Why do eyelids twitch?

The flicker you feel is a small group of fibres in the orbicularis oculi, the ring-shaped muscle that closes the eyelid, firing on their own. Doctors call this benign eyelid myokymia, and it most often affects the lower lid of one eye. The nerve controlling the muscle becomes slightly overexcitable, and common triggers include stress, poor sleep, too much caffeine, alcohol, dry eyes and long hours staring at screens. An episode may last a few seconds, but twitches can come and go for days or even weeks before fading. Only rarely is twitching a sign of something more serious, such as blepharospasm or hemifacial spasm, which involve stronger, spreading contractions.