This might be the worst mistake you can make with your face. No matter how late it is or how tired you are, always take the time to remove your makeup before you go to bed. Besides the fact that you'll wake up with panda eyes, it's really bad for your skin.
Makeup clogs your pores, which prevents them from doing their job -- releasing sebum, which lets out dead skin cells and other irritants. When sebum isn't released, it builds up and results in acne. Leaving your eye makeup on can be even worse. It can cause irritation, an allergic reaction, or even an infection. Not really worth it to save those couple minutes, is it? Always clean the makeup from your face with a gentle facial cleanser or cold cream.