Above: Image © Pedro Simões, Wikimedia

This article was originally published on January 23, 2012 and reviewed and updated by the CurioCity team in September 2017.

A sure sign you have a crush on someone is that you think (and dream) about them 24/7. If it's somebody from your school, you might turn shy and blush when they pass you in the hall. If it's a celebrity, your room may be plastered with their pictures and posters.

Usually, these kind of crushes are based on physical appearance. Having a crush on someone is not the same as being in love, since the person you have a crush on is usually someone you have never met or hardly even know. Crushes often pass with time, but they can (and do) evolve into love!

The Chemistry of Love

There are three stages of falling in love. Each stage involves different chemical triggers.

Did You Know? The experience of falling in love is more intense for teenagers than it is for adults.

Stage 1: Lust

Lust, or sexual desire, is driven by the sex hormones testosterone and estrogen. These hormones become active by the time you reach your teens, a time in your life when you first experience the urge to love someone romantically.

Stage 2: Attraction

This is the "I have such a crush on (insert person's name here)" stage.

The reason the attraction is so strong (or addictive) is because the brain is stimulated to release dopamine, the neurotransmitter that activates your brain’s reward and pleasure centre.

Did You Know? Adolescent males are attracted to same-age or younger partners, while females prefer somewhat older partners.

An increase in dopamine can cause levels of serotonin, the neurochemical affecting your mood and behaviour, to become suppressed. This also happens to people with obsessive-compulsive disorders, which may help explain why you constantly think about your crush.

Stage 3: Attachment

The final stage of falling in love is when you decide to make a commitment to someone... that is, you decide to do the “boyfriend” or “girlfriend” thing. There are two "cuddle hormones" involved at this stage. Both are produced in the hypothalamus, the part of your brain that controls communication between the nervous system and the hormone-secreting glands. Specifically, social bonding with a mate is influenced by oxytocin and vasopressin by it’s release and interaction with the pleasure center in the brain.

Did You Know? One survey has shown that at age 15, dating relationships last an average of only 2-3 months.

So that is a general explanation of how people fall in love. But why are we attracted to someone in the first place?

Well, one way is through the scent that we give off - more specifically, through the release of pheromones. The other is based on appearance.

Appearance and Attraction

Attraction can be one of two types. There's the purely physical attraction: “Wow, they are beautiful”. Then there's the "I sure would like to go out with them" kind that has the potential to lead to romantic love.

Researchers studying the science of attraction believe that humans are wired to seek partners with the most perfect genes. The way we do this is by looking at the symmetry of another person's body. Researchers believe that, subconsciously, we are judging their fitness as a way of identifying potential genetic problems.

In closing...

Most adolescent crushes are innocent and are a normal part of a teenager’s experience in developing relationships with others, either as friends or as more. However, on some occasions, crushes can become obsessive to the point that a person entirely loses touch with reality. If you feel like you have an “unhealthy” crush, or that someone has an “unhealthy” crush on you, speak to a guidance counsellor or another trusted adult.

Learn more!

The Science of Love (2014)
BBC Science: Human Body

The Rules of Attraction in the Game of Love (2006)
Live Science

The science of love (2013)


Testosterone: primarily a male hormone, but females also produce it. It is responsible for male reproduction.

Estrogen: primarily a female hormone, but males also produce it. It is mainly responsible for female reproduction.

Dopamine: a neurotransmitter that makes you feel good as it activates your brain’s reward and pleasure centre.

Serotonin: a neurotransmitter that helps regulate mood, anxiety and happiness.

Hypothalamus: a part of the brain that is responsible for your motivation behaviour - for example, realizing you are hungry or thirsty.

Pheromones: a chemical substance that animals produce that affects the behaviour of other animals.

Stan Megraw

Stan is a writer/researcher, a PhD graduate of McGill University and was a member of the CurioCity team for several years. As a kid he dreamed of playing hockey in the NHL then becoming an astronaut with NASA. Instead, he ended up as an environmental research scientist. In his spare time Stan enjoys working on DIY projects, cooking and exploring his Irish roots.

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Avatar  Stephanie

But, what do i do if i just can't stop thinking about this guy?? Ughh, it's so frustrating. Nvm. 😅😫