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

Because you’re essentially fasted and dehydrated for 6, 7, 8 hours at a time. You aren’t drinking fluids to flush the bacteria in your mouth. The same thing happens with people who don’t drink enough water throughout the day and go long periods without consuming food.