Fight-or-flight response

What is fight-or-flight response?

When your brain senses a threat, your body releases adrenaline and cortisol. Your heart beats faster. Breathing speeds up, muscles tense, and digestion slows. Walter Cannon, a physiologist at Harvard, described this response in 1915. Freezing, where you go still, is part of the same system.

Key things to know

It's useful in real danger. That's what it's for. Problems start when it switches on for exams, emails, or social situations, or when it stays on for weeks at a time and your body never really gets the signal that you're safe again. Ongoing activation is linked with anxiety, panic attacks, poor sleep, and burnout.

• It's an automatic survival response, not a choice.
• Adrenaline and cortisol drive the racing heart and fast breathing.
• Freezing is part of the same threat response.
• It can switch on for stress that isn't physically dangerous.
• A long, slow exhale helps your body come back down.

What helps

You can't think your way out of it. Not quickly. But you can work with your body. Slow breathing with a longer exhale, movement, and grounding all help it settle. Regular exercise and good sleep lower your baseline. If it switches on often for no clear reason, therapy can help.

How SelfMind can help

SelfMind is an AI companion for everyday mental health support: a private place to talk through what you are feeling, in Hindi, English or Hinglish, at any hour. It is not therapy and not a crisis service; it works alongside professional care, never in place of it. You can try it free, no account needed.

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Your Stress Response Pattern. A short check-in related to fight-or-flight response, with a personal result at the end. 2 minutes, free, no signup.

Related terms

• Stress
• Nervous system regulation
• Panic attack
• Hypervigilance