You know what I’m talking about…: You wake up in the morning, roll over to wish tour partner good morning and they tenderly tell that you to go brush your teeth.

Your stinky morning breath, which is really common—and extremely annoying. If you’ve ever wondered why you wake up with breath that smells like a dumpster, here are six of the most common explanations for waking with stinky morning breath. Bad breath, also referred to as halitosis, typically originates in the mouth, according to the American Dental Association (ADA).

Your mouth produces less saliva when you sleep.

This is the root of the matter—and it explains why no amount of brushing or flossing is guaranteed to prevent morning breath. When we go to bed, our bodies slow down saliva production, which creates an atmosphere in which stink-inducing bacteria can thrive.

During the day, our mouths create plenty of saliva to help wash away the naturally occurring bacteria in our mouths. These bacteria essentially get free roam of your mouth until you wake up and get them in check with dental hygiene.

You’re susceptible to dry mouth.

If during the day you’re already prone to dry mouth (from the side effect of your medications or you have other physical issues), then your mouth is probably going to be extra dry while you sleep. That’s because your body is already producing less saliva while you are awake, and that amount of saliva goes down even further at night. This creates an even more generous situation for odor-causing bacteria and may increase the gagging odor of your morning breath.

You snore and/or breathe through your mouth when you sleep.

Perhaps you have airway issues at night and you snore or mouth breathe. This can seriously dry out your mouth at night. This produces the same conditions of dry mouth described above: Because your mouth is producing less saliva, bacteria stick around in your mouth unimpeded, where they get to work creating stenches.

You’re a smoker and your mouth smells “like butt”.

Smoking tobacco can contribute to morning breath in a number of ways. For starters, it causes your saliva to dry up, which leads to all of the consequences of dry mouth described above. Secondly, it can increase the temperature in your mouth, which makes an even more fertile environment for stinky bacteria. Finally, smoking cigarettes increases the risk of gum disease, which is another big contributor to bad breath. Giving up tobacco for good provides a lot of health benefits besides keeping your mouth from smelling like an ash tray in the morning.

You’re lazy and you skipped brushing and flossing the night before.

When you skipped brushing and cleaning in-between your teeth last night, you allowed the food debris and bacteria to stick around in your mouth. This means that when your saliva production slows down, there will be still more bacteria just waiting to create all kinds of filthy odors in your mouth. Those who do not brush, floss, and visit the dentist regularly are more likely to have halitosis than people with good oral hygiene habits.

You have allergies or a cold.

When your head is full of mucus—whether because of allergies or sickness—that mucus will find its way into the back of your throat while you sleep. This mucus delivers a food source for the bacteria in your mouth and throat (yuk!). The rich surroundings for these bacteria produce stinky odors while gobbling on said mucus. (Gross!)

Because there’s nothing you can do about your body’s reduced saliva production during the night, it may not be possible completely eliminate morning breath. The key to fresh breath starts with focusing on the healthiness of your mouth. But with any luck you can take some comfort in knowing that you’re not alone in suffering from morning breath. This morning, you’re in the good, stinky-breathed company of people waking up all over the world.