We all know the least-liked day of the week is Monday. It turns out the scariest day of the week is also Monday. Why? Our blood pressure soars on Mondays. The stress of returning to work on Monday morning can trigger a dangerous increase in blood pressure, according to a recent study from Tokyo Women's Medical University. This may explain why there are more deaths from heart attacks and strokes on Monday morning than any other time of the week. "If somebody already has cardiovascular disease, then it might just tip them over the edge and trigger a heart attack," Keith Fox of the cardiovascular research unit said. There are 20 percent more heart attacks on Mondays than on any other day. High blood pressure is a major risk factor for heart disease, and the higher it climbs, the greater the force exerted by blood on the walls of the arteries every time the heart beats. Among those who went to work on Monday morning, there was a surge of blood pressure as they got ready for work. Those who could sleep in and not work on Monday did not experience the same increase, which suggests work-related stress is to blame for the increased blood pressure.