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, ...

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 ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. Credit: Getty Images It tends to happen when you’re just about to drift off where your legs or ...

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 ...

Most people never think twice about their ears, until they catch a strange little twitch they can't explain. It might happen ...

Sign up for CNN’s Sleep, But Better newsletter series. Our seven-part guide has helpful hints to achieve better sleep. Ever drift off to sleep and suddenly feel ...

When Massimo Scanziani’s daughter was young, he’d often see her eyes twitching beneath her eyelids while she was sleeping. These rapid eye movements (or REMs) are so obvious, Scanziani told me, that ...

Eye twitching, medically known as myokymia, is rarely random. It’s commonly linked to stress, fatigue, dehydration, excessive ...

Ever drift off to sleep and suddenly feel like you're falling, forcing you to wake with a start? Some people say they are startled alert by a loud snapping noise or a blinding light coming from inside ...