Source: shutterstock

I get so breathless, when you call my name I've often wondered, do you feel the same There's a chemistry, energy, a synchronicity When we're all alone —Corinne Bailey Rae

Falling in love can hit you hard—in mind and body. You feel irresistibly attracted to your crush. If things continue, you may feel a rush of euphoria, a longing to be together, passion, and excitement. You feel like you've found the most special, unique person in the world.

Fast forward a few years, and the excitement has likely gone down (except for a few lucky couples). But though the novelty may wear off, if all goes well, it has been replaced by a warm, comforting, nurturing type of feeling. You feel bonded in body, mind, and spirit. You share your hopes and dreams and work hard together to make them come true.

Each stage in this cycle can actually be explained by your brain chemistry—the neurotransmitters that get you revved up and the that carry the feeling throughout your body.

According to anthropology professor Helen Fisher, there are three stages of falling in love. In each stage, a different set of brain chemicals run the show. These stages are lust, , and love. I will discuss each below.

1. Lust

When you’re in the stage of lust, you feel physically attracted and drawn to to the object of your affection. You want to seduce them (or be seduced). There may be an element of mystery or an intensity that makes things exciting—imagine a hot one night stand.

Lust is driven primarily by the hormones in men and in women. Lust occurs across species and may be part of the basic drive to find a partner to spread our with. But lust is different than love. Injecting men with testosterone makes them desire a potential lover more, but not necessarily fall in love in any lasting way.

2. Attraction

In the second stage, you begin to obsess about your lover and crave his presence. Your heart races and you don’t feel like or eating. You may even get sweaty palms. You feel a surge of extra energy and excitement as you about the things you’ll do together. These feelings are created by three chemicals: norepinephrine, , and serotonin.

Dopamine: Increased dopamine is associated with , reward, and goal-directed behavior—hence the drive to pursue your loved one or create them in fantasy if you can’t be with them. Dopamine also creates a sense of novelty. Your loved one seems exciting, special and unique to you; you want to tell the world about his special qualities.

Increased dopamine is associated with , reward, and goal-directed behavior—hence the drive to pursue your loved one or create them in fantasy if you can’t be with them. Dopamine also creates a sense of novelty. Your loved one seems exciting, special and unique to you; you want to tell the world about his special qualities. Norepinephrine: Norepinephrine is responsible for the extra surge of energy and "racing heart" that you feel, as well as the loss of, in some cases, both your and your desire for sleep. It puts your body into a more alert state in which you are ready for action.

Norepinephrine is responsible for the extra surge of energy and "racing heart" that you feel, as well as the loss of, in some cases, both your and your desire for sleep. It puts your body into a more alert state in which you are ready for action. Serotonin: Scientists think serotonin probably decreases at this stage, but more studies need to be done. Low levels of serotonin are found in ( ) and are thought to cause obsessive thinking. In one Italian study of 60 students, those who were recently in love and those with OCD both had less serotonin transporter protein in their blood than regular (not recently in love) students.

3. Attachment

involves wanting to make a more lasting commitment to your loved one. This is the point at which you may move in together, get married, and/or have children. After about four years in a relationship, dopamine decreases and attraction goes down. If things are going well, it gets replaced by the hormones and vasopressin, which create the desire to bond, affiliate with, and nurture your partner. You want to cuddle and be close and share your deepest secrets with him or her. You plan and dream together.

Oxytocin: Oxytocin is a hormone released during (as well as during childbirth and breast-feeding). This may be the reason why is thought to bring couples closer together and be the “glue” that binds the relationship. There is a dark side to oxytocin as well. It seems to play a role in needy, clinging behaviors and .

Oxytocin is a hormone released during (as well as during childbirth and breast-feeding). This may be the reason why is thought to bring couples closer together and be the “glue” that binds the relationship. There is a dark side to oxytocin as well. It seems to play a role in needy, clinging behaviors and . Vasopressin: Scientists learned about the role of vasopressin in attachment by studying the prairie vole, a small creature that forms monogamous bonds like humans do. When male prairie voles were given a drug that suppresses vasopressin, they began neglecting their partners and not fighting off other male voles who wanted to mate with her.

What Can We Do?

Understanding the science of lust, attraction, and attachment can help you develop more realistic expectations of your relationships. Below are some tools to guide you through the stages of love:

Don’t mistake lust for love. Give a new relationship time before you start of a future together. Keep the dopamine flowing in a long-term relationship. You can do this by having date nights, taking lessons, or going on trips in which you do novel and exciting things together. Perhaps you go hiking in Costa Rica, climb a rock climbing wall, or go and see a thrilling movie. Keep the oxytocin flowing with sex and . Write cards and notes, hug and kiss, think of your partner when she's not around, share your hopes and dreams, and support those of your partner. Maintain some independence. If you’re the jealous, controlling type, start developing your own activities and friendships that make you feel important and cared about.

Follow Dr. Greenberg on Twitter