We get it: When you’re tired or tipsy (or both), your bed looks a lot more inviting than your toothbrush.

This helps explain why pretty much everybody has skipped a night-time tooth brushing session at least once. (And a lot of people have done it a lot more than that.)

Nevertheless, what we’re about to say might (read: probably won’t) shock you: You really should brush your teeth twice a day, every day, no matter what. Need convincing? Here’s a brief overview of what happens when you skip brushing your teeth.

Bacteria that would have been removed by your toothbrush stick around in your mouth

Regardless of the quality of your oral hygiene routine, your mouth is full of bacteria. (Don’t worry—so is everybody else’s.) When they aren’t regularly removed via twice-daily tooth brushing sessions, these bacteria start to build up in the mouth, where they can wreak some serious havoc. (More on that below.)

Night-time removal of this bacteria is especially important, because our mouths produce less saliva at night than they do during the day. Normally, saliva helps rinse away some of our mouth bacteria, but it’s not as effective at night. To make matters worse, mouth bacteria love to feast on small food particles left on our teeth—so if those aren’t removed via a night-time brushing, it’s like leaving out a buffet for bacteria.

All told, not brushing your teeth at night is a one-two punch: Your mouth isn’t producing as much bacteria-removing saliva, and your mouth is full of the food particles bacteria love. It’s the perfect opportunity for the bacteria in your mouth to run amok.

That bacteria can have serious ramifications for your oral health. Why does it matter if bacteria has a field day in your mouth? 

Because when mouth bacteria feed on food particles that are left on our teeth, they release highly acidic substances that cause damage to tooth enamel. If you make a habit of not brushing your teeth at night, then your enamel will wear down over time. This can result in a number of oral health issues, most notably a greater risk of developing cavities or gum disease.

Meanwhile, not brushing also gives the plaque on your teeth a chance to harden into tartar, which makes it more difficult to brush and floss effectively. When plaque sticks around as tartar, it can contribute to a number of oral health issues, from bad breath to an increased risk of cavities and gum disease.

Your breath will smell really (really) bad

If you’ve ever skipped brushing your teeth at night, you don’t need us to tell you this can lead to some pretty pungent breath the next morning. The odor is the result of all that unchecked bacteria releasing smelly substances in your mouth. While this certainly isn’t the most concerning consequence of not brushing your teeth, it is the most unpleasant one.

As you can see, it’s important to commit to brushing your teeth every night—no matter how tired you are. If you find yourself using sleepiness as an excuse to skip brushing right before bed, then feel free to brush your teeth a bit earlier in the evening. It’s okay if brushing your teeth isn’t the last thing you do at night; what matters is that you do it twice within each 24-hour period. This is the best way to keep oral bacteria in check and prevent them from causing a ruckus in your mouth as you sleep.