US workers who clock more than 51 hours a week -- particularly those in clerical or unskilled positions -- are 29 percent more likely to have high blood pressure than those who work 39 hours or less, new research has found.

Haiou Yang, PhD, along with Dean Baker, MD, MPH, and colleagues at the University of California in Irvine evaluated data from a representative sample of 24,305 California adults who worked 11 hours or more each week. Information was obtained through a telephone survey conducted in 2001.

Even after adjusting for other contributing factors such as socioeconomic status and body weight, the researchers found that the likelihood of having hypertension coincided with the number of hours worked.

The individuals who worked 39 hours or less were least likely to have high blood pressure, with those who worked 40 hours per week 14 percent more likely than to be hypertensive. The risk increased to 17 percent higher for people who worked 41 to 50 hours weekly, and 29 percent higher for those who put in 51 hours or more.

Clerical and unskilled laborers were more likely to have high blood pressure than professionals, suggesting that mental challenge might protect against hypertension, the article states.

Yang and colleagues pointed out that most of the past research on work hours and hypertension has been conducted among Asian workers. In Japan, the term "Karoshi" means "sudden death from overwork." Although Japan has a reputation for having a high-pressure working environment, Americans currently work longer hourse, on average, than the Japanese do.

In fact, the US stands out as one of the few developed countries in the world that does not have laws restricting work hours.

Individuals can take steps to prevent high blood pressure by adopting a healthy lifestyle, advises the National Heart, Lung and Blood Institute: