How Love Affects The Nervous System – Not Just The Heart

Have you ever had an interaction with a friend or partner that left your stomach in knots? Have you ever felt like you were constantly walking on eggshells around them, wondering why you felt so exhausted all the time? Sometimes your body notices a relationship is unsafe before your mind does.

Our interpersonal relationships affect us far more deeply than we often realise, and it’s usually the nervous system that feels the biggest impact.

The nervous system is the body’s internal command centre, constantly scanning your environment for safety or danger and adjusting your physical state accordingly.

The nervous system responds to stress in a few different ways. You’ve probably heard of fight, flight and freeze. This is the body’s automatic survival response. When your body senses danger, adrenaline and cortisol flood the body. Fight prepares you to confront a threat, flight mobilises you to escape danger, and freeze shuts the body down in response to overwhelming stress.

Regulation has been a really popular word in wellness content recently. It refers to the nervous system’s ability to find balance. Depending on the situation, regulation can cause you to feel alert and active (for example, while driving), or it can help you achieve a more restful state.

The nervous system can be triggered in both positive and negative ways. Safety signals are positive sensory cues for the nervous system that inform your brain and body it’s safe. This can be triggered by things like a calm tone of voice, warm eye contact and relaxed posture.

This is where interpersonal relationships come into play through co-regulation. Human beings are biologically wired to share nervous system states, which is why a compassionate conversation with a caring friend can de-escalate anxiety without you even realising it.

But what happens to our nervous system when we surround ourselves with toxic relationships? Chronic emotional instability places the nervous system under continuous stress. When we exist in constant states of emotional chaos, the brain perceives this as a threat to survival and goes into overdrive.

But what exactly is going on inside that brain of yours? Well firstly, you’re put into a state of constant hypervigilance. The brain’s threat detector (the amygdala) stays permanently turned on, always scanning for danger or potential threats like a change in tone of voice, facial expressions or body language. This often manifests as the feeling of “walking on eggshells,” where the body is trapped in a chronic “fight-or-flight” mode. After a period of enduring this, your nervous system loses its ability to calm down and instead, you get stuck into a state of high alert.

The hormonal system is also heavily affected by toxic relationships. Your adrenal glands continuously pump out stress hormones, useful for short bursts of danger. But long-term exposure to high levels of cortisol and adrenaline can physically damage the body. Over time, this can increase inflammation throughout the body. Constantly producing stress hormones is exhausting. Over time, this can lead to chronic fatigue, as the nervous system spends enormous amounts of energy managing anxiety and fear.

The physical toll of a toxic relationship can even affect one’s sleep as high cortisol blocks the production of melatonin (the sleep hormone). This means you can’t achieve a deep restorative sleep that the brain needs for proper function.

As horrible as it all sounds, many people find themselves unable to resist these toxic relationships, which can be a result of an emotional addiction to the inconsistency. Toxic relationships are often defined by a rollercoaster of extreme lows (like fighting, silent treatment) and extreme highs (love bombing and gestures).

This triggers intermittent reinforcement, the same schedule in your brain that causes gambling addictions. When things are bad, you’re desperate for a “fix” of good again, creating powerful dopamine-reward patterns in the brain. As a result, the brain can begin associating emotional relief with the return of affection or reassurance. This chemical rollercoaster can make it physically painful and incredibly difficult to leave, even if you know better.

When people find the courage to leave a toxic relationship or friendship and enter a stable, healthy one, they can find themselves dealing with a range of unsettling, confusing emotions such as boredom.

But why is this so? For the person in an unstable relationship, the partnership feels like an intense chemical rollercoaster, which can be mistaken for “passion” or “chemistry.” In a healthy relationship, the highs and lows are replaced by a steady, predictable baseline. Because your brain is no longer receiving massive erratic spikes of dopamine and adrenaline, it can feel like there is something “missing” from the relationship.

This is because your body has adapted to the stress and becomes its new normal. After spending months or years in a state of hypervigilance, a heightened state of stress and anxiety feels more familiar. When you finally enter a safe environment, the sudden drop in stress hormones feels foreign. To a dysregulated nervous system, unfamiliarity can feel threatening, which is often misinterpreted as boredom.

In toxic environments, the brain is familiar with predicting the unpredictable and constantly walking on eggshells, causing a mental loop in which the brain becomes highly efficient at solving problems, managing crises and chasing validation. On the other hand, in an emotionally safe environment, there are no constant threats or crises. This can feel unsettling for a brain that has become accustomed to high-stakes survival states.

This phenomenon is deeply rooted in attachment theory, particularly for those with anxious attachment styles dating someone with an avoidant attachment style. The avoidant pulls away, which triggers the anxious person’s deep fear of abandonment. They chase harder, and when the avoidant briefly returns, the anxious person feels a massive wave of relief.

On the other hand, when an anxiously attached person meets a secure partner, there is no game of cat and mouse. Because the anxious person’s abandonment triggers aren’t activated, they mistake the absence of anxiety for boredom.

In a world where women are less financially dependent on men in relationships, emotional safety is emerging as a powerful modern standard for attraction. People are increasingly choosing “peace” over the chaotic “butterflies.”

Historically, media and pop culture taught us that love should feel like racing hearts, sweaty palms and emotional intensity. Experts now suggest that “butterflies” can sometimes be a nervous system response to anxiety, uncertainty, and fear of rejection disguised as attraction. Increasingly, people are beginning to associate genuine attraction with a sense of calm rather than chaos. Choosing a partner who reflects this can be a sign of emotional maturity and self-worth.

Emotional safety means that the hypervigilance from the toxic dynamic eventually quietens down. When you don’t have to walk on eggshells, your mental energy becomes yours again.

Biologically, it becomes difficult for the body to experience genuine connection while stuck in fight-or-flight mode. When your nervous system is calm, your body is able to release oxytocin (the bonding hormone), which creates a steady, enduring warmth rather than fleeting butterflies.

Love was never supposed to feel like survival mode. Sometimes the body recognises danger long before the mind is ready to acknowledge it.

If this resonates with you or someone you know, support is available through the Women’s Aid hotline at 1800 341 900.

Words by Katie Walsh