Science Focus - the home of BBC Science Focus Magazine
What causes muscle twitching? © Getty Images

What causes muscle twitching?

Subscribe to BBC Science Focus Magazine and get 6 issues for just £9.99

Ever heard of fasciculation? You’re about to find out what it’s all about…

Asked by: Olivia Mack, Newick


That random little twitch that you sometimes get in your eyelid is an example of fasciculation. It happens when one of the lower motor neurons in your spine spontaneously fires a signal. These nerves control an entire block of muscle fibres, so they all contract at once. Because it’s benign, there hasn’t been much research into the causes, but magnesium deficiency is thought to be one factor.


Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.


luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.


Sponsored content