New research from the University of California at Berkeley shows the body’s ability to manage pain is controlled in part by the amount of sleep it gets. The study findings published in the Journal of Neuroscience shed some light on the self-perpetuating problem of chronic pain and sleeplessness that in part contributes to opioid addiction.
The problem of sleep loss is two-fold – it increases the body’s pain sensitivity and decreases the body’s natural painkilling response. This creates a vicious cycle that continues as long as the pain is present because pain can cause people to lose sleep and the loss of sleep can cause people to experience more pain.
This research seems to confirm a 2015 National Sleep Foundation poll in which two-thirds of respondents with chronic pain reported having reoccurring sleep disruptions.
"If poor sleep intensifies our sensitivity to pain, as this study demonstrates, then sleep must be placed much closer to the center of patient care, especially in hospital wards," said study author Matthew Walker.
Walker and fellow researcher Adam Krause scanned the brains of healthy study participants while applying uncomfortable amount of heat to their legs. They compared the body’s response when fully rested and sleep deprived and found an increase in pain sensitivity during sleep loss.
"Sleep loss not only amplifies the pain-sensing regions in the brain, but blocks the natural analgesia centers, too," Walker said.
The scientists found a decrease in the level of activity in the nucleus accumbens, a region of the brain that, among other things, increases dopamine levels to relieve pain. They also saw less of a response in the insula region of the brain of the sleep-deprived. That region is responsible for evaluating pain signals and putting them in context to prepare the body to respond.
"This is a critical neural system that assesses and categorizes the pain signals and allows the body's own natural painkillers to come to the rescue," Krause said.
"The optimistic takeaway here is that sleep is a natural analgesic that can help manage and lower pain," Walker said. "Yet ironically, one environment where people are in the most pain is the worst place for sleep—the noisy hospital ward. Our findings suggest that patient care would be markedly improved, and hospital beds cleared sooner, if uninterrupted sleep were embraced as an integral component of healthcare management."