MDMA (Ecstasy/Molly)

MDMA exerts its primary effects in the brain on neurons that use the chemicals serotonin, dopamine and norepinephrine to communicate with other neurons.
Serotonin is most likely responsible for the feelings of empathy, elevated mood, and emotional closeness experienced with this drug. Overall, these neurotransmitter systems play an important role in regulating:
mood
energy/activity and the reward system
appetite
aggression
sexual activity
sleep
sensitivity to pain
heart rate, blood pressure.