Medically reviewed by Brigid Dwyer, MD Key Takeaways Involuntary muscle movements happen when your body moves without you intending it, like with tics or tremors.  The causes of involuntary movements ...

Chorea-acanthocytosis is a rare genetic disorder of the nervous system. It causes involuntary jerks and twitches in the muscles, known as chorea, and star-shaped red blood cells, known as ...

Hypnic jerks are sudden muscle contractions that happen as you fall asleep. They are usually harmless but can interfere with sleep quality or contribute to insomnia. Stimulants like caffeine and ...

The human body comes with some strange quirks. Stacker reveals the explanations behind some of the weirdest reactions, like goosebumps and hiccups.

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. Credit: Getty Images It ...