Updated: Jul 25, 2020

Have you ever come down with a case of love sickness? Symptoms may include a constant pining after somebody, a bout of unrequited love and complete and utter takeover of all your thoughts. From a young age, many of us get a ‘crush’ on somebody - and the word itself only half illustrates the intense burden this state of mind can bring. While childhood crushes may come and go each playtime, with age (and lotsa hormones thrown in) these overwhelming sensations become much more intense. You could develop a crush for someone you've known for a while, hardly know at all or have never even met (kissing a celebrity's photo any one?). And if your crush reciprocates your affections, a full-blown state of love blindness can kick in. This transforms your rational perception of the individual you are directing your emotions towards from a normal human into a god/dess-like being. So, it comes as no surprise that if things don’t work out for this romantic relationship, you can be left inconsolable with a lingering obsession for your perceived ‘true love’. And no matter how many times people tell you there are ‘plenty more fish in the sea’, you feel like you caught the most perfect fish but it jumped overboard and got lost at sea. So how does the brain get hooked on one person? And why is it so hard to let go?

It’s just a little crush: Developing a devotion

A crush can hit you out of nowhere. Maybe you only just realised that your friend's cousin has the most beautiful laugh you’ve ever heard, or a complete stranger who made eye contact with you across the office at your new job is going to be your forever love. All of a sudden, this person takes over your day and night dreams and when you are around them, you are overly aware of everything you say and do; making you act totes awks. But how can one person be the fixation of your desires when you have never noticed them in that way before or hardly know them at all?

In neuropsychological terms, a crush is believed to be a person whom you project your own desires onto. Of the little pieces of information you know about this person, you fill in the blanks with all the traits you want from a lover. And neurological sensations support these evidence-devoid judgments. Initial attraction to an individual, normally mediated by looks, scent, a personality trait or general charisma, causes an increased release of dopamine and norepinephrine, while decreasing levels of serotonin. Dopamine is released from the ventral tegmental area into the reward circuitry of the frontal and limbic ('emotional') brain areas, causing feelings of euphoria and giddiness when you are around your crush. Norepinephrine (aka noradrenaline) is synthesised from dopamine and is responsible for keeping the brain and body alert during stressful situations. In terms of your love interest, norepinephrine release leads to increased focus and arousal, as well as a pounding heart, sweaty palms, loss of appetite and sleepless nights. Finally, serotonin, a mood stabilising hormone, decreases in the brain during attraction which promotes obsessive thinking; letting your crush occupy the majority of your thoughts. Together, these chemical shifts create the butterflies in your stomach, overexcitement and constant fantasies when you are crushing hard.

I just can’t get you out of my head: Obsession

So, what happens if your crush from afar becomes an intimate partner? Once you start seeing someone, the same sensations you felt from your initial attractions become even more intense. Any barriers you had up about potential rejection have been dropped and are replaced with trusting feelings, meaning you can really start to let yourself think that this individual will become a permeant fixture of your life. Serotonin levels reduce in initial stages of romantic love to a similar level found in people with obsessive compulsive disorder (OCD). In individuals with OCD, blocking uptake of serotonin is a somewhat affective treatment; suggesting having high levels of serotonin outside neurons prevents OCD-like tendencies. Therefore, low serotonin in early stage romance could promote fixation with your new lover.

As well as chemical changes and activation of brain regions associated with reward, there are specific brain areas which are deactivated in early-stage romantic affairs. This deactivation affects areas such as the amygdala in the temporal lobe and parts of the prefrontal cortex. The amygdala is responsible for fearful emotions and memory, as well as being a key player in the ‘fight or flight’ response whereas the prefrontal cortex plays a pivotal role in judging and critical assessment. Deactivation of these areas associated with ‘negative’ thoughts and feelings is thought to prevent critical judgment of your lover; allowing you to focus on the good and ignore the bad. In addition, the network of brain regions in the frontal, parietal and temporal lobe associated with mentalising, which also allows you to dissociate ‘yourself’ from ‘others’, is also deactivated as love drives the unity of yourself with another. Therefore, your ability to rationalise is somewhat impaired when you are lovestruck, potentially leading you to make some out of character and senseless decisions.

After the love has gone: Rejection

Unfortunately, many crushes do not turn into budding romances. You finally pluck up the courage to ask out your love, but they are just not on the same page as you. Or after initiating a romance, the other person decides to call it quits. And while you try to take the rejection in your stride, internally you have a really tough time dealing with the fact the person who has consumed your thoughts is not going to be your 'one'. Trying to come to terms with this can make you feel down, act irrationally and constantly run over events to try to understand why it didn’t work. These symptoms are similar to those experienced during withdrawal from addictive substances and this is thought to be reflected in brain mechanisms.

