Muscle twitches: why they happen and what they mean |
You’re relaxing on the sofa when suddenly your eyelid starts twitching. Or perhaps it’s a muscle in your arm, your leg, or your foot that begins to spasm – sometimes for a few seconds, sometimes for hours or even days. It’s an unsettling sensation that affects about 70% of people at some point in their lives.
Muscle twitches fall into two main types. There’s myoclonus, where a whole muscle or group of muscles twitch or spasm. Then there’s fasciculation, where single muscle fibres twitch – often too weak to move a limb but visible or sensed beneath the skin.
Many factors can trigger both types of twitching, but people often fear the worst. Some fear it could signal multiple sclerosis – a condition that requires extensive testing, including a lumbar puncture to look for inflammation and MRI scans to detect brain changes.
For many people, however, twitching is simply an annoyance. Once doctors rule out serious causes, everyday features of modern life often turn out to be the trigger.
Too much caffeine, for instance, can cause muscle twitching. As a stimulant, it affects both skeletal and cardiac muscle, increasing heart rate and having a similar effect on skeletal muscle in areas such as the arms and legs. It slows down the time it takes for muscles to relax and increases the amount of calcium ions released within muscles,........