When someone we're attracted to steps into our life, three chemicals are let loose in our bodies:  phenylethylamine (PEA), which speeds up the communication between nerve cells and triggers the release of dopamine; dopamine, which gives us the feeling of bliss; and norepinepherine, which stimulates adrenaline production. The combined effect of these three wizards is something similar to amphetamines--amazingly high energy levels, euphoria, a racing heart, sweaty palms, and the shakes. Sound familiar? Well, the next time you talk to your new sweetheart on the phone for 5 hours straight or go on one of those marathon dates where you spend an entire day together and are still ready for more, you'll know who to thank.

The effect of these thrilling infatuation chemicals usually lasts anywhere from 6 months to 3 years (when our bodies build up a tolerance), and after that comes the true relationship test: Is there real love and friendship in the air? Many people don't stick around to find out--once the infatuation high is gone, they're out the door chasing around for a brand new love and more of the addictive amphetamine-esque bliss.

Sex, cuddling and tranquilizers

Another love magician that works on our bodies is oxytocin--a pituitary hormone composed of nine amino acids that is responsible for turning us on sexually and making us want to bond and cuddle. The bliss drug dopamine triggers its release into our system whenever we experience one of those ever-so-sexy cues--an intense gaze, a seductive touch, a luscious scent, the passionate tone of someone's voice, a steamy fantasy, or even a glance at someone's adorable smile (or whatever).

Touch seems to be the prime oxytocin stimulant--the more we touch, the more oxytocin is released, the more we're aroused. Both women's and men's breasts are particularly oxytocin-friendly, and people often enjoy discovering their partners' other oxytocin-stimulating zones, like ear-lobes, neck, and lips.

Working together with testosterone and estrogen, oxytocin brings about erection in men and uterine contractions in women, resulting in orgasm if there's a deluge of the drug. It's thanks to the excess of this spellbinding little chemical that women can experience full-body or multiple orgasms.

The flood of oxytocin at orgasm acts as a natural tranquilizer (lowering blood pressure and blunting sensitivity to pain and stress) and makes us want to cuddle and sleep. Generally, women are much more strongly influenced by oxytocin than men, hence the greater likelihood of women to become attached after a night of casual sex. Oxytocin also plays other significant roles for women--it's responsible for uterine contractions during childbirth and stimulates the release of milk during breast-feeding. The tranquilizing effect of oxytocin at these moments helps create the nurturing and bonding feelings a mother has for her child.

The real deal and morphine

After the initial high of infatuation wears off, a relationship usually only continues if there is enough real love to keep it together. The good news is that all the necessary ingredients for real love--like warmth, trust, friendship, compassion, a sharing of similar interests and lifestyles, humor, stability, acceptance and affection--are triggers for endorphins, the true-love drug.

Endorphins are natural opiates that act like morphine or heroin, allowing an increase in the flow of dopamine. They replace pain with pleasure, reduce stress and allow us to feel calm, relaxed, comforted, reassured and happy. As scientists have found to be true with other mammals, it's likely that friends and lovers get a surge of endorphins when they're together. And the longer two people are together, the stronger the endorphins become, creating a steadier more addictive effect than the infatuation amphetamines. On the flip side, when couples break up or are away from each other, they miss that loving endorphin feeling and experience what we call separation anxiety, which is probably caused by an actual endorphin withdrawal.

The overall effect? Endorphins act on relationships like feel-good glue, and the longer people are together, the more likely they are to stay that way.

The benefit of being a junky: Love drugs keep us healthy

Studies have found that being in a long-term loving relationship, or even feeling love for family, friends or pets for that matter, can improve our health. It's all thanks to the true-love endorphins, which, in addition to giving us a comforting, euphoric feeling, activate Natural Killer cells that boost our immune system to fight everything from the common cold to cancer. Endorphins also help to improve other physiological functions such as circulation and digestion. In addition, studies indicate that people who are in happy, loving relationships show lower heart risk factors, like cholesterol and blood pressure levels.  They also tend to live longer, healthier lives overall.

Where can I score some of those mysterious hots?
Just who will set these love chemicals loose in our bodies is anybody's guess. Someone can be exactly your type on paper, but when you meet in person, there's absolutely no chemistry (literally), and vice-versa. Although there are various theories about what the spell of love is actually made of, nothing has been scientifically proven. Here are a few of the possibilities:

* Pheromones, the perfect aroma
Scientific research is leaning towards pheromones as the likely messengers of love. Pheromones are hormones that we emit from pores all over our body (especially armpits, genitals, and sweat glands), which other people pick up with their noses. It's already been proven that in animals the scent of pheromones leads to sexual attraction and other behaviors, but the jury is still out as to whether or not the same holds true for us complicated humans.

We do know that, just like fingerprints, everyone's pheromones or "smellprints" are different. So, if this theory is correct, it means that we are looking for someone to send us a secret scented message, with just the right code, that will hit a small receptor in our nose that turns around and sends the signal to our brain for decoding. If it's a love-match, all the happy drugs start to flow.

* Looking for reproductive benefits
Another more Darwinian approach is that we're attracted to and fall in love with certain people for reproductive benefits. In other words, our love chemicals are triggered by people who look like they would be good to have babies and nurture a family with.

Studies have shown that what people hold as beautiful is the same across cultures, implying that who we want to partner-up with is part of our primitive physiological make-up, not just who stars in Baywatch.

Supposedly, men are naturally attracted to women who appear to be fertile and have high estrogen levels--women with small noses and jaws, full lips, wide-set large eyes, large breasts, soft skin and curvaceous hips and thighs (which show that they have enough calories stored to sustain pregnancy). Tell that to any girlfriends who think they have to be model-thin to attract a man!

Women are apparently naturally attracted to strong men who show signs of being good protectors and providers and who appear to have high testosterone levels--men with large jaws, deep voices, assertive personalities, and angular, T-shaped, muscular bodies.

* Good vibrations
Yet another theory is that our love chemicals are triggered by people who vibrate at the same speed as we do. Huh?! This metaphysical approach implies that our non-physical core energy (something like our souls) has a particular vibrational level. When we meet someone who is at the same level, our vibrations fall in sync, eliciting the feelings of attraction. Bring on the good vibes man!

* Working out issues
One psychological approach (among many) is that we get a gush of love--drugs when we meet people who remind us of a parent or someone from the past with whom we have certain issues or dynamics to work out. Familiarity is the initial draw, and then, as we work through the issue with our new partner, we continue to feel the love-drug high. This is fortunate, because if we weren't feeling the high, we might be running for the hills.

* Karma
Think out of the box for this one! Some people take love to another dimension, theorizing that we are attracted to people that we know from a previous life--people with whom we may have a karmic debt to work out or who can help us learn a particular lesson so that we can evolve to another spiritual plane. Ohmmmm