Let’s Talk About Sex, Baby: Love and Lust.

Ah, February. Just hearing the name of this month makes me think of the color pink, boxes of chocolates, hearts and just romance in general. After all, February is the month of Valentine’s Day.

So, a while ago, I wrote about what happens inside your body (well, actually, your brain) when you have a crush, but what about when a person is in love? And honestly, what’s the difference between love, lust and a crush?

As always, we turn to PubMed.


First of all, let me just say, if you’re ever feeling bored – search for the term ‘lust’ in PubMed. The results are WILD.


I decided to try the term ‘sexual desire’, instead. After all, the Oxford definition of lust is “a very strong sexual desire”.

From what I understand, sexual arousal/desire involves psychological, physiological and even genetic components.

  • Genetics: genes play a role in determining who/what we’re attracted to. Basically, you and your great-grandma might have the same type. 

From what I understand, physiological responses and psychological responses are linked together. To make the explanation easier, let’s take an object of attraction, or a stimulus.

  • Physiology: In short, upon seeing/thinking about the stimulus (hence the psychology tie-in), various different physiological mechanisms kick in. You’ve got the pituitary-gonadal axis (releasing those testosterone/estrogen, etc. hormones), the neural pathways causing the sympathetic and parasympathetic reactions (fast heart beat, widened pupils, erections and secretions), spinal and cerebral circuits for response integration and control, and neurochemical transmitters and modulators[1]. Everything works together inside, to bring about the outside reactions. 

In men/people with penises, the ultimate response would result in an erection, while in women/people with vaginas, there would be vaginal lubrication and clitoral enlargements. (Which, I suppose, begs the question: what happens in trans people? Or people who have undergone orchidectomies, penectomies and hysterectomies? To be explored later…)

  • Psychology: Now, this is what’s difficult to encapsulate. Psychological factors can influence what we’re attracted to, when we feel attracted and even how we get attracted. 

Studies show that sexual desire can be reduced when stressed, depressed, tired or distracted. There are also studies that show that libido can be negatively affected by loud sounds and bright lights (hence, I guess, setting the mood). So, I think that answers the when and how aspects. As for the what, I think that ties up with genetics once again. 

TL;DR: Lust is a combination of a bunch of different things, but ultimately results in a more physical reaction. 

2. Love

So, what is love? (Alexa, play What is Love by Twice)

According to dear old Oxford: Love is an intense feeling of deep affection. 


According to Wikipedia:

Love encompasses a range of strong and positive emotional and mental states, from the most sublime virtue or good habit, the deepest interpersonal affection, to the simplest pleasure.

Um, okay. So, basically – love can be of different types, from “loving these french fries” to “loving your dog” to “loving this other human being”. But, of course, we’re talking about romantic love. 

There are way too many definitions for romantic love, so I think I’ll use a quote from Emma, by Jane Austen: 

“If I loved you less, I might be able to talk about more”

I feel like this quote makes sense and makes no sense at the same time, which I think is what love is. 


Physiologically, there are several hormones in play. Dopamine is released when we’re around someone we love, which leads to the release of nor-epinephrine, causing loss of appetite and a bit of insomnia (I guess this is where the term so in love I can’t eat or sleep is from). There is also reduced serotonin levels, which coincidentally, is also seen in people with OCD. Maybe this is why we can’t get someone off our mind when we’re in love[2]?

Dopamine, noradrenaline and serotonin… sounds familiar? This is the exact response that happens when we have a crush on someone. So, what differentiates a crush from love? 

In love, there is also the feeling of attachment, influenced by two more hormones – oxytocin and vasopressin. These two hormones, oxytocin especially, causes the feeling of “bonding” and reinforces positive feelings we have towards someone. 

In general, I believe that we get a crush on what we think someone is like. Whereas, we love someone for who they are. It’s a feeling of attraction but solidified by the bonding and comfort we have with someone. 


To sum it all up, lust results in a more physical reaction, whereas love would be more of a chemical reaction… two different reactions in two different heads, if you will (sorry, not sorry) 😉

Jokes aside, the amount of research on this subject is astonishing. To think that a few chemicals in our brain can cause so much havoc! I’ve seen research papers on lust and aggression, lust and murders, lust and diabetes (sildenafil/Viagra has an effect in diabetic patients apparently!). An interesting point to note: there is more research on sexual desire in men, than women.

From what I’ve read in romance books, love is more of an abstract concept, so attempting to encapsulate it in a scientific paper might be difficult. But, it makes for an interesting read.

In honor of Valentine’s Day, let me close with a quote from one of my FAVORITE books, Ever After Always, by Chloe Liese:

“Romance is about the centrality of loving relationships, and it reminds us that human connection is vital to existence, rather than glorifying egoism or violence or greed.”


  1. Motofei IG, Rowland DL. The physiological basis of human sexual arousal: neuroendocrine sexual asymmetry. International journal of andrology. 2005 Apr;28(2):78-87.
  2. Wu, K. Love, Actually: The science behind lust, attraction and companionship. SITN, Harvard.edu [Internet]. 2017 Feb 14. Available from: https://sitn.hms.harvard.edu/flash/2017/love-actually-science-behind-lust-attraction-companionship/#:~:text=High%20levels%20of%20dopamine%20and,eat%20and%20can’t%20sleep.

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