ELi5 Why do we brush our teeth first thing in the morning when we just brushed our teeth before bed?

Question

I understand we have bad breath when we first wake up, but specifically why do our teeth need a second brushing first thing in the morning?

In: Biology

Answer 1

While you sleep, plaque-causing bacteria in your mouth multiply. That’s part of why you may wake up with a weird taste in your mouth and morning breath. Washing those bacteria right out with a fluoride toothpaste rids your teeth of plaque and bacteria.