Working for long hours could raise the risk of developing a hidden type of high blood pressure, that often goes unnoticed in regular BP check-ups, reveals a new study by the Laval University in Canada. Researchers looked at the health of 3,500 office workers and found that those who work long hours, more than 40 hours a week, were 66% more susceptible to have sustained hypertension and 70% more likely to develop masked hypertension. Published in the journal Hypertension, the study revealed that stress and lack of exercise could be few causes of high BP.