Yet another study—the first one to assess sleep and vaccine effectiveness outside of the laboratory setting—has found that sleeping fewer than seven hours a night significantly impairs the ability of the immune system to do its job. “Our study reveals the clinical relevance and role of sleep in how the immune system functions as a whole,” says Aric Prather, PhD, a 2010-2012 Robert Wood Johnson Foundation (RWJF) Health & Society Scholar at the University of California, San Francisco and Berkeley.
While many sleepers swear they do just fine on three or four hours of shut-eye a night, Prather and his team found a dramatic difference in immune response in study subjects who slept four hours to six hours, as opposed to those who were tucked in for seven to nine. In addition, “the quality of sleep did not matter. The time was the critical factor,” Prather says.
“My personal interest is in how daily stress and poor sleep work together to affect the immune system,” says Prather, an expert in psychonueroimmunology, the study of how the mind and body interact to impact immune response. “Existing sleep studies were not really telling the full story of how sleep affects the immune system, so we conducted a vaccine study to reveal the clinical relevance of sleep and show how the immune system was working as a whole. We gave 125 healthy adults, ages 40 to 60, a series of hepatitis B vaccine shots. We then looked to see how well their immune system responded by measuring their production of antibodies and whether they achieved clinical protection [an indicator of how well the vaccine was working] six months later.”
The study results, published in the article, “Sleep and Antibody Response to Hepatitis B Vaccine,” in the August 2012 issue of the journal Sleep, showed that “people who slept less produced fewer antibodies, and more surprising, those who slept fewer than six hours a night were 11 times more likely to be left unprotected from hepatitis B when they were assessed six months later,” Prather says.
Prather’s work was unique because his team measured sleep in the natural environment, rather than a sleep laboratory. This is important, Prather explains, because “while there are several laboratory studies showing that sleep deprivation disrupts immune function, these studies are difficult to generalize to what goes on in someone’s daily experience."
“We used an Actigraph, a device that monitors body movement and sleep duration, along with study subjects’ diaries on duration and quality of sleep,” he explains. “Study subjects wore the device for six nights, three prior and three following the initial vaccination, to gauge their average sleep. We also had them complete diaries for the seven days around the three vaccination periods. To measure the effectiveness of the vaccine, blood tests were performed six months after the last shot.” The study was conducted on men and women 40 to 60 years of age, because the immune system begins to work less efficiently in midlife.
“Overall, the study produced important evidence that sleep is an important immune system regulator, at least in midlife and it has some role in vaccine response, independent of other factors, such as weight and gender,” Prather says.
Prather used his protected time as an RWJF Health & Society Scholar to work on the study and “to think about how sleep and other issues might vary at the population level, or be influenced by the social determinants of health. Health & Society Scholar interdisciplinary seminars also helped me determine how to use sleep data,” Prather says.
And for those of us who toss and turn at night, Prather adds, “there are remarkably effective behavioral treatments for insomnia available at sleep centers around the country.”
The Robert Wood Johnson Foundation Health & Society Scholars program is based on the principle that progress in the field of population health depends upon multidisciplinary collaboration and exchange. Its goal is to improve health by training scholars to rigorously investigate the connections among biological, genetic, behavioral, environmental, economic and social determinants of health; and develop and disseminate knowledge and interventions that will improve health. The program is intended to produce leaders who will change the questions asked, the methods employed to analyze problems, and the range of solutions to reduce population health disparities.