The patient’s eyes turn red when he/she sleeps, which may be caused by lack of sleep, incomplete lid closure, conjunctivitis, and so on. 1. Lack of sleep: If patients stay up late for a long time or use their eyes excessively for a long time before going to bed, it may lead to lack of sleep, eye fatigue, etc., so that the blood vessels inside the eyes are in a congested state, thus causing the performance of patients’ eyes turning red after sleeping. 2. Incomplete lid closure: patients with incomplete lid closure can’t close their eyelids completely during sleep, which may easily cause part of the cornea and conjunctiva to be exposed to the air for a long time, which may cause dryness and damage, resulting in congestion of the eyes, causing the eyes to become red after a nap. 3. Conjunctivitis: When sleeping, if the patient’s eyes come into contact with contaminated bedding, such as pillowcases, it may lead to infection of the conjunctival tissues of the eye, causing conjunctivitis, which can cause the patient’s eyes to turn red while sleeping, accompanied by an increase in eye secretions. It is recommended that patients with red eyes accompanied by other discomforts consult a hospital in a timely manner to assess their condition and standardize treatment under the guidance of a doctor.