The immune system of an older adult who doesn’t get enough sleep responds to stress with inflammation, increasing the risk for mental and physical health problems, according to researchers at the University of Rochester Medical Center.
In the study, stress led to a far greater increase in an inflammation marker in people who didn’t sleep well compared to good sleepers.
“This study offers more evidence that better sleep not only can improve overall well-being but also may help prevent poor physiological and psychological outcomes associated with inflammation,” said Kathi L. Heffner, Ph.D., assistant professor of psychiatry at the Medical Center.
The link between poor sleep and a stronger inflammatory response to acute stress could not be explained by other factors associated with immune problems, including depression, loneliness and perceived stress, said the researchers.
“Our study suggests that, for healthy people, it all comes down to sleep and what poor sleep may be doing to our physiological stress response, our fight or flight response,” Heffner said.
The study, designed to investigate stress and memory, included 45 women and 38 men with an average age of 61 years. Researchers used a standard assessment to evaluate the volunteers for cognitive status. Each participant filled out a self-report on sleep quality, perceived stress, loneliness and medication use. The volunteers had to be in good physical health, but even so, approximately 27 percent were poor sleepers.
On the day of the study, researchers gave volunteers a series of memory tests — a set of questions that served as the stressor. Blood was taken before the test began and then again immediately after the test at three intervals spaced out over 60 minutes. Researchers looked for blood levels of interleukin-6 (IL-6), a protein primarily produced at sites of inflammation.
Poor sleepers reported more depressive symptoms, more loneliness and more global perceived stress compared to people who slept well. Before the test began, poor sleepers did not differ from good sleepers in levels of IL-6. However, poor sleepers had a significantly larger increase in IL-6 in response to the stressful tests compared to good sleepers, as much as four times larger and at a level found to increase risk for illness and death in older adults.
Researchers investigated further for the potential impact of loneliness, depression or perceived stress on IL-6 levels and found no association. Poor sleep remained the predictor of higher levels of inflammation.
“We found no evidence that poor sleep made them deal poorly with a stressful situation. They did just as well on the tests as the good sleepers. We did not expect that,” Heffner said. “We did find that they were in a worse mood after the stressor than a good sleeper, but that change in mood did not predict the heightened inflammatory response.”
As people get older, there is a gradual decline in the immune system along with an increase in inflammation. Heightened inflammation increases the risk for cardiovascular disease, diabetes and other illnesses, as well as psychiatric problems.
“There are a lot of sleep problems among older adults,” Heffner said. “Older adults do not have to sleep poorly. We can intervene on sleep problems in older adulthood. Helping an elderly person become a better sleeper may reduce the risk of poor outcomes associated with inflammation.”
The study is published by the American Journal of Geriatric Psychiatry.
Source: University of Rochester