Reducing love to its molecules: It really comes down to chemistry, after all

Love at first sight kick-starts a chemical reaction in your body that can last a lifetime, it turns out.

"Love is no different than slamming a hammer on your tongue or eating spicy pizza," said Université Laval chemistry Prof. Normand Voyer.

"It's much more romantic, but love at first sight — just like love — is really, truly only chemistry."

Voyer said the brain produces a cocktail of chemicals that take over the body when someone experiences the feeling of love at first sight.

First, there is a rush of phenylethylamine, a naturally occurring amphetamine produced in the centre of the brain, which gives people an "immense feeling of comfort," Voyer said — what people think of as being on "cloud nine."

Next, there is dopamine, which has the opposite effect, jump-starting the nervous system so people feel over-excited. You've all met those people who've just fallen in love and just can't prevent themselves from smiling or laughing.

Third, there is norepinephrine, which causes a sense of euphoria.

"Love is associated with doing crazy things, saying crazy things," said Voyer. "That is the molecule responsible for you acting like a stupid person."

Finally, there is adrenaline, which increases the heart rate, body temperature and blood pressure — the reason someone who has just fallen in love appears flushed.

"Those are the ingredients of love at first sight," Voyer said.  

Putting love to the test

The chemist has also come up with a gadget to test the strength of a crush.

When the body produces adrenaline, body temperature increases, and the palms begin to sweat. Sweat is largely a mixture of water and sodium chloride and conducts electricity.

His machine measures the electrical current that passes between two people holding hands and the machine itself, which causes the machine to light up and make a sound proving irrefutably that the users are in love. (Of course, it could also just mean the hand-holders are nervous.)

Voyer said the findings aren't scientifically accurate, but the machine is still a fun little item.

"Love is a fantastic playground for learning new chemistry," Voyer said.

Normand Voyer/Facebook

Then there's oxytocin

About 18 months into a romantic relationship, the four initial chemicals produced when someone falls in love start to subside, replaced by a different molecule: oxytocin, which encourages long-lasting love.

Oxytocin is also produced during sexual intercourse and childbirth.

At a low dose, oxytocin can act as a muscle relaxant, making people feel calm and secure.

"Basically what you end up with is a feeling of comfort and well-being by being with someone, and love can last for years and years and years," Voyer said.

"After 50 years of something like that, people are so involved with each other that they become dependent," Voyer said. That can lead to anxiety when the couple has been separated.

Voyer said although scientists are clear on what happens chemically when people fall in love, it's far less clear why peoples' brains release love chemicals in response to some people and not others.

In other words, no one knows why people fall in love with the people they do, but Voyer said it's likely a combination of genetics and the subconscious.

"If I knew the answer, I would not tell everyone in the world," he said. "I would patent it and become rich."

Listen to CBC Breakaway's full interview with Prof. Normand Voyer, below: