NEW YORK: More number of hours at work can lead to higher levels of blood pressure even after considering biological risk factors like gender and ethnicity, according to a study by medical scientists at the University of California, Irvine.
Dr Haiou Yang, Dr Dean Baker and their colleagues analyzed data from a 2001 California health interview survey covering some 24,000 people working in California and found that compared with people who work 11 to 39 hours a week, those who work 40 hours are 14 per cent more likely to have high blood pressure. Those who work 41 to 50 hours a week are 17 per cent more likely to have high blood pressure and those who work 51 or more hours are 29 per cent more likely to have higher blood pressure.
"We know that males, for example, or African Americans, are more likely to have hypertension. But once we controlled for that, what we found was that the number of hours people worked per week was still independently and significantly associated with higher rates of hypertension," said Baker, senior author of the study and director of University of California's Irvine's Center for Global Occupational and Environmental Health.
The scientists said about a third of people who suffer from high blood pressure do not know about it. So, there are chances that the study underestimated the real risk of longer working hours.
In Japan, there is a term known as "karoshi", which means sudden death from overwork. The team says "karoshi" can be caused by high levels of blood pressure.
The researchers noted that there are several factors that contributed to a person's blood pressure, which included the job type. For example, clerical work was found to have a 23 per cent higher risk of high blood pressure than a professional's work. But, the link between hours worked and high blood pressure remained, they said.
The study does not say that working long hours actually caused high blood pressure. It surmises that other factors like shorter recovery time and less sleep, more drinking, smoking and fast food and little time for exercises may be the cause. Besides, there is the question of "noxious psychological factors" like a feeling that one is underpaid for the job, which could lead to elevation of the blood pressure.
People should inform their doctors about the nature of their work and the time they usually spend on the work, say the researchers, and there is need for counselling in extreme cases.
Details of the findings are appearing in the October edition of the journal Hypertension: Journal of the American Heart Association.
