The Abridged version:
- To understand the physiological effects of love, we need to understand cortisol, known as “the stress hormone.”
- According to a recent study, couples sharing positive emotions can reduce cortisol levels in the body.
- Attachment styles also play a role in how our bodies react to feelings of love.
Most of us know what love feels like in our bodies but what does it actually do to us neurologically and physically? What are the butterflies we get when we fall for someone new or those devastating pits in our stomach when we’re going through a de-escalation or breakup? So much of what R&B songs are based on is neurochemical. Generally it’s some combination of dopamine, oxytocin and cortisol to blame for our hearts fluttering or our stomachs sinking.
I started my exploration with a study led by Tomiko Yoneda, UC Davis assistant professor of psychology.
We talk a lot about dopamine, oxytocin, serotonin and endorphins, but in order to understand Yoneda’s research, we need to understand cortisol. Cortisol is commonly known as “the stress hormone,” but that’s a little reductive.
Cortisol helps us manage emergencies in our bodies. For example, if you get into a car accident, your cortisol spikes and makes you more alert and helps you stay aware of your environment to readjust. The issues come when cortisol spikes last too long. That’s when cortisol can wreak havoc on our nervous systems.
When our nervous systems are unregulated for too long a few things begin to happen neurologically. The hippocampus shrinks, which is where we contextualize fear and form memory. The amygdala becomes overactivated, which makes things feel urgent, personal and dangerous. Serotonin, which regulates confidence, mood stability and perspective, gets disrupted. And dopamine plummets, making motivation feel more like effort than excitement.
An elevated nervous system also sends the body into what researchers sometimes call survival budgeting. This often shows up as brain fog, digestive issues, low libido, chronic muscle tension and shallow sleep. When the body enters survival budgeting, it starts treating joy as something it cannot afford. This is when we begin to mistake intensity for intimacy and urgency for love. Connection starts to feel dangerous, and familiarity gets misread as safety. This is one reason so many of us stay in unhealthy relational patterns longer than we want to.
Established love and cortisol
Yoneda’s study, published in August in the American Psychological Association’s Journal of Personality and Social Psychology, found that when older, established couples experience positive emotions together, their bodies show measurably lower cortisol levels than positive experiences by themselves. “We defined shared positive emotions as moments when both partners reported higher positive emotions than their own typical levels, and they were together,” Yoneda explained. “In our study, shared positive emotions lowered cortisol by about 1.03 nanomoles per liter.” That is, shared positive emotions lowered cortisol by nearly half as much as a common stress test raises it.
“That reduction is over and above the effect of individually experienced positive emotions. We’re already accounting for that,” Yoneda said. “These positive effects on cortisol lasted throughout significant periods of the day.”
Yoneda’s test group was older couples, but what does this research mean for younger or newer couples? What might it mean for non-romantic loving relationships? “These benefits might extend beyond spouses,” she said. “Friends, coworkers, even strangers. We haven’t studied that yet, but the theory would suggest it.”
New love and cortisol
When we fall in love, our neurochemicals whip into a frenzy. Dopamine and oxytocin provide the anticipation and connection your favorite love songs are made of. You can’t stop looking at your phone to see if they’ve texted or DM’d you and every conversation makes you feel closer to them. On the other hand any inconsistency, mixed signals or uneven investment create an opening for cortisol to creep in and start dysregulating our nervous systems.
One of the most important factors scientifically when it comes to love and the nervous system is attachment style. Attachment styles are basically operating systems that we learned young via experiences and trauma and that our nervous systems still run in regards to love. Your attachment style decides whether silence feels neutral, soothing or terrifying. The same unanswered text can register as “they’re busy,” “they need space” or “I’m being abandoned,” depending on the nervous system.
There are four main attachment styles: secure, anxious, avoidant and disorganized. Secure says, “I can love, be close, and be OK.” Anxious says, “I might lose you. Stay close.” Avoidant says, “I might lose me if I get too close.” And disorganized is a combination of avoidant and anxious at the same time.
When attachment styles are mismatched it can send cortisol spiking through the roof. For instance, in an anxious-avoidant pairing, the avoidant partner’s need for space can trigger fear in the anxious attachment’s nervous system because they fear being abandoned. Even secure systems can become dysregulated inside inconsistent relationships where needs go uncommunicated or unresolved.
Cortisol and the ‘glow-up’
It’s common for people to go through a “glow-up” in a new relationship or after a breakup. This is also largely due to cortisol. When cortisol drops, the body reallocates resources back to our long-term health. Skin improves. Inflammation lowers. Sleep deepens. Digestion stabilizes. Motivation returns.
New love can do this temporarily because novelty, attention and attunement lower stress. Breakups can also do this once the first harsh spike of cortisol is over, especially if the relationship itself was chronically dysregulating.
The glow-up isn’t about the new person specifically. It’s about the nervous system finally exhaling. Sustainable love doesn’t spike your chemistry. It stabilizes it.
The great joy hint
Love isn’t just a feeling, it’s a physiological environment. Who you attach to trains your nervous system. Joy isn’t just romance. It’s care, communication and co-regulation.
Try once a day intentionally sharing a positive emotion while spending time with your partner. Not a big date. Something small and joy-filled. Go for a walk. Watch a show. Send some memes back and forth. Do something that brings you both to the present moment together.
A lot of couples only truly come together on purpose when something is wrong. That’s like watering a plant once it starts wilting. Shared joy trains your nervous system to feel safe before conflict arrives. Just like Yoneda’s research shows, shared joy lowers cortisol more effectively than joy experienced alone.
Romantic chemistry isn’t just sparks. It’s the nervous system recognizing a place it can rest.
Andru Defeye is the former poet laureate of Sacramento and a regular contributor, writing The Great Joy Hunt for Abridged.