What happens in your brain during a panic attack?

A panic attack can feel like your body has turned against you. Your heart pounds, your chest tightens, the air will not seem to reach your lungs, and you become certain that something is badly wrong. Within minutes it peaks, and then, slowly, it passes, leaving you drained and unsure of what just happened.

What happened is a false alarm. Your brain's threat system detected danger where there was none and launched the full defense response it would use if the danger were real. Understanding how that alarm is wired explains why panic feels so physical, why it can arrive out of nowhere, and why, for many women, it seems to keep to a calendar.

What a panic attack is, and what it isn't

The diagnostic manual used by clinicians, the DSM-5 (American Psychiatric Association, 2013), defines a panic attack as an abrupt surge of intense fear or discomfort that peaks within minutes. During that surge, at least four of thirteen experiences appear together: a pounding or racing heart, sweating, trembling, shortness of breath, a choking sensation, chest pain, nausea, dizziness, chills or heat, numbness or tingling, a sense of unreality, fear of losing control, and fear of dying.

Panic attacks are far more common than most people assume. In the US National Comorbidity Survey Replication, Kessler et al. (2006) interviewed 9,282 adults and found that 22.7% had experienced panic attacks without ever developing panic disorder, while 4.8% met the criteria for panic disorder itself. A single panic attack, or even several, is not a diagnosis. Panic disorder describes recurrent, unexpected attacks followed by at least a month of persistent worry about the next one, or changes in how you live to avoid them.

Panic disorder is also not evenly distributed. Eaton et al. (1994) found it roughly 2.5 times more common in women than in men, and in an analysis of the same national dataset, Sheikh and colleagues (2002) found that women with panic disorder were more likely than men to report breathing-related experiences such as shortness of breath during attacks. That detail matters, and we will come back to it.

If you have never had a panic attack before, or if you have chest pain you are unsure about, get checked urgently. Panic and heart problems can feel alike, and only a clinician can tell them apart.

Your brain's threat network

Your brain has a dedicated network for detecting danger and preparing your body to survive it. Gorman et al. (2000) described this "fear network" in their revised neuroanatomical model of panic disorder, which remains one of the most cited frameworks in the field.

At its center sits the amygdala, a pair of almond-shaped structures deep in each temporal lobe that assesses incoming information for threat. The amygdala works with the hippocampus, which supplies context (have I been here before, was it dangerous?), and the medial prefrontal cortex, which helps decide whether the alarm is warranted and applies the brakes when it is not.

When the amygdala sounds the alarm, it sends signals to a set of downstream targets, and each one produces a part of what you feel:

• The hypothalamus activates your stress hormone system, releasing cortisol.
• The locus coeruleus in the brainstem releases noradrenaline, raising your heart rate, blood pressure and alertness.
• The periaqueductal gray coordinates defensive behavior, the urge to freeze or escape.
• The parabrachial nucleus speeds up your breathing.

This is why panic is so physical. Each sensation maps to a specific circuit doing exactly what it evolved to do. The experience is not imagined. It is a real activation of real brain systems, triggered at the wrong moment.

Gorman's model also points to the prefrontal cortex as part of the problem. When the cortex misreads normal bodily sensations, interpreting a skipped heartbeat as a heart attack or a moment of breathlessness as suffocation, it can feed the amygdala more evidence of danger. Clark (1986) described this as the vicious circle at the core of panic: a sensation is interpreted as a catastrophe, the interpretation raises anxiety, anxiety intensifies the sensation, and the loop accelerates.

The alarm that listens to your body

Most fear responds to something outside you: a snake, a near miss on the road. Panic is different, because the trigger is often inside.

Klein (1993) proposed that panic disorder involves a "false suffocation alarm," a monitoring system in the brain that tracks signs of oxygen shortage, such as rising carbon dioxide (CO2), and that may be set too sensitively in people prone to panic. One line of evidence for this comes from laboratory studies in which participants take a single breath of air enriched with 35% CO2. In people with panic disorder, that one breath provokes panic far more readily than in people without it.

Two studies from the University of Iowa then located parts of this alarm in the brain. Ziemann et al. (2009) showed in mice that the amygdala itself is a chemical sensor: inhaled CO2 makes the brain slightly more acidic, and an acid-sensing channel called ASIC1a in the amygdala detects that change and triggers fear behavior. Mice without the channel showed much less CO2-evoked fear, and restoring it in the amygdala brought the response back.

Feinstein et al. (2013) then tested three women with damage to the amygdala on both sides of the brain, including a patient known as SM, who does not experience fear in response to snakes, spiders or horror films. After one breath of 35% CO2, all three had full panic attacks, a feeling they described as entirely new to them. Only 3 of 12 comparison participants with intact brains panicked.

The finding was striking: the brain region most associated with fear was not needed for panic. The authors concluded that the amygdala filters threats from the outside world, but internal danger signals can trigger panic through other routes, most likely in the brainstem. This may help explain why panic can arrive "out of the blue." The trigger was there. It just came from inside your body, below the level of conscious thought.

Why panic can follow your cycle

If you have noticed that panic attacks cluster in the days before or around your period, there is a biological reason that pattern is plausible.

Your brain's main brake is gamma-aminobutyric acid (GABA), the inhibitory signal that quiets neural activity. During the second half of your cycle, progesterone is converted into allopregnanolone, a neurosteroid that enhances GABA's calming effect at GABA-A receptors. When progesterone falls before your period, allopregnanolone falls with it. Lovick (2006) showed in animal studies that it is this rapid withdrawal, rather than low levels in themselves, that reshapes GABA-A receptors in the brain regions that govern anxiety.

