Chemical Romance: How Hormones Influence Sex, Love and Relationships

If legends of love potions and love antidotes tell us anything, it’s that ever since humans figured out they could love, they knew that love is a thing that comes from the body.

In fact, much science has been done and much ink has been spilled over how human hormones regulate lust, attraction and long-term bonding. The conclusion? We have a lot less control over who we’re attracted to and who we fall in love with than we think.

Well, that explains a lot.

Here’s how the many chemicals flooding our system influence who we choose and how we feel.

Step One: Desire

You’re single. You’re horny. You go out to a bar and see an attractive person laughing with friends. You instantly imagine yourself kissing, touching and having sex with that person. This is the first stage of love: desire and lust.

This stage is controlled by two hormones: testosterone and estrogen (women have testosterone too, albeit in smaller amounts than men). These hormones regulate the reproductive system and activate when you find someone attractive. (This is why birth control pills can affect your sex drive. Learn more here.)

In other words, your body’s first reaction to a potential partner is, "Let’s make babies!"

Step Two: Attraction

This is where love gets more complex than a simple drive to get it on. A cocktail of powerful hormones (dopamine, adrenaline and serotonin) turn us into love-struck zombies. People under the spell of these hormones spend their time thinking about the other person, eat less and even sleep less.

Dopamine works to control our reward and pleasure centers. Dopamine gets activated when something good happens, something that produces a pleasurable reward. The high dopamine levels in the brain during this phase of love tell us that being around our partner is synonymous with pleasure. It's powerful stuff: The release of this hormone in the brain of new lovers has been compared to taking cocaine!

Adrenaline is also present in this phase. This is the hormone that makes your heart race, your body sweat and your mouth dry up when you go on that second date.

Finally, serotonin is another brain chemical related to all sorts of systems in our bodies, including appetite, mood and our understanding of social situations. When in love, serotonin makes us adopt obsessive-compulsive behavior; this is why we can’t think of anything but a new partner.

A recent discovery by Italian scientists added the increased presence of nerve growth factor in people in the attraction phase. This protein is related to the growth, maintenance and survival of neurons. Basically, during the attraction phase, your brain becomes more active. Scientists do not quite understand what this means for human sexuality and reproduction, but it’s an interesting new path to pursue.