Muscles twitch because of involuntary contractions of muscle fibers caused by stimulation or misfiring of nerves. This can happen when the peripheral nervous system, which controls voluntary muscle movements through motor nerves, triggers a muscle without conscious control. Such twitches, called fasciculations, can be harmless and go unnoticed or be felt by the person experiencing them.
Common Causes of Muscle Twitching
Muscle twitching can occur for many typical reasons:
- Physical activity and muscle fatigue cause lactic acid buildup, leading to twitching.
- Stress, anxiety, and lack of sleep can trigger nervous system responses that cause twitches.
- Stimulants like caffeine can overstimulate nerves and muscles.
- Nutrient deficiencies (such as calcium, magnesium, vitamin D, and vitamin B12) can impair muscle function.
- Dehydration and electrolyte imbalances disturb the delicate muscle contraction mechanism.
- Some medications and irritations may also provoke muscle twitches.
Serious Causes
While usually benign, muscle twitching can sometimes signal serious nervous system disorders such as ALS, muscular dystrophy, neuropathies, or spinal muscular atrophy. Persistent twitching accompanied by weakness, numbness, or muscle wasting should be medically evaluated.
How Twitching Happens
Muscle twitches result from spontaneous depolarization of motor neurons, causing all muscle fibers in a motor unit to contract simultaneously. This involuntary firing leads to the muscle twitch. Twitching typically disappears when the muscle is actively used but may return at rest.
In summary, muscles twitch due to involuntary nerve impulses that cause muscle fibers to contract without conscious control, triggered by various factors from fatigue to neurological causes.
