
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
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.
Read more:
Subscribe to BBC Science Focus Magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun facts.
Sponsored Deals

Subscription offers you will love!
- Spread the cost and pay just £3.50 per issue when you subscribe to BBC Science Focus Magazine.
- Alternatively, lock in for longer and pay just £37.99 per year, saving 51%!
- Risk - free offer! Cancel at any time when you subscribe via Direct Debit.
- FREE UK delivery.