Courtesy David Ball The effect of Cupid's chemicals on my body some 40 years ago are unforgettable. I had so much energy I thought I would burst. I did about 50 pushups trying to relieve the pressure. I couldn't sleep. My pits were secreting overtime. Can you remember the feelings your first love (crush) produced?
dopamine (is) associated with states of euphoria, craving and addiction. High levels of dopamine are also associated with norepinephrine, which heightens attention, short-term memory, hyperactivity, sleeplessness and goal-oriented behavior. In other words, couples in this stage of love focus intently on the relationship and often on little else. How Stuff Works
"Oxytocin is released during child birth and also helps the breast express milk. Oxytocin is also released by both sexes during orgasm and it is thought that it promotes bonding when adults are intimate." oxytocin.org.
Endorphins, released during physical contact or sex, produce a general sense of well-being, including feeling soothed, peaceful and secure. Vasopressin and oxytocin, also released during sex, are believed to interfere with the dopamine and norepinephrine pathways, which might explain why passionate love fades as attachment grows.
Scientists are discovering that the same chemical process that takes place with addiction takes place when we fall in love. Brain scans of those love crazed individuals in the experiment above showed activity in the same brain area as those using cocaine or nicotine. Similar to other addictive chemicals, the chemical effects of passionate love lose their strength over time, too. After two or three years the chemicals responsible for "that lovin' feeling" (adrenaline, dopamine, norepinephrine, phenylethylamine, etc.) dwindle. Hopefully by then oxytocin, vasopressin, and endorphins resulting from physical intimacy are sufficient to keep the relationship going.
Here is a link to more articles about how love works.