Put your favorite song on.

Go on. I can wait. Open your iTunes or equivalent and pull up the playlist that brightens your whole demeanor the moment you see it. What’s on it? Bach? Stevie Wonder? Cole Porter? Katy Perry? Whatever your choice, it’s commonly understood that a tune can change our mood more quickly than a shot of tequila or the clouds covering the sun. The music we love can make us feel lighter, happier, more energetic, more motivated, distanced from the drudgery of the day. It’s feels a little like the giddiness of love.

Actually, it’s a lot like the giddiness of love.

Researchers at Montreal’s McGill University found that music stimulates the release of dopamine and can cause “euphoria and craving” and the dopamine-producing areas of the brains were the ones that lit up when people undergoing brain scans saw photos of their beloved, chronicled in the now-famous work of Dr. Helen Fisher and her team in “Why We Love: The Nature and Chemistry of Romantic Love.”

So love and music involve high levels of the same chemical, making it no surprise that we go into a bit of an altered state when we hear certain tunes, say “I’ve Got You Under My Skin.” What a prescient lyric that turned out to be, huh? The people we crave are under our skin, literally in our chemistry, the drips and drops of hormone and neurotransmitter that give us the warm fuzzies or emotional hunger pangs we get just thinking about that one special face.

That doesn’t mean we get to blame our behavior on this drug we involuntarily take (damn!) but it helps to know when you’re in deep that you’re not just a mad, flawed sap with no more self control than a hungry honey-badger. It’s just part of how love works.

In my book Crazy Little Thing: Why Love and Sex Drive Us Mad (which everyone needs a copy of right away!), I interviewed people who had experienced its extremes. We’re talking clinical depression, attraction to family members, committing murder and – probably the most shocking – one person who lived happily ever after. I also looked at some of the psychology and chemistry of love, and it’s that chemistry I want to focus on today – on Valentine’s Day; especially dopamine.

There are a number of chemicals involved in lasting love, like oxytocin and serotonin (bonding and feel-good hormones), but dopamine, part of our brain’s reward system, is what gives us that excitable infatuation. It’s craving, pleasure, sex, motivation, novelty and creativity. And as it increases so does testosterone, says Psychology Today’s Michael Castleman, so your sex drive soars in those initial stages. Awesome, right? Throw in some norepinephrine similar to adrenaline, and you have a racing heart, sweaty palms and sleeplessness. Creativity, novelty, sex, no sleep … sounds like the first week of liberal arts college! Spiffy!

Which brings us to the problem with this awesome sounding mix.

“We’ve found that when you’re rejected in love, parts of the brain associated with profound cocaine addiction are activated,” Dr. Fisher said about a 2010 study, which makes it understandable that it’s so hard to let go.

“When a reward is delayed in coming, reward-expecting neurons in the reward system prolong their activity,” she wrote in that study (I interviewed her in “Crazy Little Thing,” FYI), so just when those expectations should drop they increase. That means the reason you can’t get someone out of your head is not because your skull is so thick. It’s because it’s hard. The way I see it, it’s the difference between someone who is motivated to get a job and someone who is motivated to keep a job. The hunger of someone with something to gain is no match for the hunger of someone with something to lose.

The good news is that you can, given some time, come to your own rescue. You have an entirely highly evolved layer of brain called the neocortex, which means “new brain,” which means our human brain, which houses the ability to reason, feel empathy and control our impulses. By reasoning out, for example, the consequences of wallowing in self-pity over a break up we can start motivating ourselves to get past it – even if we’re not entirely over it. Once we start controlling our impulse to look back on the past we’re much more likely to see the future when it hits on us at a cocktail party.

And then you can start this exhausting, miraculous BS all over again.

Chemistry, though, is just a few layers of love’s complicated process. Our upbringing, psychology, physiology and cultural models all effect how we love.

What does it matter? Does it serve a purpose to know what chemicals are zipping through us when we fall hopelessly in love? I think seeing love as chemistry does help – especially when love hurts – because it takes something highly personal and allows you to see it as biological, even if just a little bit.

Women think nothing of citing PMS when they’re irritable. Yes, a woman momentarily bitches, but that doesn't make her a bitch. It’s a mutable state, not a character flaw. Trouble in love makes it so easy to see ourselves as weak or stupid when we can’t let go or have fallen for the human equivalent of the green potato chip … again. Seeing it as chemistry makes us able to recognize that it’s a mutable state. It is affecting us but it can and will change. And, as with PMS, recognizing it’s chemical nature can help us handle it more effectively.

Proof of nature’s randomness is that if who we fell in love with was a conscious choice there would be almost no pop songs. We’d all be too calm and happy for all that warbling about painful loss, romantic regret or being unable to let go. But we all get it.

Why?

Because it’s under our skin.

Consult your play list.