Obstructive sleep apnea (OSA) is associated with numerous comorbid conditions. In many, a causative relationship has either been well established or strongly associated. As the knowledge of sleep-disordered breathing and its consequences continues to grow, so does the list of associated or consequential conditions. This article is part 2 of a 5-part series exploring more recently identified consequences of OSA.
Chronic pain has become the most common reason for outpatient medical visits. Treatment of chronic pain syndromes and the habitual use of opioids have dramatically increased in the past 2 decades. Between 1990 and 1996, the long-term use of oxycodone increased by 23%, hydromorphone use increased by 19%, morphine use increased by 59%, and the use of fentanyl increased 1168%.[2,3,4] This dramatic rise in habitual narcotic use has continued, and the long-term use of opioids more than doubled from 2000-2008.[2,3,4]
A bidirectional relationship exists between pain and sleep disturbances. Pain fragments sleep continuity, impairs sleep quality, and disrupts normal sleep architecture. Reciprocally, poor quality or insufficient quality of sleep may decrease the pain threshold, impair recovery from injuries, or further exacerbate the pain response. Painful stimuli produce microarousals, which disrupt sleep continuity and alter normal sleep. Chronic pain is associated with increased high frequency EEG activity and a decrease in slow frequency EEG activity. Furthermore, chronic pain is associated with the appearance of alpha waves superimposed on slower EEG frequencies, or "alpha-delta" sleep.[5,6] In short, pain produces a state of shallow sleep while disrupting restorative slow-wave sleep.
An estimated 28 million Americans have sleep complaints due to chronic pain syndromes. Among patients with chronic pain, more than 50% experience sleep disturbances. Some reports say as many as 70%-88% patients with chronic pain report sleep trouble.[6,7] Sleep disturbance shows an independent and linear correlation with pain severity, even after controlling for health measures and sleep habits.
Sleep complaints portend worse outcomes among those with chronic pain. Compared with patients who have no sleep complaints, patients with chronic pain and insomnia report poorer quality-of-life indices and have increased healthcare utilization.
In patients with fibromyalgia, complaints of poor sleep quality and fatigue are more prominent than pain.[8,9] Similar to other conditions, sleep quality and the pain response share a reciprocal cause-and-effect relationship. Among patients with fibromyalgia, a poor night's sleep predicts more pain the next day, and more pain predicts greater sleep impairment that night. Patients with fibromyalgia frequently experience nonrestorative sleep and alpha-wave intrusions are commonly observed during polysomnography. The prevalence of insomnia, restless legs syndrome (RLS), and hypersomnia are higher among patients with fibromyalgia than within the general population. Similarly, OSA is significantly more common, with observed rates of 46%-80% reported among patients with fibromyalgia.
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Cite this: The Association of Obstructive Sleep Apnea and Chronic Pain - Medscape - May 24, 2013.