Insomnia in Chronic Pain Patients
William Shakespeare called sleep “nature’s soft nurse.” But this source of comfort is elusive to the patient with chronic pain.
All pain management practitioners have heard this statement: “Doctor, my pain is a lot better when I just get a good night’s sleep.” Indeed, I’ve even heard patients with chronic pain claim they don’t need daytime pain medications if they get some sleep. No wonder. During sleep, endogenous neurochemicals necessary for pain relief are replenished, and fatigued muscles get a reprieve.
It’s fair to say, however, that insomnia in patients with pain is an issue that is seldom addressed by the various pain publications and education meetings. Why? Probably because insomnia is very difficult to treat in the patient with severe, chronic pain.
We don’t fully understand the precise mechanism by which microglial activation and excess neuroinflammation lead to the imprinting of pain in the central nervous system (CNS). We clearly know, however, some of the major outcomes—constant (“24/7”) pain and severe insomnia. Another poorly understood phenomenon is dysregulation of the efferent pain signal pathways that emanate from the CNS to the periphery in central pain. With severe pain, it’s as if there is a central battery that is constantly sending pain signals into the sympathetic nervous system, keeping the patient on overload with episodes of severe allodynia (can’t touch or brush the site) and hyperalgesia (hurts excessively with pressure). The excess sympathetic discharge may manifest as tachycardia, hypertension, mydriasis, hyperhydrosis, and vasoconstriction, with cold hands and feet that may even resemble “Raynaud’s syndrome.” To top all of this off, the patient with severe chronic pain may have excess stimulation of the hypothalamic-pituitary-adrenal axis with resulting elevation of serum cortisol and catecholamines. Couple severe pain with a spine, neck, shoulder, or hip problem that won’t let you assume normal sleep posture, and you’ve got a world-class formula for misery.
Many patients, particularly those with central pain (recently called “spontaneous” pain or maldynia),1 may require potent sedatives and benzodiazepines to help them sleep; these can be misused or abused or cause oversedation and even death if not properly managed. In other words, the “burden” of treating the insomnia of intractable central pain falls directly on the physician who is already prescribing another unpopular drug class—the opioids.
Little has been written recently about treating insomnia in patients with chronic pain.2,3 Although there may have been other collective efforts to understand the impact of insomnia on patients with chronic pain, the only meaningful one I’ve encountered was a report in the Journal of the American Medical Association about a pain–sleep colloquium held at Emory University in 1999.4 The journal summarizes a few basic and fundamental aspects of sleep in patients with pain that every pain practitioner should know. About half of patients with frequent headache had a sleep-related pathology of sleep apnea, periodic limb movements, insomnia, muscle aches, and daytime sleepiness to the point of vocational impairment. About 60% of patients with arthritis claimed that “a good night’s sleep” helped them better manage their pain. Sleep and laboratory studies in patients with fibromyalgia found that they had intrusions (alpha waves) during deep sleep. Serum cortisol peaked early, causing circadian dysfunction with inducement of a pattern of going to bed too late and sleeping all morning.
Given what we know about the necessity of sleep in pain management, physicians need to treat insomnia most aggressively. Unfortunately, as noted, the pharmacologic agents that must be used to treat insomnia pose added risks in pain management, including daytime sedation, overdose, abuse, and diversion of medication. When a patient with chronic pain reports insomnia and claims that sleep helps his or her pain, however, the benefits of medical treatment most likely will outweigh the risks.
The problem of insomnia in patients with chronic pain is so universal and such a burden to the practitioner that we are addressing this critical issue in this edition of Practical Pain Management. First, the members of the PPM Editorial Board discuss their strategies for handling the dual problem of insomnia and pain. Then we present a review of pharmaceutical management of pain and insomnia, reviewing both FDA-approved treatments and over-the-counter remedies. Last, our reporters examine the nonpharmaceutical treatments of insomnia, which should provide our readers with some practical approaches to this knotty problem. We look forward to hearing if these articles help your practice.