Postoperative pain is exacerbated by lack of sleep prior to surgery, new research suggests. But it's not all bad news, because the study also found that caffeine could help to counteract this effect.
Study co-author Dr. Giancarlo Vanini, of the Department of Anesthesiology at the University of Michigan in Ann Arbor, and colleagues recently reported their findings in the journal Sleep.
Studies suggest that over 80 percent of patients who undergo surgery experience acute pain following the procedure, and around 75 percent report the pain as being moderate, severe, or extreme.
Previous research has suggested that insufficient sleep before and after a surgical procedure may increase postoperative pain severity.
"However, while the relationship between sleep and pain is well known, its underlying mechanisms remain unclear," notes Dr. Vanini.
Sleep, surgical pain, and the brain
For this latest study, Dr. Vanini and colleagues sought to gain a better understanding of how a brief period of sleep deprivation prior to surgery might influence postoperative pain and recovery.
Furthermore, the team investigated whether caffeine - a known stimulant - might help to reduce postoperative pain triggered by lack of sleep.
To reach their findings, the researchers made a surgical incision in the paws of male and female rats, some of which were sleep-deprived immediately before the procedure.
Results revealed that the sleep-deprived rats were much more sensitive to pain following surgery and took longer to recover, compared with rats who had sufficient sleep prior to the procedure.
Interestingly, the team found that pharmacologically blocking receptors for adenosine - which is a neurotransmitter involved in sleep regulation - in the hypothalamus brain region of the rats reduced the effects of sleep deprivation on postoperative pain.
"These results identify a brain region, neurotransmitter, and receptor mechanism that might contribute to regulate the relationship between sleep, wakefulness, and pain," say the researchers.
Caffeine reduced sleep-related surgical pain
The researchers then tested the effects of caffeine - which studies have shown can block adenosine receptors - on rat models of postoperative pain.
They found that caffeine reduced post-surgery pain, but only for rats that experienced sleep deprivation prior to surgery.
"We think that caffeine might prevent the increase in pain sensitivity by blocking part of the neurochemical changes induced by sleep deprivation in specific brain areas that control sleep and wakefulness, and project to pain-related sites," says Dr. Vanini.
While further studies are needed to confirm the findings, the researchers believe that they highlight the importance of getting a good night's sleep prior to undergoing a surgical procedure. In the likely event of sleep deprivation, however, could a cup of coffee help?
"This study suggests a novel intervention with potential to significantly improve postoperative pain management in clinical settings. We now look forward to testing whether caffeine is effective to reduce pain in surgical patients."
Dr. Giancarlo Vanini