Trauma triggers: why a smell or a tone of voice brings it all back

She was standing in the queue at the till when a man in a dark coat walked past. She barely saw him. She only caught the smell — sharp, sweetish, a cologne she hadn’t come across in twenty years. The next moment her heart was pounding, her palms were wet and there was a rushing in her ears. She left her basket on the floor and walked out. Only in the car park did she understand what had happened: that was how her stepfather used to smell.

People who have experienced something like this often say: “I know it’s silly.” It isn’t silly. It is a trigger — a stimulus that opens up, in body and mind, something that happened long ago, and opens it as if it were happening right now. In this post I will explain why smells, sounds and tones of voice in particular have such power, why the body responds faster than thought, and what you can do so that triggers slowly lose their hold over your day.

What a trigger is and what it isn’t

The word “triggered” has spread into everyday language in recent years. People say they were triggered by a comment on social media or by a relative’s political opinion. I understand why — the word is handy. But in conversations about trauma it means something more precise.

A trigger in the narrower sense is a stimulus that was once linked to a traumatic event and that today, often without any conscious connection, calls up part of the original experience: a bodily alarm, an emotion, an image, a sense of helplessness. It isn’t just unpleasant. It is returning. For a moment the person isn’t responding to the present, but to a past that has leapt into the present. You will find a short explanation of the term in the knowledge base under trigger.

Traumatic experiences are not the exception we sometimes imagine. In a large World Health Organization survey covering respondents from more than twenty countries, more than 70 per cent of people reported having experienced at least one event that counts as traumatic. For most, this leaves no lasting consequences. For some, though, triggers remain — invisible threads leading back.

I described in more detail what counts as trauma, and why it doesn’t depend only on how “bad” the event was, in How trauma stays written in the body — and how the body can let it go. Here I will focus mainly on how the past comes back.

Why smell in particular

Of all the senses, smell has a special route to memory and emotion. Signals from the olfactory cells travel from the olfactory bulb relatively directly to the brain areas linked with emotion and memory — the amygdala and the region around the hippocampus. Most other sensory information passes first through the thalamus, a kind of relay station. Smell has a shortcut.

The psychologist Rachel Herz and her colleagues studied memories evoked by smells and compared them with memories evoked by pictures or words. Memories triggered by smell were not necessarily more accurate, but they were more emotional, and people more often reported a sense of truly being “taken back” to that moment. This is exactly what confuses people about triggers: a smell doesn’t call up a story, it calls up a state.

Tone of voice works in a similar way. Tone is one of the first signals we learn to read as babies — long before words. A child who grew up with an unpredictable parent learns to recognise in a split second whether “that” tone announces danger. Back then, this skill was essential. As an adult, you can’t simply switch it off.

A memory without a time stamp

Why does a traumatic memory return differently from an ordinary one? In an influential model of post-traumatic stress disorder, Anke Ehlers and David Clark proposed an answer that a great deal of research now supports. An ordinary memory is embedded in a story: we know when it happened, where, what came before and what came after. A trauma memory, however, is often stored in fragments — as a collection of sensory pieces without a clear place in time.

These pieces are tightly linked to the stimuli that were present then: a smell, a sound, light, the position of the body. When one of them appears today, the brain recognises it faster and more easily than other things — researchers talk about strong perceptual “priming”. And because the memory has no time stamp, it doesn’t appear as “this happened then” but as “this is happening now”. Chris Brewin and colleagues similarly showed that intrusive images in trauma are more sensory and less anchored in context than ordinary memories.

This also explains why understanding alone isn’t enough. You can know perfectly well that the man in the coat is a stranger and that your stepfather is no longer in your life. The body is faster than that knowledge.

The body reacts before you think

The neuroscientist Joseph LeDoux described how the amygdala can set off a defensive response before the conscious part of the brain has even recognised the stimulus. This fast route trades accuracy for speed: better ten false alarms over a stick than to miss a snake once. I wrote more about what happens in the brain during fear in What happens in the brain during anxiety — and why the body reacts before you think.

