Adrenaline increases the "alertness" of the nervous system, meaning it's ready to trigger muscle contraction. It also increases the amount of blood flow and changes the tension of the muscles, which, ...

Medically reviewed by Smita Patel, DO Hypnic jerks are sudden muscle contractions that happen as you fall asleep. They are ...

Add Yahoo as a preferred source to see more of our stories on Google. They're called hypnagogic jerks. Here's why they might be happening. While the brain controls when and how we move, there are ...

Infectious agents can cause muscle twitching and spasms, too. The most commonly known is probably tetanus, which causes a phenomenon called lockjaw, where the neck and jaw muscles contract to the ...

You’re a real jerk if you do this in bed — literally. A Maryland doctor is sharing why people often twitch or experience the sensation that they’re falling just before they fall asleep. Taking to ...