This system appears to be directly involved in panic. Ströhle et al. (2003) induced panic attacks in a laboratory setting and found that levels of allopregnanolone and related neurosteroids dropped in people with panic disorder, but not in healthy controls. In other words, in panic disorder, the brain's own calming chemistry may move in the wrong direction at exactly the wrong moment.

The CO2 alarm may shift across the cycle too. Perna et al. (1995) gave the 35% CO2 test to 10 women with panic disorder at two points in their cycles. They reported significantly more anxiety in the early follicular phase, the first days of bleeding just after progesterone has dropped, than in the mid-luteal phase, when progesterone is at its highest. Women without panic disorder showed no reaction in either phase.

How this plays out in daily life is less settled. Kaspi et al. (1994) found that around half of the women with panic disorder they studied had worse panic premenstrually, a pattern they confirmed with daily tracking in a subsample. Reviewing the wider literature, Nillni et al. (2021) found that women with panic disorder consistently report more frequent and severe attacks before their period when asked to look back, but prospective studies that track experiences day by day have produced mixed results. Some find a clear premenstrual increase; others find none.

The honest reading is that some women's panic follows their cycle closely and others' does not, and memory alone is not a reliable way to tell which group you are in. That is exactly why tracking matters.

What helps, and why it works in the brain

The good news is that panic disorder is one of the most treatable conditions in mental health. In the UK, NICE guidelines (2011, CG113) recommend cognitive behavioral therapy (CBT), usually 7 to 14 hours in total over up to four months, as the treatment whose benefits last longest. When medication is chosen, the first choice is a selective serotonin reuptake inhibitor (SSRI) licensed for panic disorder. NICE advises against benzodiazepines for panic disorder, because their long-term outcomes are worse.

Gorman et al. (2000) proposed that these treatments act on different parts of the same network. CBT works "upstream," strengthening the prefrontal cortex's control over the amygdala and weakening the learned link between bodily sensations and catastrophe. A core part of CBT for panic is deliberately and safely bringing on the sensations you fear, such as a racing heart after running on the spot, so your brain can relearn that they are not dangerous. SSRIs, in contrast, appear to calm the network from within, reducing the reactivity of the amygdala and its downstream alarm centers in the brainstem.

Both are examples of the brain's capacity to change. Panic is a learned pattern in a living network, and learned patterns can be gradually retrained. This takes weeks to months rather than days, but the retraining is real.

Where brain stimulation fits

Because panic involves a prefrontal brake that is not braking hard enough, researchers have asked whether gentle electrical stimulation of the prefrontal cortex could help. The mechanism is plausible. Ironside et al. (2019) found that prefrontal stimulation reduced the amygdala's response to threatening faces in people with high trait anxiety.

For panic disorder specifically, though, the evidence is early.

Anxiety that is tied to hormonal change is a different picture from panic disorder. Many Samphire users use their headband to manage anxiety linked to their menstrual cycle and to perimenopause, and tell us it has become part of how they handle the weeks they know will be harder. Our article on anxiety before your period covers the evidence and the open questions in more depth.

What you can do now

Start with a record. Note the date of each panic attack, what you were doing, and where you were in your cycle, and keep going for at least two cycles. If your attacks cluster in the days before or just after your period starts, that is valuable information for a clinician and may point toward conditions such as premenstrual dysphoric disorder (PMDD) or premenstrual exacerbation, which are managed differently. You can use the Samphire app to log panic attacks alongside your cycle and see whether a pattern emerges.

Then bring that record to your GP or clinician. CBT and medication are both effective, and many people need some combination of the two. If you have found a pattern, say so: the timing of your attacks can shape the plan.

In the moment itself, it can help to remember what you now know about your brain. A panic attack is an alarm, not a verdict. It peaks within minutes and then subsides, because the systems that produce it cannot sustain that level of activation for long.

The 5-4-3-2-1 method

One approach many people find useful during a panic attack is the 5-4-3-2-1 grounding method. Slowly, and one sense at a time, name:

• Five things you can see.
• Four things you can touch.
• Three things you can hear.
• Two things you can smell.
• One thing you can taste.

The method works with the circuitry described above rather than against it. During panic, your attention is pulled inward, toward your heartbeat and your breathing, and every sensation you notice feeds the loop Clark (1986) described. Deliberately naming what is around you redirects attention to the outside world and gives your prefrontal cortex a structured task, which may help it reassert its brake on the alarm. It is worth being clear about the evidence: grounding is widely taught in clinical practice, but the 5-4-3-2-1 sequence itself has not been tested in large controlled trials. Think of it as a way through the next few minutes, not a replacement for treatment.

A false alarm can be retuned

Panic attacks were long described as "nerves," as if they were a matter of temperament. The research describes something more specific: a threat network that responds to internal signals, a calming system that depends partly on the neurosteroids your cycle produces, and a prefrontal brake that can be strengthened with the right treatment.

There is still a great deal to learn, particularly about how the menstrual cycle shapes panic in individual women. But a false alarm in a well-mapped circuit is something that can be understood, tracked and, over time, retuned.

This article is for information only and is not medical advice. If you are worried about panic attacks or any new physical experiences, speak to a healthcare professional.