Blood Levels of Serotonin Are Differentially Affected by Romantic Love in Men and Women

People who are in love think about their beloved the whole day, which is supposed to be associated with serotonin. The research questions were how peripheral serotonin levels differ between individuals that are in love compared to individuals that are not in love, and how these levels are associated with obsessive thinking about the beloved. Because gender differences exist in romantic love and in the serotonergic system, gender differences were tested. Twenty participants who were in love (10 men) and 20 who were not in love (10 men) completed several questionnaires, and plasma and serum serotonin levels were assessed. The men who were in love had lower serotonin levels than the men who were not in love, while women showed the opposite pattern. The participants that were in love reported obsessive thinking about their beloved for 65% of their waking hours. In women, obsessive thinking about the beloved was associated with an increased serotonin level in serum. The serotonergic system seems to play a role in romantic love, but the effects appear opposite for men and women.