If you're a human being, chances are you have really bad breath in the mornings.
Some people won't even let another person touch them until they've brushed the disgusting taste out of their mouths.
But have you ever wondered why it happens?
Men's Health asked an expert to explain the science behind it, and turns out it's all down to how much saliva we produce at night - or how little.
Saliva normally clears out odour-causing bacteria. So overnight, when we're not making enough of it, the gross little bugs can multiply.
So the drier your mouth, the higher your chances of having awful breath in the mornings.
It's worth making sure your teeth are well brushed and flossed before you head to bed so there are no food particles for the bacteria to feed on.
Either way though, you're probably not going to be minty fresh when you wake up, so your other half might as well get used to it.