Lack of sleep and pain – why exhaustion hurts

You’ve probably noticed that a lack of sleep can make you grumpy, but new research has demonstrated a clear, bidirectional association between sleep and pain, with findings indicating just one restless night can make an impact. A paper published in the Journal of Neuroscience on January 28, 2019, detailed the results of a study of 25 healthy young adults conducted by Berkeley University in California. The purpose of the study was to determine whether a lack of sleep heightened pain perception, with subjects rating the pain intensity of heat applied to their lower left legs. A baseline pain level was established for each individual at a time when they were well-rested, which was then contrasted with their experience of pain after a bad night’s sleep.

Nearly 80% of subjects experienced greater pain sensitivity after sleep deprivation. Researchers observed heightened activity in the pain-sensing regions of the brain’s cortex and reduced responsivity in the nucleus accumbens, an area of the brain’s reward circuitry that increases dopamine levels to relieve pain. Neural mechanisms that register pain and stimulate the release of the body’s natural pain killers were compromised by lack of sleep. Activity in the brain’s somatosensory cortex, which receives pain signals, increased by 126 percent following a sleepless night compared to a full night of sleep, making the difference extremely significant. In simple terms, lack of sleep was found to amplify the brain’s perception of pain and reduce its ability to cope with discomfort, meaning subjects experienced pain more intensely and had lower pain tolerance.

Recent years have seen a steady increase in the number of people suffering from chronic pain, while sleep deprivation is an established modern-day ailment bemoaned by the masses. A 2015 National Sleep Foundation poll noted one in four chronic pain sufferers were affected by a sleep disorder, compared to 6 percent of all others. Considered with the current study, a link between sleep deprivation and chronic pain cannot be discounted and warrants further investigation. To gather additional data, the Berkeley University study authors surveyed more than 230 adults of all ages about the sleep-pain connection. They found that even subtle changes in sleep patterns impacted pain the next day, either negatively when sleep was disturbed, or positively when it was restful.

As study co-author Matthew Walker, professor of neuroscience and psychology at UC Berkeley noted: “The optimistic takeaway here is that sleep is a natural analgesic that can help manage and lower pain.” How this can be achieved in a typically noisy hospital ward presents a challenge, but one worthy of thought and consideration. If a good night’s sleep could reduce consumption of pain medication, the implications for patient wellbeing may be significant.

https://news.berkeley.edu/2019/01/28/sleep-pain-connection/

https://www.sleepfoundation.org/articles/pain-and-sleep