Why do you feel sick when you're nervous? © iStock

Why do we shake when we’re nervous or frightened?

Trembling before that interview or at the sight of a spider? Adrenaline is at work getting the muscles ready to fight or flee from the perceived threat.

Asked by: Sarah Gordon, Coventry

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When we’re anxious, a region of the brain called the amygdala responds to the threat by increasing the production of adrenaline, the ‘fight-or-flight’ hormone. Adrenaline works directly on receptor cells in muscles to speed up the contraction rate of the fibres, ready for fighting or fleeing.

High levels of adrenaline can therefore lead to muscles twitching uncontrollably, making us shake. Deep, ‘box’ breathing (in for a count of 4, hold for 4, out for 4) can help to calm us down again.

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