How can love be a chemical reaction

The chemistry of love

Big feelings through small processes: does chemistry determine our emotional life?

"My heart is dancing and every molecule is moving," says a love song by the German band "Mia". Chemistry may even seem romantic to lovers! Maybe because we don't yet fully understand how and why we fall in love. As always in love, it is precisely the undiscovered, the invisible that attracts us.

Love, the bond between people, our social behavior as a whole are so complex that many generations of scientists will work on them. But we already know some things. Researchers have found out which areas of the brain and which hormones and neurotransmitters are activated in brains in love.

The stages of love

In order to look at love scientifically, we have to distinguish two phases:

  • the honeymoon phase
  • the attachment phase

You could also say: First you “fall in love”, later the infatuation can develop into a mature “love”. Different phenomena occur in the human brain during the two phases of love.

Love is addicting

Functional magnetic resonance imaging (fMRI) provides information about what our brain does when we are freshly in love. This allows a three-dimensional "video" of the brain to be recorded while a test person is thinking of something specific. When lovers look at the object of their desire, other areas of the brain are stimulated than when other strong feelings such as fear or anger are stimulated.

Young love is a unique feeling. Researchers say the brains of people who have just fallen in love can best be compared to those of cocaine users. Love is addicting. Everyone who knows the withdrawal symptoms that a lost love leaves behind knows this.

++ More on health trends: 7 reasons why we fall in love ++

The role of neurotransmitters in lovers' brain chemistry

This observation coincides with the findings of the biochemists who have researched the brain chemistry of lovers. The researchers found that the neutrotransmitter situation in brains newly in love is in a highly excited state.

Neurotransmitters are substances that help transmit nerve signals. They are given off by one nerve cell and absorbed by another; they can be thought of as chemical signals. Neurotransmitters such as dopamine, serotonin, norepinephrine and phenethylamine occur in different combinations and concentrations in different feelings or thought processes.

Although certain transmitters are associated with certain feelings - dopamine is considered to be a "messenger of happiness" - it is not possible to assign exactly one substance to every feeling. The human brain is much more complicated.

Effects of love on the body

Chemists found high doses of dopamine, norepinephrine and phenethylamine in the brains of lovers. These amphetamine-like transmitters put the body in a state of arousal and increase focus. The heart beats faster, blood pressure and body temperature rise, we concentrate entirely on our partner, the object of biochemical desire.

Phenethylamine, which is found in the brains of lovers, leads to a deficit in attention deficit and in excess to paranoia. If you're feeling neglected by someone new in love, don't hold it against them: their neuter transmitter situation is similar to that of a patient with OCD.

Young love is an obsession, with the help of brain chemistry it ensures that we literally cannot think of anything else. "I'm crazy about you" is a biochemically more precise description than one might assume at first glance.


When two such confused people meet, the tension inevitably discharges under the covers. After sex, the body releases a mixture of serotonin, vasopressin and endorphins, which are opiate-like messengers of happiness. This cocktail gives the body relaxation, satisfaction and - as studies suggest - a need for attachment.

Biochemists have turned their attention to the two peptide hormones vasopressin and oxytocin, which are produced in the brain. When they do, we are relaxed, satisfied, dopamine and norepinephrine levels are low. This is the opposite of being in love acute.

Could oxytocin and vasopressin herald the transition from being in love to being in love?

"Cuddle hormone" oxytocin

If the genes that are responsible for the production of the two messenger substances are switched off in animal experiments, they become completely socially incapable. They can no longer even tell their conspecifics apart, let alone enter into a social bond. How oxytocin and vasopressin work in the human brain is still largely unknown.

However, there is no doubt that it regulates interpersonal bonding. Oxytocin can be detected in the brains of breastfeeding mothers in similarly high doses as in couples who nestle against each other after satisfactory sexual intercourse.

No wonder that the messenger substance has been nicknamed "cuddle hormone" by the media. The American journalist Viola Gad carried out a self-experiment and ordered oxytocin in the form of a nasal spray on the Internet. The hormone preparation is offered in web shops as a remedy for stress and insomnia.

Before the third date with a man, she sprayed the hormone into her nose and published the results under the title "Can get a friend with oxytocin". The result was sobering. While Gad felt loose and relaxed after taking it, the relationship didn't work out.

Is the chemistry right?

It is good to know that there is no switch for love or a stable bond between two people that you can flip by taking a drug. No laboratory will be mixing the love juice from Shakespeare's Midsummer Night's Dream in the foreseeable future.

One thing is clear: as scientists, biochemists and neuroscientists can observe the mechanisms of love. However, how a couple falls in love, why it clicks between two people, why the chemistry is just right, chemistry doesn't know. Do chemicals force us to fall in love or are they just a mechanical physical reaction to the big feelings?

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Mag. (FH) Axel Beer
Editorial editing:
Philip Pfleger, Katrin Derler, BA

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