A study examined individuals who had been rejected by a partner who they were still in love with using fMRI technology. When these individuals were shown images of their previous partner, activated brain regions included the ventral tegmental area, associated with reward, alongside other areas such as ventral striatum, cingulate gyrus, the insular cortex and the medial and lateral orbitofrontal and prefrontal cortices. The activation of dopaminergic reward centres in these individuals reflect they still feel deep love for those who have rejected them. Some of the other activated areas are similar to those with cocaine addictions associated with ‘craving’ behaviours, thought to be augmented by dopamine release in the striatum, and ‘high’, caused by cingulate stimulation. In addition, activation of the insular cortex reflects the ‘hurtful’ side of rejection as this area is associated with the sensation of physical pain. Together, the brain appears to go through withdrawal symptoms when experiencing rejection from a long-term love and most probably also from a crush or new love. Cerebral activity in rejection mimics that of substance addiction, making you crave your ex-lovers affections, and your brain makes you physically hurt. The concoction of such strong sensations is worthy of a rehab check-in with other addictions, explaining why it is so tough to get through a breakup and to let the idea of your 'perfect relationship' go.




In summary, love is a hard game in which your brain is the true MVP. You quite literally lose your mind over someone by up-regulating 'high' sensations and suppressing those negative feels, making a specific individual your complete focus and seem like the only one for you. If you are currently being crushed by a crush, the best thing to do is to try to take back control of your mind. You can do this by trying to remove this lucky person off the pedestal you have put them on by making them 'human.' If you hardly know this person, the 'perfectness' you are filling into the blanks is more than likely completely wrong. And besides, no one is perfect so it is highly unlikely a single person holds every trait you've ever wanted in a partner. Try to look at this person through someone else's eyes and spot all their really annoying characteristics. This is helpful for you to move forward and also, it is rather therapeutic. You can defeat you crush. After all, love is all in your head.

Materials used to scribe this love letter

Reasons for Crushes

Role of Serotonin in OCD

The neurobiology of love

This is your brain on love

Reward, Addiction, and Emotion Regulation Systems Associated With Rejection in Love

Updated: Jul 24, 2020

Attraction. Desire. Devotion. Dedication – just some of the vital characteristics needed to create a long-lasting love. However, unlike the ‘sugar, spice and everything nice’ ingredients required to create a girl (thanks for that super accurate recipe Powerpuff girls), aspects of loving feelings can be described by actual real-life chemicals. You constantly hear of two individuals having “good chemistry” when entering into a blossoming romance, but have you ever thought about what these chemicals are and how they act to induce a love-struck state? The chemicals underpinning love have the ability to make you weak at the knees, delusional and irrational, but also promote unwavering trust and commitment. Technically, a similar mix of emotions could be artificially induced by the administration of a concoction of ‘love chemicals’. Some companies have even developed a ‘liquid trust’ spray to blindside consumers into signing their money away and instil confidence in big business. But can something so deep and meaningful really be mimicked?

The neurological mechanisms which summate to L.O.V.E have been extensively studied in the monogamous mammal; the prairie vole. That’s right, there are cute lil voles out there who hold lil hands and have lil families and live happily ever after (like a real life Sylvanian family). The prairie vole forms a ‘pair bond’ with their partner and this normally lasts for life (actual relationship GOALS). Prairie voles with a pair bond will co-parent by raising their pups together and will rarely move on if their original partner dies. So legit, how do they have this dedication? What is their recipe to a long-lasting relationship?

Some of the chemicals found to be fundamental to prairie vole commitment are oxytocin, arginine vasopressin and dopamine. These neuropeptides are also found in humans and it is thought that their interactions with their neuronal receptors in specific brain regions and with each other augment that all-consuming love the great play-writes describe. So, in order to learn about why Romeo died for Juliet, let’s get down to how these particular love chemicals act in your brain.


Oxytocin is a neuropeptide produced in a brain region called the paraventricular hypothalamus, a region important for regulating autonomic functions, and it is released by the pituitary ‘master hormone’ gland. Oxytocin acts at oxytocin receptors (OTR) on neurons. In the praire voles, these receptors are found in high numbers in the caudate putamen, nucleus accumbens and prefrontal cortex; areas associated with the release of the ‘reward’ hormone dopamine (more below).

