You wake up one morning and feel things are a little off. Strange, you think. Everything feels unbalanced.

After a moment, you realize what it is; you’ve lost hearing in one ear. When you went to bed, everything was normal. Now, without any apparent reason, you only hear out of one side. Or maybe everything seems muffled. What happened?

It could be something simple, of course; perhaps as you slept ear wax shifted and plugged up one of your ears. But it could be something much more significant, something that requires immediate attention if you don’t want to live with lasting, irreversible damage.

Audiologists tend to deal with incremental changes over time. Sometimes a hearing loss happens suddenly; it could be an ear infection, for example, or maybe some kind of trauma to the hearing system, like a Q-Tip that pushed through the eardrum. (Trust me; it’s happened!) These kinds of hearing losses are called conductive hearing losses, meaning that something is getting in the way of sounds conducting through the entire hearing system. Conductive losses like these can often be reversed: antibiotics might clear up that fluid in the ear, and that eardrum might be able to be surgically repaired with little lasting effect on hearing.

But if you wake up with a hearing loss that wasn’t there when you went to sleep, it may be cause for alarm. For reasons that aren’t fully understood (according to the NIH, only 10% of people diagnosed have an identifiable cause), the organ of hearing in the inner ear and/or the hearing nerve that sends auditory information to the brain sometimes dramatically decreases in its ability to function normally. This is often noticed upon waking, but can also happen over the course of a day or two. You might not perceive total deafness when it hits, but what used to be comfortable conversational speech may only sound like a whisper. It is estimated that this happens in about .1% of the population every year, but because it so often goes undiagnosed and untreated, that number may be small.

And here’s the kicker: it can often be effectively treated, restoring some or all of the hearing that was suddenly lost, but the effectiveness of treatment decreases dramatically the longer you wait. Sometimes the hearing might return spontaneously, but in about half the cases it doesn’t—and that’s not something you want to gamble with.

Treatment is likely to help, but it doesn’t always. A doctor may decide to inject medication into the middle ear, which has a high success rate in restoring some or all of the hearing that was lost—but time is important. If this happens to you or someone you know, make sure that person gets to the ER as soon as possible. There might still be time to do something about it!

For more information, see the NIH website: