Sudden itchy eyelids at night, may be allergic conjunctivitis, dry eye, overuse of the eyes and other conditions. 1. Allergic conjunctivitis: When allergic conjunctivitis occurs, there will be a sudden itchy eyelids, especially at night when the itchiness is more pronounced, the first thing to do is to stay away from allergens, allergens are not clear can be detected under the guidance of the doctor allergens, the use of anti-allergy eye drops such as dexamethasone eye drops, orotidine eye drops and so on. 2. Dry eye, eye fatigue: If you use your eyes excessively during the day, it is easy to have eye fatigue and dry eye, which will result in dry eyes and itchy eyelids, at this time, you can choose some eye drops, sodium vitreous acid eye drops, and also pay attention to protecting your eyes in general. Eyelids suddenly very itchy at night more itchy, in the professional ophthalmologist under the guidance of a specific cause, and actively on the cause of treatment.