Oxytocin is implicated in both maternal and romantic love; being released during breast feeding to enhance the mother-infant bonding as well as during sexy time with a partner, especially in women. This is unsurprising as both parental and romantic relationships require the formation of a strong bond which enables you to take risks for the sake of your partner. In the prairie vole, infusion of oxytocin into the brain of a female prior to mating leads to quicker formation of the pair bond with their partner, suggesting this hormone plays a pretty important role in solidifying the long-term aspect of romantic relationships. If OTR’s are blocked in the prefrontal cortex and nucleus accumbens of female prairie voles, the pair bond cannot be made and oxytocin knock-out mice (containing no oxytocin) fail to recognise individuals they have previous met. This info suggests oxytocin's reaction with specific brain regions augment the development of a loving bond whereas the general action of the hormone across other brain regions is important for recognising the individual with whom you have made that bond. Because, let’s be honest, it would be pretty hard to identify your partner fo’ life if you couldn’t tell them apart from all the other ‘fish in the sea’.

Arginine Vasopressin

Arginine vasopressin (AVP) is another neuropeptide and hormone with peripheral effects such as reabsorption of water from tubular fluid and artery constriction. However, in the brain, this neuropeptide plays a role in pair bonding and ‘male’-aggressive behaviours. AVP acts on AVP receptors, V1aR, found in high levels in the ventral pallidum (part of the reward system), medial amydala (fear/fight or flight) and mediodorsal thalamus.

In those well studied, monogamous prairie voles, AVP is vital for pair bond formation in males. In fact, the role of this hormone is so strong that male prairies infused with AVP in the brain form a pair bond with females without mating. If the V1aR AVP receptors are blocked in the ventral pallidum only, the formation of a pair bond during mating is inhibited and when all V1aR receptors are blocked using a drug, male prairie voles cannot recognise their mates. So similar to oxytocin, specific brain regions mediate pair-bond formation in the male brain and this happens to be a region associated with reward. In humans, AVP levels are found to be elevated in men during arousal but it is unclear how these levels distinguish a life-long love from a one-night stand.


Dopamine is a neurotransmitter synthesised in neurons in the ventral tegmental area and substantia nigra. Dopamine is the major neurotransmitter which activates the ‘reward circuit’ in the frontal cortex and its release is associated with goal-directed behaviour, promoting learnt-motivation for certain actions by making you feel gooooode. Dopamine acts at D1 (signal promoting) and D2 (signal blocking) receptors, found in different populations of neurons in the prefrontal cortex. It is thought that activation of prefrontal D1 receptors leads to risky decision making whereas activation of D2 receptors in this region promotes more flexible thinking; considering the reward-risk benefits of an action.

During mating in prairie voles, dopamine systems are activated as these regions contain varying levels of OTR and V1aR, linking copulation and reward sensations. During mating, it has been reported these mammals experience a 51% increase in extracellular dopamine levels and if D2 receptors are activated by drugs, partner preferences are accelerated without the need for mating. In the male prairie vole, the levels of D1 receptors, mediating 'risky' decision making, are actually reduced in the two weeks following mating and pair bond formation; potentially preventing the formation of new pair bond. Even in non-monogamous mammals such as rats, individuals prefer to spend time with partners they have 'done the deed' with over new potential partners due to activation of D2 receptors in the nucleus accumbens when near their previous partner. In humans, fMRI studies on individuals looking at images of their partner vs other faces have revealed dopamine-rich regions are activated by their love interest only. It is thought dopamine acts in tandem with oxytocin or AVP to form a strong, rewarding bond with those you romantically love. In praire voles, bond formation requires D2 activation in the nucleus accumbens in both sexes with concurrent activation of OTR in the nucleus accumbens and prefronatal areas in females and V1aR in the ventral palladum in males. These signals occur alongside olfactory cortex (smell detection) activatino in order to link the hedonic properties of mating to one specific individual.

Can we make a fully-functioning love potion?

So, what would happen if you mixed oxytocin, AVP and dopamine and gave it to your love interest? Would they automatically fall head over heels for you? Well, like all neuroscience, it would most probably be a bit more complicated than that. All of these neuropeptides have receptors across many different brain regions and are responsible for different functions, not just playing cupid. It is also very likely that the timing of the release of these hormones in specific brain regions is vital for catching the love bug. For example, the hypothalamus is reportedly activated in sexual arousal and romantic love but not maternal love. And undoubtedly, there will be many other specific interactions and chemicals involved (I feel you, adrenaline). So much more research needs to be done on the human elements of love in many types of relationships (not just the love between men and women) for us to pin down a more solid mechanism for our monogamous desires. As for the potency of liquid trust? Well, while a squirt of oxytocin up your nose may dampen your suspicions of someone for a few hours, this will soon wear off and you will probably be super freaked out somebody has tried to chemically win you round. While it seems that we might understand some of the key ingredients for the most powerful love potion of all time, the secret recipe of how to mix these ingredients remains locked up inside your brain. And I don’t think it will be release on BBC good food anytime soon.