In people with a traumatic experience, this alarm is often set to be more sensitive. We call this hypervigilance — a constant, often unconscious readiness for danger. Someone who is hypervigilant notices every change in a face, every footstep in the corridor, every silence that lasts a little too long. And because attention is already turned outwards, triggers find their way in more easily.

The response to a trigger isn’t always panic. For some it is anger, for others tears, for others shame. And for some the response is the opposite — instead of arousal comes numbness, withdrawal, the feeling of not being in the room. I wrote about this second response in Dissociation: when you switch off to survive.

Four families of triggers

When people think of triggers, they usually picture something external and obvious: the sound of a siren, a scene in a film, a place where something happened. But triggers are often much quieter. It helps to sort them into a few groups.

Time-related triggers are particularly interesting. People often don’t know why they are restless every November until they realise that an accident or a loss happened then. Or parents notice that something suddenly began gnawing at them when their child reached exactly the age they themselves were when something terrible happened to them. The body keeps count, even when the head doesn’t.

And internal triggers are the most insidious. A racing heartbeat after running up the stairs can feel exactly like the one a person felt in danger — and the body responds to the heartbeat, not to the stairs. That is why some people feel their distress comes “out of nowhere”.

Tone of voice in a relationship

As a therapist in training under supervision in marriage and family therapy, I notice that many triggers fire precisely in our closest relationships. That is no surprise: the most common wounds were made in relationships, and it is in relationships that they most easily reopen. The partner often doesn’t know this. They only see that a perfectly ordinary sentence of theirs caused a stormy reaction, and they feel guilty or misunderstood.

A moment like that might sound like this (composed, not a real person):

“I only asked why the dishes weren’t done yet. Normally.”
“It wasn’t normal. You said ‘why’ the way Dad used to say it, right before he started.”
“But I’m not your dad.”
“I know. My head knows. My body had already hidden.”

In relational family therapy, which I am training in, a moment like this is not a mistake to be fixed as quickly as possible. It is a window. It shows where one person’s past meets both partners’ present. It often helps the partner a great deal to understand that the reaction is not a verdict on them but an echo of something older. And it helps the person who has been triggered to be able to say so without having to defend themselves.

At the same time, it matters that a trigger doesn’t become a weapon or an excuse. “You can’t say that to me, because it triggers me” can shut down a conversation that needs to happen. The aim is not for the partner to walk on eggshells, but for both to understand what is going on and find a way together that is neither panic nor silence. A similar pattern, where a partner’s silence sets off an inner alarm, is described in Anxious attachment: why a partner’s silence sets off the alarm.

Why avoidance doesn’t help in the long run

The most natural response to triggers is avoidance. I don’t go to that shop any more. I don’t listen to that music any more. I don’t walk down that street. And in the short term it works: fewer alarms, a calmer day.

But avoidance has a price. The world slowly narrows. More and more places, people and situations become “too much”. And most importantly: the brain never learns that the trigger is no longer a danger today. Every time you avoid it, you confirm it was dangerous. Ehlers and Clark described avoidance, suppressing thoughts and constantly checking for danger as precisely the behaviours that keep the difficulties going. You can read more about this mechanism in Anxiety and avoidance: why avoiding helps you today and harms you tomorrow.

This doesn’t mean you should deliberately expose yourself to triggers on your own and by force. It only means the sensible path is slow, considered and often supported by a professional: a gradual approach in which you stay within the range you can still manage — within your window of tolerance.

Exercise: a map of your triggers

The first step towards triggers losing their power is knowing them. Not so that you can avoid them, but so that they don’t take you by surprise. You can do this exercise today, with a pencil and a sheet of paper. If you’d like some structure, the map of your triggers tool will help.

