	Activities surrounding sleep such as bedtime routines, stable bedtime and wake times over the past month
Children’s Sleep Habits Questionnaire; CSHQ^75,81	35 item; 4–10 years	Behavioral and medical-based sleep problems over the last week
Children’s Sleep Wake Scale; CSWS⁸⁰	40 item; 2–8 years	Child’s sleep over the last month in the areas of going to bed, falling asleep, awakening, reinitiating sleep, and wakefulness
Sleep Disturbance Scale for Children; SDSC⁸²	26 item; 5–15 years	Sleep initiation and maintenance, daytime sleepiness, sleep–disordered breathing, and sleep arousal
Epworth Sleepiness Scale; ESS⁸⁵	8 item; 2–18 years	Assess daytime sleepiness, falling asleep during daytime activities

Table 12.1b

Child Self-Report Measures of Sleep Used in Chronic Pain Populations

Sleep Habits Survey; SHS⁵⁹	36 item; 10–19 years	Usual sleeping and waking on school and weekend nights, school performance, daytime sleepiness, and sleep–wake behavior problems past 2 weeks
Sleep Self Report; SSR⁷⁵	18 item; 7–12 years	Sleep habits, problems falling asleep, sleep duration, night waking, and daytime sleepiness past week
Adolescent Sleep Hygiene Scale; ASHS⁸³	28 item; 12–18 years	Sleep-facilitating and sleep-inhibiting practices on 9 domains over the last month
Adolescent Sleep Wake Scale; ASWS⁸³	28 item; 12–18	Assesses sleep initiation, maintenance, and quality across five dimensions in the past month
Pre-sleep Arousal Scale; PSAS⁸⁴	16 items; 12–18 years	Cognitive and somatic arousal prior to sleep onset
Epworth Sleepiness Scale; ESS^85,86	8 item; 2–18 years	Assess daytime sleepiness, falling asleep during daytime activities

Despite the inherent limitations associated with self-report questionnaires, their low cost and ease of implementation make them the most commonly used method in research with pediatric pain patients. Studies comparing the accuracy of self-reports to objective measures have found acceptable levels of agreement on certain sleep markers (total sleep time, sleep quality); however, parents sometimes tend to underreport the prevalence of night awakenings.16,17

Self-Report Daily Diaries

Prior to the development of actigraphy and PSG, daily diaries were considered the gold standard for sleep assessment in both adults and children.¹⁸ More recently, studies found acceptable reliability and validity when child-completed daily sleep logs were compared against objective measures (actigraphy).^19,20 Sleep diaries are completed upon awakening and may capture much information including: bedtime, wake time, planned wake time, elements of sleep quality, number of perceived night wakings, time from lights out to sleep onset (sleep latency), time awake between sleep onset at night and time of rising in the morning (wake after sleep onset (WASO) ), and other relevant information such as where the child slept, medications taken prior to bed, and bedtime difficulties.^21,22 Daily diaries have provided a unique methodology for elucidating the bi-directional relationship between pain and sleep in pediatric patients, which will be discussed later in this chapter.9,23

Actigraphy

An actigraph is a wristwatch-sized instrument usually worn on the non-dominant hand or ankle that measures movement over time and uses this as an indirect measure of sleep and wakefulness.¹⁵ Some models include an event button that can be pressed to signal bedtime and morning waking. The actigraph can be worn 24 hours a day for many days, and it captures data while the child sleeps in his or her normal environment.^24–28 Actigraphy records sleep parameters such as total sleep duration (from sleep onset to final waking), sleep onset latency (minutes from bedtime to the first 20-minute period of sleep), total time in bed (from lights out to got out of bed events), and sleep efficiency (ratio of total sleep duration to total time spent in bed).²¹ Actigraphy has been deemed useful for characterizing and monitoring circadian rhythms and sleep disturbances in children by the Standards of Practice Committee of the American Academy of Sleep Medicine (AASM),²⁹ and it has been successfully used to measure the sleep patterns of children and adolescents experiencing a range of chronic pain conditions including migraine,²¹ recurrent abdominal pain (RAP),³⁰ and chronic musculoskeletal pain.³¹

The majority of actigraphy studies suggest that children and adolescents with chronic pain have sleep patterns similar to their peers without pain. Children and adolescents with RAP, as well as those with migraines, demonstrated no group differences in sleep duration, WASO, and sleep efficiency compared to control groups.21,30 However, adolescents recruited from a multidisciplinary pain clinic had similar total sleep times but lower sleep efficiencies and more night wakings compared to a pain-free control group.³² Further, a 2008 study of 17 females with chronic musculoskeletal pain found that the majority of participants experienced disturbed sleep with reduced nighttime sleep, increased nighttime wakefulness, and decreased sleep efficiency.³¹

A 2010 study by Lewandowski et al.,¹⁵ investigating the relationship between pain and sleep, reported results similar to the 2004 studies by Haim et al.³⁰ and by Bruni et al.²¹ Adolescents receiving treatment for chronic pain did not differ from a sample of peers with intermittent pain complaints on measures of average sleep duration, sleep efficiency, or WASO. Across both groups, longer sleep durations were associated with increased next-day pain in both chronic and occasional pain sufferers. Interestingly, increased sleep duration was not associated with self-reported higher levels of sleep quality, sleep efficiency, or restorative sleep.¹⁵