Shingles strikes 1 million Americans each year, causing mild to severe and even debilitating pain, according to the National Institute of Neurological Disorders and Stroke. Six percent to 70 percent of affected patients, NINDS notes, develop a chronic pain syndrome known as post-herpetic neuralgia in which shingles pain persists for months or years after other symptoms subside. In a January 2006 study in the medical journal "Pain," anesthesiologist Mark Odrcich, MD, explains that a number of explanations have emerged for why shingles becomes so painful at night.
Patients with shingles experience pain that worsens throughout the day, peaking around 8 pm when most patients are getting ready for bed, according to Odrcich. The increases are modest, but they are consistent, says Odrcich. Pain medications and antidepressants seem to decrease overall pain, but they don't affect the pattern of night time exacerbation.
Shingles pain produces associated symptoms, such as unintentional weight loss, sleeplessness, depression and disability, notes NINDS. In a December 2008 report in the "Journal of Pain and Symptom Management," psychiatrist David A. Fishbain reports that associated symptoms correlate with inadequate night time pain control and pain interference with sleep.
Mechanism of Action
Odrcich says scientists aren't exactly sure why pain due to shingles and similar conditions seems to get worse at night. Several neurotransmitters and endocrine hormones involved in pain perception exhibit diurnal variation, where morning concentrations vary inversely with night concentrations. Most important, says Odrcich, the association between time and pain exacerbation can't be attributed to stress or depression because it occurs on all days of the week, including weekends, when pain due to stress would be expected to improve. It's also seen in depressed and non-depressed patients.
In the January-February 2008 edition of "Pain Management," Pennsylvania State University pain specialist Bruce Nicholson, MD, explains that extended-release pain medications can diminish the perception of night pain due to shingles. For patients who find they wake in the middle of the night because they require additional pain medication, extended-release formulas can also improve sleep by preventing these sleep interruptions. Nicholson specifically recommends tramadol, a generic prescription opioid pain medication.
In May 2006, the Food and Drug Administration approved a live virus vaccine, Zostavax, that prevents shingles in up to half of treated patients and significantly reduces pain and postherpetic neuralgia among those who still develop the disease. The major side effect of the vaccine is mild injection-site swelling and tenderness, which occurs in up to 48 percent of patients, according to the FDA. However, notes NINDS, the vaccine has only been approved for people older than 60 who have not already had shingles.
- National Institute of Neurological Disorders and Stroke: Shingles: Hope Through Research
- “Pain”; Chronobiological Characteristics of Painful Diabetic Neuropathy and Postherpetic Neuralgia; M. Odrcich et al.; Jan. 2006
- “Pain Practice”; Benefits of Extended-Release Opioid Analgesic Formulations in the Treatment of Chronic Pain; B. Nicholson; Jan.-Feb. 2009
- “Journal of Pain and Symptom Management”; Does Pain Mediate the Pain Interference with Sleep Problem in Chronic Pain?; D.A. Fishbain; Dec. 2008
- Food and Drug Administration: Zostavax: Zoster Vaccine Live