High blood pressure is known to reduce sensitivity to pain, but a new study shows that it may have a more general influence on emotional response by smoothing out emotional high and lows. Cynthia Pury, Ph.D., of Clemson University, and colleagues tested 65 volunteers, first recording their blood pressure and then showing them 32 photographs. Half the pictures were intended to elicit a positive emotional response and half a negative response. After viewing each photograph, participants rated their reactions on scales of happy to unhappy and calm to excited. The average age of participants was 20 years old. Their findings appear in the journal Psychosomatic Medicine. Systolic blood pressure (the "top" number in blood pressure readings) correlated with more neutral, less extreme responses to the photographs, she says. There was a similar but more modest effect for diastolic blood pressure. The responses were similar for both positive and negative emotional response, on both the happy-sad and the calm-excited scales. Increases in blood pressure, Pury and her colleagues speculate, may help people cope with intense psychological stimulation by limiting emotional reactions. This may raise the threshold for stress reactions. "If those with higher resting blood pressure perceive their environment as less threatening, they may stay in stressful situations for longer," she says. "Likewise they may seek out greater levels of excitement."