A study of 303 people in the U.S. compared the blood pressure of happily-married people, unhappily-married people and single people. The participants in the study were given portable blood-pressure monitors to wear for 24 hours. The monitors recorded blood pressure at random intervals throughout the day - even while participants were asleep. Each participant's blood pressure was recorded about 72 times. All participants drew up a list of friends in their social network and answered questions about the quality of those relationships. Married participants also completed questionnaires on the quality of the relationship with their spouses. Blood pressure at night - a risk factor for cardiovascular problems - was much lower in married people, particularly happily-married people, than in single people although overall unhappily married people had higher blood pressure than either single or happily-married people. Men and women in happy marriages scored four points lower on 24-hour blood pressure than single people and even having a supportive network of friends did not translate into improved blood pressure for single of unhappily-married people.
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