Recent studies in neuroscience say that as people fall in love , the brain releases chemicals , including dopamine . Recent studies in neuroscience have indicated that as people fall in love , the brain consistently releases a certain set of chemicals , including pheromones , dopamine , norepinephrine , and serotonin , which act in a manner similar to amphetamines , stimulating the brain 's pleasure center and leading to side effects such as increased heart rate , loss of appetite and sleep , and an intense feeling of excitement .