It usually feels like it comes out of nowhere. You're reading a book, staring at the computer, driving to work—and then suddenly your eyelid starts quivering uncontrollably. It's a fairly unwelcome occurrence, and unfortunately, no one has a clear explanation for what causes these odd little tremors.
However, cutting back on afternoon lattes might help. Dr. Wayne Cornblath of the University of Michigan’s Kellogg Eye Center told Time that too much caffeine appears to be a possible cause of these tiny muscle spasms. As a stimulant, caffeine makes your body release serotonin and noradrenaline. These neurotransmitters increase reactivity in the muscles and nerves, explaining why your eyelid might go haywire after a venti Starbucks.
Stress may also be a contributing factor since it ramps up production of epinephrine, a molecule connected with the fight-or-flight response that can cause muscle contractions or spasms. There’s also a correlation between eyelid-twitching and a lack of sleep, but researchers still haven’t figured out the specific underlying explanation. Meanwhile, the Mayo Clinic offers a litany of other potential causes, including alcohol consumption, smoking, bright light, physical exertion, irritation of the eye surface or inner eye, and wind.
When both eyes twitch, there's a name for it: blepharospasm. There are more drastic ways to prevent this kind of twitching than by cutting down on caffeine and avoiding stress. According to The New York Times, severe, disruptive blepharospasm "can be treated with Botox, which is injected into the muscles of the eyelids to quell the spasms."
While eyelid twitching is common, you should consult a doctor if the spasms spread down your face and neck, if your whole eyelid starts involuntarily blinking, or if the twitch doesn’t go away. These may be symptoms of a more serious condition.