Science on Valentine’s Day

Science of LovePeople don’t usually associate science or other STEM fields with Valentine’s Day or really with romance in general. That’s fairly reasonable because they aren’t generally very connected. But there are nerds out there who are interested in the brain chemistry of people in love and other sciency aspects of this date.

So in preparation for this Thursday, read on about the chemistry of being in love, along with some other cool science.


Brain Biochemistry

Love is split into three different stages:

The first could be called the “love at first sight” stage. In both men and women, testosterone and oestrogen are released when meeting a potential partner. This same stage is found in many animals as simply an instinct and reaction based on the need to mate and reproduce in the natural environment. However as humans, this stage is normally when you just meet someone and decide to start up a conversation.


Stage two is more serious- attraction. This is the more typical feeling of being ‘in love’. At this point two chemicals that you might have heard of before are released: noradrenaline, dopamine and one other chemical, serotonin, is suppressed.


This is one of your fight-or-flight hormone (similar to adrenaline). So how is that connected to love? Well, your body actually instigates a stress response when you’re around a person you like and starts the breathlessness, racing heart rate and other lovely symptoms.


Dopamine is one of your “happy chemicals” that your brain uses a reward system. This means that it is released when you do things that feel good and it makes you feel even more energetic and excited. However, you can end up “addicted” to dopamine release and cause a more severe reaction when you are separated from your partner, either in the short term or long term.


It is suggested that serotonin is suppressed by the increase in testosterone from stage 1 of love (above). What this means for you is that your brain starts to obsessively and intrusively think of your significant other. This same response is seen in people with OCD (Obsessive Compulsive Disorder) and their hyper-fixation on particular thing.

Together, the changes in these three chemicals mean that you physically feel different (breathlessness, racing heart, sweating, etc…), emotionally feel amazing because your brain’s rewarding you and you stop thinking about most of the other important things that you probably should think about.


Stage 3 is attachment and is naturally the furthest along. Once a couple have spent time together and travelled through stages 1 and 2, they move on to needing bonding time to complete this final stage of love. At this point, two final hormones are released: oxytocin and vasopressin. Oxytocin is involved in both romantic couple bonding but also in bonding with children during breastfeeding and other activities. It also helps heighten your ability to understand and respond to your partner’s social cues and behaviour which should help you to get along even better. Vasopressin has similar affects within a relationship, however, it acts more significantly in men, while oxytocin has a greater role in women.

And best of all in this last stage is that your serotonin levels actually return to more normal levels. The infatuation wears off which is a good thing for you in the long run (because remember, it’s the same hormone that is involved in OCD and certain other mental illnesses). Your body also stops the stress response that initial instigated release of noradrenaline and cortisol as your relationship is no longer stressful to you, and that’s also a good thing for you! The dopamine release continues to reward your brain and make you feel happy in your relationship.


Screen Shot 2019-02-11 at 8.33.46 pm
This awesome Valentine’s Day card! Image of card from Gaius J Augustus’s website, used with permission


So maybe you can impress that science nerd in your life with some of these cool facts. Or perhaps impress them with one of these nerdy-as and awesome science-themed Valentine’s Day cards from Gaius J Augustus’s website. This one featuring a serotonin molecule is my favourite!



Now that you’ve had your dose of science for the week, go enjoy Valentine’s Day, either with a partner, friends or by yourself with a cup of coffee!

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