For instance, people who develop chronic pain often lose the ability to sleep well, and quickly point to a bad back, sciatica or arthritis as the reason. The loss of sleep, in turn, can make a bad back feel worse, and the next night’s slumber even more difficult.
Why sleep deprivation amplifies pain is not fully worked out, but it has to do with how the body responds to an injury such as a cut or turned ankle. First, it hurts, as nerves send a blast up the spinal cord and into the brain. There, a network of neural regions flares in reaction to the injury and works to manage, or blunt, the sensation.
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Think of the experience as a kind of physiological dialogue between the ground unit that took the hit and the command centre trying to contain the damage. In a new study, a team of neuroscientists has clarified the nature of the top-down part of that exchange, and how it is affected by sleep.
In a sleep-lab experiment, the researchers found that a single night of sleep deprivation reduced a person’s pain threshold by more than 15 per cent and left a clear signature in the brain’s pain-management centres.
In a separate experiment, the team determined that small deviations in the average amount of sleep from one day to another predicted the level of overall pain felt the next day.
“What’s exciting about these findings is that they will stimulate, and justify, doing more research to figure this system out,” said Michael J Twery, director of the sleep disorders branch of the National Heart, Lung and Blood Institute, who was not involved in the new study.
“Once we understand how sleep deprivation changes how these pathways function, we should be able to manage pain more effectively – all types of pain.”
Other researchers cautioned the study was small, and needed larger replication. But, they said, at a time when chronic pain conditions and narcotic addiction are on the rise, the new work is a pointed reminder that the body’s own ability to manage pain can be improved without a prescription.
The study team, led by Adam J Krause and Matthew P Walker of the University of California, Berkeley, had 25 adults come into the lab on two occasions to measure their pain threshold for heat.