Physiology of a Crush

Written by Dr. Anjali Mediboina, House Surgeon, ASRAM

Preoccupation, constant daydreaming, nervousness, rapid heart beat and sometimes out-of-character behavior… Being a medico, I know you’re probably thinking that I’m describing a psychiatric disorder, but actually, I’m describing the symptoms of a crush. 

Recent unfortunate events lead me down a Google spiral which started with the question, what exactly is the definition of a crush?

According to good ol’ Oxford, a crush is defined as: 

“a brief but intense infatuation for someone, especially someone unattainable”. 

Okay, so then what is infatuation? 

“an intense but short-lived passion or admiration for someone or something.”

Okaaay. But then I started wondering… is there any research about crushes and these… feelings? I mean, there has to be, right? 

So I did a PubMed search using the keyword “crush” and, wow there are a lot of papers on crush injuries (fyi for future orthopedic surgeons). So then I decided to search with the keyword “infatuation”, instead, and found 78 papers. 

Now, these results were extremely interesting to read. There was one paper that wrote about “hair steroids in the context of love and separation”, a study by Renner et al[1]., who basically found that single women had higher cortisol levels than women in long-term relationships, and that relationships have a ‘stress-buster’ effect on the body. There was one study by Kuula et al[2]. that associated romantic love with poor sleep quality, depression and anxiety in adolescents, (which I guess is understandable). I found one study that explored “Fictosexuality”, or the love and desire for fictional characters (a rabbit hole I shall explore some other time)[3]. There were also a lot of studies that explored the psychology of stalkers, and found that infatuation was usually a cause for their ‘fixation on the subject’ (yikes). 

Not going to lie, these papers were extremely cool (except for the stalking ones- those were kind of creepy) to read (how did all these researchers get these ideas in the first place?) but what I noticed was, all the papers dealt with “love” and “infatuation”, with no information on the in-between-infatuation-and-love crush feelings. So, I decided to go back to google. Basically, I was searching for the answers to some specific questions: What exactly happens when you have a crush on someone? And, is there a cure to a crush? 

1. Definition 

A crush is a short, brief interest and attraction towards someone. The person is usually someone you don’t know that well, and would like to get to know better. 

2. Mechanism of Action

A. Neurobiological mechanism:

When you see your crush, serotonin levels fall, leading to the release of cortisol. This in turn causes the release of dopamine, and the production of nor-adrenaline. 

  • Due to the fall in serotonin, you will notice a bit of an obsession with your crush; constant thoughts about them, repeated visits to their social media, etc.
  • Dopamine causes feelings of excitement and anxiety, which may manifest as feelings of giddiness.
  • Nor-adrenaline causes increased energy levels and sleeplessness, and may manifest as rapid heart beatsIf you’re up all night thinking about or talking with your crush, it’s because of this particular hormone[4]. 

B. Psychological mechanism

A crush is usually on a person we don’t know that well. According to Dr. Josh Kaplow for Bustle, the person of interest, or the crush, acts as a new stimulus for the brain, and it’s the newness of the person that “keeps us engaged[5]”. 

Have you ever built up a person in your head, imagined scenarios and conversations with them, only to be disappointed when you actually talk to them? This is because crushes are usually rooted in fantasy. To quote Dr. Bukky Kolawole in an interview with Insider, “You have little pieces of information and what you see, you are drawn to in that person[6].” Which is what makes crushes different from actual relationships- crushes are built on what you think you know about that person, while a relationship is built on what you actually know about them. 

Once you get to know about the person, two things may happen- either they end up being exactly how you imagined (which might be rare), or they might not be how you imagined. In the latter case, this is when the feelings start to ebb and your crush may fade. 

3. Clinical Features

Some common features experienced are: 

  • Raised heart rate and respiratory rate
  • Excitement and anxiety
  • Insomnia and restlessness
  • Constant thoughts of your crush

4. Treatment

There appears to be no exact treatment for a crush. Generally, if one-sided, the feelings tend to fade away. 

However, there have been papers by Castillo-Romero et al. and Shoja et al. who have found that the pineal gland products, melatonin and vasotocin, appear to inhibit neural activity in the caudate-putamen region, that is the region responsible for love and affection[7,8]. Thus, the hypothesis is that melatonin and vasotocin might play a role in attenuating romantic feelings. 

A paper titled the Ethnopharmacology of Love, by Leonti et al., explored the herbal cures for lovesickness mentioned in literature folklore, and found that while there are foods which induce feelings of attraction (or aphrodisiacs), there aren’t as many which do the opposite[9]. At most, there are foods which sedate or have toxic effects; the closest anaphrodisiac food they found was the Mentha sps., which appears to be associated with decreasing testosterone levels. 

Final thoughts

I think the takeaway would be that it’s not the crush, but rather the feelings of the crush that’s so addictive (thanks to the dopamine), and that the only cure is a healthy dose of reality, usually provided by your friends. 

Another cure would probably be reading this post, I know writing it cured me :p 


1. Renner J, Stanulla M, Walther A, Schindler L. CortiLove: A pilot study on hair steroids in the context of being in love and separation. Comprehensive Psychoneuroendocrinology. 2021 Aug 1;7:100061.

2. Kuula L, Partonen T, Pesonen AK. Emotions relating to romantic love—further disruptors of adolescent sleep. Sleep Health. 2020 Apr 1;6(2):159-65.

3. Karhulahti VM, Välisalo T. Fictosexuality, Fictoromance, and Fictophilia: A Qualitative Study of Love and Desire for Fictional Characters. Frontiers in Psychology. 2021 Jan 12;11:575427.

4. Fabello M. The Neurobiology Behind All The Ridiculous Things You Do When You’re In Love. Everyday Feminsim [Internet]. 2012 Dec, 8. Available from:

5. Steber C. What Happens To Your Brain When You Have A Crush on Someone. Bustle [Internet]. 2020 Feb, 24. Available from:,excited%20and%20giddy%2C%20Mica%20says.

6. Naftulin J. Here’s Why YOu Develop Crushes, According to Science. Insider [Internet]. 2018 Dec, 5. Available from:

7. Castillo‐Romero JL, Vives‐Montero F, Reiter RJ, Acuña‐Castroviejo D. Pineal modulation of the rat caudate‐putamen spontaneous neuronal activity: Roles of melatonin and vasotocin. Journal of pineal research. 1993 Oct;15(3):147-52.

8. Shoja MM, Tubbs RS, Ansarin K. A cure for infatuation?: The potential’therapeutic’role of pineal gland products such as melatonin and vasotocin in attenuating romantic love. Medical hypotheses. 2007 Mar 5;68(5):1172-3.

9. Leonti M, Casu L. Ethnopharmacology of love. Frontiers in pharmacology. 2018:567.

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