When we feel anxious, our body switches on an automatic safety system called the fight-or-flight response. Some people also freeze when this happens. This response is designed to protect us from danger.
In simple terms, your body thinks something might be unsafe and gets you ready to react quickly.
Millions of years ago, early humans needed this response to survive real dangers. Today the threats are usually different – things like a loud noise at night, a difficult conversation, or a stressful event. But our body reacts in the same way.
You might notice:
- faster breathing to bring in more oxygen
- a racing heart to send blood to your muscles
- tense or shaky muscles
- “butterflies” or nausea as blood moves away from digestion
- difficulty thinking clearly or taking in what people are saying
These changes can feel uncomfortable, but they usually settle once your body realises you’re safe.
Watch our Flight or fight animation to learn more about anxiety and the threat response.
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Download our Flight or fight diagram as a pdf:
Flight or fight response
Last updated: February 2026