The majority of research previously done on the connection between long working hours and hypertension has usually focussed on Asian workers, in particular the Japanese,whose high work pressure ethos has resulted in the phenomenon known as Karoshi, or 'sudden death from overwork'.

But in recent years the average work load in the States has increased and now Americans work longer hours than the Japanese do.

In order to find out if longer working hours had any impact on blood pressure Dr. Haiou Yang of the University of California in Irvine and colleagues examined a representative sample of 24,305 California adults who worked 11 hours or more each week.

The team found that those who worked 40 hours per week were 14 percent more likely to have high blood pressure than people who worked 39 hours or less, and the risk for hypertension was 17 percent greater in those working 41 to 50 hours weekly, and 29 percent higher in those working 51 hours or more.

The researchers say the risk of having high blood pressure rose steadily with the number of hours worked and persisted even after adjusting for factors such as socioeconomic status and body weight.

It was also found that hypertension was more common among clerical and unskilled workers than among professionals and they believe this suggests that occupations requiring more challenging and mentally active work may have a protective effect against hypertension.

It is interesting to note, say the researchers, that most developed countries have legislation limiting work hours, except for the United States.

Meanwhile scientists at Harvard University have come up with a list of 10 ways of getting and keeping blood pressure under control.

They say the first step is to check your blood pressure on a regular basis so you know your situation;

exercise as this can lower blood pressure by 10 points; eat a diet which is rich in fruits, vegetables, low-fat dairy products, whole grains, poultry, fish, and nuts; lose weight if you are overweight; don't smoke as smoking one cigarette can cause a 20-point rise in systolic blood pressure; drink alcohol in moderation; watch your salt as too much sodium and too little potassium can boost blood pressure; get at least six hours a night; reduce stress as both mental and emotional stress can raise blood pressure but meditation and deep breathing can lower it; and keep taking your medications that will stave off strokes and heart attacks.

Dr. Haiou Yang's research is published in the Journal of the American Heart Association, online August 28, 2006.

The Harvard Heart Letter is available from Harvard Health Publications.