Causes of Morning Breath

It’s typical to equate an offensive odor on the breath in the mornings with everyday halitosis: the causes of morning breath may indeed be similar; however, the problem is different and usually much easier to deal with. Essentially, the bad smell is caused by the metabolic activity of anaerobic bacteria—bacteria that live in the absence of oxygen, breaking down protein molecules to fuel their own cellular processes and giving off bad smelling gases such as hydrogen sulfide as waste products. These bacteria do well while you are sleeping.

Sleep can produce a sort of transient halitosis. During sleep, our mouths become inactive, we don’t drink liquids, and even saliva production slows down. Even if the sleeper is breathing through the mouth, this has the effect of drying out the oral tissues rather than delivering oxygen - another contributing factor. In these conditions, anaerobes flourish, multiplying, metabolizing, and releasing hydrogen sulfide and other volatile sulfur compounds throughout the night. These are the causes of morning breath.

Upon waking, though we may notice a transient halitosis at first, we get up and begin moving our mouths more. We talk, eat, drink, brush our teeth, swallow more often. Saliva production picks up and most of the offensive bacterial causes of morning breath are rinsed away or swallowed. Many people use a mouthwash upon rising, though this may not even be necessary. For the rest of the day, everything’s fine, and it’s not until we sleep once again that anaerobes have a chance to get the upper hand and start multiplying.

The transient halitosis known as morning breath is different from chronic problems with oral malodor: though many of the same bacteria may cause it, they are not present in the mouth in abnormal and unhealthy numbers. When odor persists throughout the day, it’s a sign that the offensive bacteria have somehow displaced normal oral bacteria. Unlike the bacterial causes of morning breath, these abnormal bacterial populations can be very hard to dislodge and often require a much more aggressive, long-term approach.