Sleep: we all know it’s important. We all know we should be getting 7 to 9 hours a night. And yet one in five U.S. adults regularly fails to hit that target. In fact, according to the Centers for Disease Control and Prevention, one in twenty-five adults admits to having fallen asleep while driving within the last thirty days.
That’s bad news to everyone on the road, but sleep deprivation can come back to bite you even if you aren’t literally dozing off at the wheel. For instance, the next time you stub your toe. A new study from the University of Berkeley, California shows that sleep deprivation doesn’t just make you more likely to get in an accident—it actually makes the injuries from those accidents hurt worse.
How do you safely study pain in humans, especially given that everyone has a different pain threshold (and even doctors tend to underestimate the pain experienced by some groups, including women as a whole)? First, researchers applied heat to the legs of healthy students after a full night’s sleep while recording brain activity in an fMRI scanner. Students rated their personal level of discomfort on a scale of one to ten as the temperature gradually increased. On average, students said that things got dicey around 111 degrees Fahrenheit. This provided a baseline pain sensitivity for each participant.
Next, the researchers repeated the procedure after a night where the student had been unable to sleep. This time, the subjects felt the pain noticeably sooner, around 107 degrees. However, the story doesn’t end there.
By comparing the brain imaging, the scientists were able to demonstrate that the sleep-deprived brain showed increased activity in the somatosensory cortex and less activation in the nucleus accumbens and insular cortex. This suggests that the brain’s natural pain-managing mechanisms weren’t functioning as well, either.
It seems that a good night’s sleep is key to pain management—a bitter irony for anyone with chronic pain issues who’s ever attempted some peaceful shut-eye. In fact, it seems that those in pain are stuck in something of a vicious cycle: discomfort keeps you awake, and keeping you awake leads to more discomfort.
“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,” notes Matthew Walker, professor of neuroscience and psychology, and author of this study. While this research complicates our understanding of chronic pain, it does provide a way forward for the medical profession. Perhaps someday soon, hospitals will look a little more like luxury hotels, with dim lighting, comfortable beds, and restful music.
In the meantime, if you’re finding yourself nodding off in your car, it’s time to double your resolve to get more sleep at night—really, it will be better for everyone.