People with high blood pressure who experience high levels of work-related stress and difficulty sleeping are up to three times more likely to die of cardiovascular disease than people with high blood pressure who don’t have either of those problems, according to a study published last week in the European Journal of Preventive Cardiology.
Although the study was conducted in Germany, its findings are also troubling for Americans. That’s because high blood pressure, work-related stress and sleep problems are all too common in the United States. Almost a third of American adults have high blood pressure, and more than a third don’t get enough sleep, government research has shown.
Job-related stress is even more ubiquitous. In a survey of American professionals taken last October, more than three-quarters of the respondents (76 percent) said stress at work was bad enough to have had a negative effect on their personal relationships, and two-thirds (66 percent) said it had caused them to lose sleep.
“Sleep should be a time for recreation, unwinding, and restoring energy levels,” said Karl-Heinz Ladwig, the German study’s senior author and an epidemiologist at the University of Munich, in a released statement. “If you have stress at work, sleep helps you recover.”
“Unfortunately poor sleep and job stress often go hand in hand, and when combined with hypertension the effect is even more toxic,” he added.
How the study was done
For the study, Ladwig and his colleagues analyzed data collected from 1,959 German workers (aged 25 to 74) who filled out health surveys between 1984 and 1995. All of the workers had been diagnosed with high blood pressure, but none at that time had cardiovascular disease or diabetes.
Questions on the surveys included ones about work-related stress and sleep problems. Based on the answers to those questions, the researchers categorized each participant as having high or low work-related stress and impaired or non-impaired sleep.
High work-related stress was defined as a job in which a high level of demands were put on the worker without giving him or her much control over decisions related to the job.
“If you have high demands but also high control — in other words you can make decisions — this may even be positive for health,” said Ladwig. “But being entrapped in a pressured situation that you have no power to change is harmful.”
Impaired sleep was defined in the study as having difficulty falling or staying asleep.
“Maintaining sleep is the most common problem in people with stressful jobs,” explained Ladwig. “They wake up at 4 o’clock in the morning to go to the toilet and come back to bed ruminating about how to deal with work issues.”
Twice the risk
The participants were followed for an average of 18 years. By the end of that period, 207 of the participants had died from cardiovascular disease, such as a heart attack, an aneurysm, a stroke or coronary heart disease.
The researchers looked to see if those deaths were associated with a high level of work-related stress and sleep problems. They found that they were. The participants who reported a combination of significant job stress and sleep difficulties at the start of the study were twice as likely to have died from cardiovascular disease than those who reported low levels of stress and no sleep problems.
That finding held even after accounting for age and various socioeconomic and behavioral factors (such as a low level of education and a sedentary lifestyle) that are also associated with an increased risk of cardiovascular disease and early death.
Limitations and implications
The study comes with several important caveats. Most notably, the study was observational and therefore can’t prove a direct causal relationship between job stress, impaired sleep and early death. The study also included a relatively small number of people — all of whom were German citizens. The findings might have been different if a larger, more diverse group of people had been followed.
In addition, the participants’ level of job stress and sleep problems were measured only once. Those people might have answered differently if asked the questions again over the ensuing years, especially since many of the people were likely to have retired during the period of the study.
Still, this study supports other findings that have found that work stress and impaired sleep are both closely intertwined with high blood pressure — as well as with an elevated risk of dying early from cardiovascular disease.
“These are insidious problems,” said Ladwig. “The risk is not having one tough day and no sleep. It is suffering from a stressful job and poor sleep over many years, which fade energy resources and may lead to an early grave.”
He and his colleagues say their study’s findings should serve as a “red flag” for doctors, one that should encourage them to talk with their patients with high blood pressure about their job strain and sleep problems.
“Each condition is a risk factor on its own and there is cross-talk among them, meaning each one increases risk of the other,” he said. “Physical activity, eating healthily and relaxation strategies are important, as well as blood pressure lowering medication if appropriate.”
He also says employers should offer stress management and sleep treatment programs in the workplace to their employees, particularly those with chronic conditions such as high blood pressure.
FMI: You’ll find the study on the website for the European Journal of Preventive Cardiology.