1. Recall the last moment you reacted more strongly than the situation called for. Don’t choose the worst memory — choose something in the middle.
2. Write down what you perceived just before. A smell, a sound, a tone, a word, a facial expression, a sensation in your body, the time of day. Be precise, even if it seems unimportant.
3. Write down what happened in your body. Where did you feel it? Was it arousal — heart, heat, tension — or withdrawal — emptiness, numbness?
4. Ask yourself: how old was I in that moment? Not in reality, but by feel. The answer often tells you where the trigger comes from.
5. Write down one thing that would help you stay in the present next time. A long out-breath, feet on the floor, a sentence you say to yourself: “This is now, not then.”

If the exercise starts to pull you in too deep, stop. Stand up, look around the room, name something you can see. The exercise is meant for observing, not for reliving.

What helps, and when to look for a specialist

When triggers are frequent and strong, when there are nightmares, flashbacks or constant tension, this may be a sign of post-traumatic stress disorder. That diagnosis is made by a doctor or clinical psychologist, not by an online questionnaire and not by me.

There are methods for processing traumatic memories with good research support: trauma-focused cognitive behavioural therapy, cognitive therapy for PTSD developed by Ehlers and Clark themselves, prolonged exposure and EMDR. How the last of these works is explained in EMDR therapy: how it works and who it is for. Alongside these there are somatic methods that work through bodily awareness. All of these methods require specialist training. I don’t practise them and I don’t present myself as a trauma specialist. If you recognise severe and frequent reactions in yourself, look for a psychotherapist specifically trained in trauma work, or talk to your GP or a psychiatrist.

What therapy that isn’t trauma-specialised can also offer is a space in which you notice your triggers and understand how they affect your relationships. When they play out in a partnership or a family, it is often valuable for those who witness them to talk about them too.

If a trigger ever pulls you into such distress that you can’t see a way out, or if thoughts of self-harm appear, don’t stay alone. In Slovenia you can call the crisis line Klic v duševni stiski on 01 520 99 00 (every day from 7 pm to 7 am), the Samarijan helpline on 116 123 (24 hours a day) and, in an emergency, 112. If violence is still part of your life, the SOS helpline for women and children victims of violence in Slovenia is available on 080 11 55, and the police on 113. A trigger that warns of a danger that is still present isn’t the past — it calls for safety first, and only then therapy.

Where this explanation doesn’t apply

Not every discomfort is a trigger. If an unfair comment makes you angry or sad news makes you sad, that is an ordinary emotional response. A trigger in the narrower sense is a response out of proportion to the present and stamped with the past. If we call everything unpleasant a trigger, the word loses its meaning — and those who truly experience trauma returning find it harder to be understood.

Content warnings don’t work the way we would like. Payton Jones, Benjamin Bellet and Richard McNally studied what warnings before difficult content do for people with a history of trauma. The warnings didn’t reduce distress while reading. But they did point to something else: in participants they strengthened the belief that trauma was a central part of their identity. A later meta-analysis found something similar: warnings don’t reduce distress during the content, but can increase anxiety beforehand. This doesn’t mean consideration is pointless — it means real safety is built differently: through understanding and gradual approach, not through faster avoidance.

Not every strong reaction is a sign of trauma. Some people are by nature more sensitive to sounds, smells or change. Some have physical conditions that speed up the heart rate or affect mood. With recurring physical symptoms, it is wise to check your health with a doctor first.

And trauma is not something that has to make you stronger. People are sometimes ashamed that after years a smell or a voice “still” triggers them — as if they should be over it by now. The post “What doesn’t kill you makes you stronger” — why that isn’t true of trauma explains why this expectation is unfair. Triggers aren’t a sign of weakness. They are a sign that you survived something.

What to remember

• A trigger is a stimulus that calls up part of a traumatic experience as if it were happening now — with an alarm in the body, an emotion or a withdrawal.
• Smell has a shortcut to emotion and memory, and we learnt to read tone of voice before we understood words.
• A traumatic memory often has no time stamp, so the body reacts faster than the head knows the past is over.
• Avoidance helps in the short term but narrows the world in the long term. What helps is a gradual, supported approach within a range you can manage.
• With frequent and strong reactions, see a doctor and a psychotherapist trained in trauma work.