Red bloodshot eyes at night, mainly due to the following reasons: First, due to stay up late, too little sleep caused by eye fatigue, as long as attention to rest can be relieved. Second, due to long time before going to bed to look at the cell phone caused, especially after the lights out in the dim environment to look at the phone, will lead to eye irritation symptoms more serious. Third, due to conjunctivitis, inflammation leads to conjunctival vasodilatation and triggers redness in the eyes, blinking during the day will make the tears flush out the bacteria on the surface of the eyes, thus the reaction is lighter. At night when you sleep, your eyes are in a closed state, which can easily lead to a large number of bacterial growth and make your eyes more obviously congested. Fourth, due to allergic conjunctivitis, some patients will be allergic to bedding cotton wool, skin debris, mites and so on. Lying in bed at night is more likely to bring the eyes into contact with allergens, making the symptoms of eye congestion worse.