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Sleep-Wake Disorders and Chronic Pain: Reciprocal and Interactive Effects

Since sleep and chronic pain often co-exist, each condition should be individually recognized to assure the patient receiving attention to both the medical and mental health conditions.
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It is the classic chicken-and-egg problem: Which came first, pain or sleep disturbance. Both share common neurobiological systems, in particular, the central serotoninergic neurotransmission.1

The new Diagnostic and Statistical Manual of Mental Disorders (DSM-5) mandates that coexisting medical and mental conditions be independently specified when treating patients.2 This mandate acknowledges the bidirectional and interactive effects of coexisting medical and mental disorders.2 This conceptualization reflects a paradigm shift away from causal attributions, which is widely recognized in sleep medicine.

A sleep disorder, like chronic pain, may eventually become its own disease or centralized.3 The DSM-5 sleep-wake disorders are intended for use by general mental health and medical providers. There are 10 DSM-5 sleep-wake disorders: insomnia, hypersomnolence, narcolepsy, breathing-related, circadian rhythm, non–rapid eye movement (NREM) sleep arousal, nightmare, rapid eye movement (REM) sleep behavior, restless legs syndrome (RLS), and substance/medication-induced sleep disorders.2

Sleep-wake disorders and chronic pain often co-exist but require recognition so both are treated.

Prevalence of Sleep Problems

Insomnia is the most prevalent of all the sleep-wake disorders. It involves a subjective complaint of problems initiating and/or maintaining sleep or nonrestorative sleep. There are 4 main types of sleep problems that can occur in insomnia: delays in sleep onset, difficulty maintaining sleep, early awakening, and/or mixed. Insomnia is associated with a range of problems, including clinically significant impairment or distress in social, occupational, and other important areas of functioning.

About one-third of adults report having insomnia symptoms (approximately 10% to 20% report significant symptoms in primary care), with 6% to 10% having symptoms that meet the criteria for insomnia disorder.4 Approximately 5% to 10% of patients consulting with sleep clinics are diagnosed with hypersomnolence. It is estimated that about 1% of the US general population has episodes of sleep inertia.5 Narcolepsy-cataplexy affects less than 0.05% of the general population.6 Obstructive sleep apnea is very common, affecting 2% to 15% of middle-aged adults and more than 20% of older adults.7 Central sleep apnea comorbid with opioid use occurs in approximately 30% of individuals taking chronic opioids for nonmalignant pain and those receiving methadone maintenance therapy.8 From 5% to 10% of the night worker population is estimated to have a sleep disorder.9 The lifetime prevalence of sleepwalking in adults is 29%, with a past-year prevalence of sleepwalking of 4%.5 The prevalence of sleep terror episodes is approximately 2% in adults.10 The prevalence of monthly nightmares and frequent nightmares is 6%11 and 1% to 2%, respectively, among adults.12 The prevalence of REM sleep behavior disorder is approximately 0.5% in the general population.13 The prevalence rates of RLS range from 2% to 7%.14 Substance-induced sleep disorders can occur with alcohol, caffeine, cannabis, opioids, sedative, hypnotics, anxiolytics, amphetamines, stimulants, tobacco, and medications.2

Studies suggest that 50% to 70% of chronic pain patients suffer from a sleep disturbance,15-19 and at least 89% of patients seeking treatment for chronic pain report at least 1 complaint related to a disturbed sleep and wake cycle.20 Sleep disturbances differ according to the pain syndrome with which they are associated, and the data about these disturbances are irregular.21 People with chronic pain reported more chronic insomnia (48.6%) than did those without chronic pain (17.2%).22 At least 60% of rheumatoid arthritis patients report sleep problems, according to some data.23 Previous studies also have found increased arousals and sleep fragmentation in fibromyalgia patients compared to controls.24

Similarly, pain is influenced by the presence and type of sleep disturbance. Patients with chronic insomnia report more chronic pain (50.4%) than people without insomnia (18.2%),22 and several investigators have reported the presence of comorbid primary sleep disorders other than insomnia in patients with chronic pain conditions.25 Sleep apnea, RLS, and periodic limb movements in sleep are the most commonly cited ailments associated with pain.26 For example, sleep apnea is diagnosed in 17% of headache patients, which exceeds population rates.27

It is quite clear that pain impairs sleep. However, there is evidence of a bidirectional relationship between pain and sleep.28 Increased daytime pain is linked with poor subsequent nighttime sleep, and poor sleep is, in turn, associated with augmented next-day pain.28

How Are Sleep and Pain Related?

A typical sleep pattern can be divided into 5 stages based on brain-wave patterns from electroencephalography (EEG) ( Table 1). The first 4 stages are called non-rapid eye movement (non-REM) sleep and the last stage is called REM sleep. The sleep cycle lasts 100 minutes and recurs 4 to 6 times per night depending on the length of time one sleeps. REM periods are 10 minutes long early in the night but increase to up to 50 minutes by the end of sleep. In contrast, delta sleep is longest early in the night and shorter at the end of the night.29

Last updated on: August 16, 2017
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A Plea for Proper Opioid Tapering
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