Twitching eyelids. Can be many causes. If it is not persistent, it is most likely due to dry eyes or stress. Most likely stress induced.
Fatigue. Muscles twitch when they are tired. Eyelids get tired from reading, computer work or just being awake too long. Give your eyes a rest. See your personal provider for further evaluation.
Ocular irritation. Likely causes of twitching of the eyelid (eyelid myokymia)are related to ocular surface irritation, whether its from dry eyes, eyelid inflammation, allergies, dust, wind, medications, or stress. First trial artificial tears 4-6 times per day. Warm compresses and lid massages may also help. See an eye md if these don't help.
Possibilities. You might be experiencing blepharospasm, or even bilateral myokymia, both relatively benign, and a visit to your eye specialist should be both reassuring and helpful.