A muscle twitch is an involuntary small muscle contraction caused by stimulation of the nerve fiber inside the muscle, according to Healthline. Typically, twitches occur in the eyelid or face, explains WebMD, and most twitches are temporary and benign. Twitches are common, but long-lasting bouts of twitching can indicate an underlying nervous system disorder.
Also called a myoclonic jerk, a twitch cannot be suppressed or controlled and can happen anywhere in the body, explains WebMD. Healthline notes that common causes of benign twitches include stress and anxiety, caffeine, exercise, smoking, irritation or dryness in the eye and a reaction to drugs, such as corticosteroids, estrogen or stimulants. WebMD affirms that lack of sleep or harsh light conditions can worsen eye twitches.
Though most twitches are not medically serious, according to Healthline, they can reveal underlying medical problems, particularly if recurring over a period of time. Serious medical conditions with twitching symptoms include autoimmune disorders such as Isaac syndrome, muscular dystrophy, Lou Gehrig's disease also called Amyotrophic Lateral Sclerosis or ALS, spinal muscular atrophy, trauma to a nerve leading to a muscle and muscle wasting or weakness. MedlinePlus explains that symptoms of a more serious nervous system disorder also include muscle weakness, wasting or a change in sensation.