I am a college student and I am having trouble finding time to brush my teeth. People tell me you must brush at night to get any benefit, but it's inconvenient for me to brush at night because of classes and because I eat right up until I go to sleep. I have more time to brush in the morning, but people say it doesn't work. I can't brush after everything I eat because I don't have time to access sink facilities all throughout the day. I want to know if it's true that you must brush at night because "sugar eats away at your teeth at night."