A little bit of anxiety while visiting the doctor is understandable, even expected. But for some of us, it may trigger a particularly quirky medical phenomenon known as "white coat syndrome."

But what exactly is white coat syndrome, and is it dangerous to have? Let’s take a brief look.

White coat syndrome is when someone’s blood pressure is high, but only when they’re at the doctor’s office or some other medical setting. Test that person’s blood pressure anywhere else, and they’ll seemingly be as fit as a fiddle. Importantly, it’s not the same thing as having blood pressure that’s close to the brink of unhealthy; that’s prehypertension. Estimates vary on how common white coat syndrome actually is, but anywhere from 15 to 30 percent of people who have high blood pressure readings in the office may have it.

For both doctors and patients, white coat syndrome can be particularly aggravating. Not only can people get unnecessary treatment for hypertension as a result, but it can make doctors mistakenly think that a perfectly successful treatment isn’t working. Researchers have also worried that the presence of white coat syndrome might indicate underlying health woes, such as silent organ damage.

However, the evidence for that is pretty mixed. As best as we can tell right now, people who regularly suffer white coat syndrome may represent a middle ground — their cardiovascular health is better than people with full-blown hypertension, but not quite as good as people with consistently normal blood pressure. Unfortunately, there’s still no hard and fast evidence on whether preemptively treating someone with the condition is always better for their heart health down the road.

Intriguingly, there’s even a flip side to the syndrome called masked hypertension. People with masked hypertension will appear cool as cucumbers at their doctor’s office, only to actually have high blood pressure the rest of the day. Unlike white coat syndrome, though, masked hypertension is conclusively considered more troublesome for your cardiovascular system.

In any case, if you’re spooked that your high blood pressure reading may be more mirage than malady, you should have a talk with your doctor. At the very least, they can find ways to test your pressure at home and ease your worries.