Happy Palentines everyone! All the info for this article was gathered from the following sources:

Love: Neuroscience reveals all.

The Neurobiology of Pair Bonding

The Neurobiology of Love

Prefrontal Dopamine D1 and D2 Receptors Regulate Dissociable Aspects of Decision Making via Distinct Ventral Striatal and Amygdalar Circuits

Updated: Jul 25, 2020

Ask most people to describe a healthy lifestyle and they will state similar actions: eat fruit and vegetables, drink plenty of water and exercise. Over the past few decades, the importance of exercise has been acknowledged by governments all over the world; with health campaigns actively encouraging individuals to walk 10,000 steps a day, get their heart rate up for 150 minutes a week and build muscle strength by weight training or carrying heavy shopping (1). Additionally, scientific and medical research on the health benefits of exercise all point towards the same conclusions – exercise increases longevity and reduces the occurrence of chronic illness. Maybe even more effective, many celebrities who influence masses of people on a daily basis are choosing the gym over gin. The ‘it’ girl of the noughties falling out of a club at 2am has been replaced with the ‘fit’ girl of 2019 up at 5am ready to workout. Thanks to social media, fit is the new fashion and many users find themselves skipping the late-night benders to gain themselves a gymshark-worthy physique. Exercise is on the up and the desire to become fit is stronger than ever before.

A combination of words you rarely hear paired together are ‘exercise’ and ‘unhealthy’. However, a mental health problem which is uncommonly acknowledged is exercise addiction. Exercise evokes feelings of pleasure and control; the ultimate combination for developing an all-consuming obsession. Like addictions to less healthy alternatives such as drugs and alcohol, your brain starts to crave the neurochemical stimulation associated with intense exercise and the physical results exercise produces. These behaviours convert a once beneficial habit into a harmful routine which can lead to a decline in physical and mental health. The pressures on young people to have an athletic, Instagram-esq image can normalise excessive exercise but the damage of over doing it extends much further than DOMs. So, how does your brain transform a ‘healthy’ lifestyle change into an unhealthy addiction?

I FEEL GOOD! The Chemicals of Exercise

After an exercise session, once you have drunk a litre of water and caught your breath, you normally feel really good. You have a sense of achievement for getting yourself through a tough workout and generally, feel happier and less stressed than you did before the sweat-a-thon. These sensations are generated by the up-regulation of specific chemicals in your brain; stimulating neurons in certain brain regions to evoke those positive feels. Some of these chemicals include:

1. Endorphins: a group of neuropeptides which stimulate opioid receptors. These are the same receptors that are stimulated by some recreational drugs that generate a ‘high’ sensation and prescribed pain-relief medications which promote analgesia. Exercise induces the release of endogenous (‘home-grown’) opioids in the brain which stimulate frontal cortex regions associated with reward and limbic areas responsible for emotional processing. A recent study has described that more intense exercise decreases the selectivity of opioid receptor binding (2), meaning the increased levels of opioids in the brain released due to exercise can stimulate more neurons in frontolimbic areas and boost pleasure sensations.

2. Dopamine: a monoaminergic neurotransmitter which is released before, during and after goal-directed behaviour. Dopamine stimulates neurons in ‘reward’ brain regions in the prefrontal cortex via its release from the ventral tegmental area. Therefore, this neurotransmitter reinforces goal-directed activities by making you ‘feel good’. Exercise increases dopamine levels (3) making you want to come back for more.

3. Serotonin: Another monoamine neurotransmitter which, in the brain, is responsible for regulating mood. Serotonin acts on 5-HT receptors in the forebrain and hippocampus to alleviate anxiety-like behaviours. Experimental studies in animals have demonstrated increased motor activity stimulates the firing of serotonergic neurons (5), triggering its release in the brain. Therefore, exercise lets you leave some of your worries behind

Together, these chemicals drive a happy, stress-free state of mind so post-workout feels are some of the best you can get.

I Just Can’t Get Enough: How Exercise Becomes Addictive

So, we now know how exercise makes us feel good and many people use exercise as a means of stress-relieve and mood-boosting. But too much exercise can create an addiction to these sensations. Addictions manifest due to over-stimulation of reward centres in the brain, resulting in behaviours such as cravings, loss of control and continuing commitment to the source of addiction, despite whether it is healthy or not. Recreational and therapeutic opioids have been extensively studied in animal models to reveal how the brain develops an addiction (6). In summary, taking such drugs makes you feel good as they directly bind to opioid receptors; generating feelings of analgesia while promoting dopamine release; leading to reward sensations and positive-reinforcement of their administration. Withdrawal from such drugs leaves reward regions with lower levels of dopamine and serotonin that the brain is used to, contributing to a negative emotional state and needing larger, more frequent hits to generate the same euphoric sensations.

Although exercise is good for your physical and mental health, the mechanisms of actions within the brain are not completely dissimilar from taking drugs. Each hour-long cardio class, run or weight training session stimulates the release of endorphins due to the ‘stress’ and pain your body has been under. Endorphins bind to opioid receptors, leading to dopamine release to reinforce goal-directed behaviour. This occurs alongside serotonin release which boosts mood, overall leaving you happy and motivated. Once a class is finished and you feel good, you know you can feel the same if you take another class tomorrow. Soon this could turn into two classes per day. Next, back to back classes. Why not throw in a run home? Getting to the gym before class to do 30 minutes on the bike to get even more of a high? All of a sudden, you realise you can’t sleep unless you have run at least 10K that day. This is when exercising gets out of control and can cause huge problems for your health.

In the brain, the chemicals released by exercise as mentioned can above promote addiction through pleasure, motivation and learning. However, not all exercisers develop addictions. It is thought the addictive element to an exercise routine is mainly driven by secondary motives such as trying to attain a certain physique, hit a personal best or to fill a void. If your motivation to exercise revolves around secondary factors, each workout is viewed as goal-directed behaviour. The large hits of dopamine you get post-workout enhances the desire you feel towards these goals due to increased activation of reward-learning regions. Dopamine also plays a role in memory formation so can transform ‘good’ feelings of exercise-associated goal achievements to a learnt behaviour; leading you not just to like exercise but want exercise. This ‘want’ can also be triggered in individuals who have suffered from previous addictions in the past, filling the space of a frowned-upon habit with one many wouldn’t bat an eye at. A study showed around 15% of exercise addicts had addictions to smoking or alcohol (7), and individuals with eating disorders are primed to substitute their calorie-deficit through eating with increased calorie burning through exercise (8). Therefore, it is thought exercise addiction can manifest in certain personality types over others.

Fighting Talk: How to Recognise and Combat Exercise Addiction

Differentiating a healthy and unhealthy relationship with exercise can be difficult for the person in the routine. However, if you are sacrificing social relationships for exercise, working out when injured or feeling completely lousy when you miss a class, your brain may have transitioned your well-intentioned actions into something more sinister. Questions to ask yourself about your exercise routine to check it is still a healthy habit include:

Am I still in control of this routine or is the routine controlling me?

If you are continuing to exercise through injury or other inappropriate times in your life, your routine may have more of a hold over you than you appreciate.

Am I going too hard and do I need to exercise more intensely to feel good?

If you set out to work out for an hour but end up going for two or three regularly can be a sign you are having trouble with exercise. If you feel like you need these extra-long sessions to feel ‘good’, this could be revealing your tolerance to exercise; a common effect of addiction.

Do I constantly think about working out and feel anxious if I am not exercising?

Take a minute to reflect on your thoughts. How often do you think about exercise? Do you spend a lot of time planning and thinking about workouts? And do you feel irritable and anxious when you are out of the gym for an extended period of time? This combination of emotions could be reflecting the craving and withdrawal aspects of addictive behaviour.

If you recognise these symptoms, it is important to consult with a medical professional and voice your concerns. There is an ‘exercise dependence scale’ exam which can indicate if your emotional and psychological relationship with exercise is healthy. No pharmacological interventions exist for exercise addiction but speaking about your underlying motivations for exercising may reveal other phycological symptoms which may be able to be treated. In general, counselling and therapy can be the most useful tool for gaining back control over your exercise routine.

Exercise addiction is still very challenging to pinpoint as we are all actively encouraged to get active. But reflecting on your own routine is important for both your physical and mental health. If you feel like exercise is controlling you, step back and speak to others. No six-pack is worth sacrificing yourself for.







Materials used for this post

1. Health matters: getting every adult active every day

2. Opioid Release after High-Intensity Interval Training in Healthy Human Subjects

3. Regulation of brain function by exercise

4. How to increase serotonin in the human brain without drugs

5. Activity of Serotonergic Neurons in Behaving Animals

6. The Neurobiology of Addiction: Where We Have Been and Where We Are Going

7. Prevalence of the Addictions: A Problem of the Majority or the Minority?

8. Compulsive exercise and eating disorders

9. Exercise Addiction: Literature Review of Behavioural changes

10. Exercise Addiction: Signs and Treatments