But then, as your eyes adjust to the light, you start to piece together your surroundings.

The moving blobs above you, you realize, are masked faces.

And they've got their hands inside your body.

Okay, who- up?

You can't run, you can't scream.

Luckily, you can't feel.

But still, you have to watch.

This is "What If".

And here's what happens if you wake up during surgery.

The odds of you waking up during surgery are about 1 in 19,000.

That might not sound like a lot but, considering that doctors perform over 130,000 inpatient surgeries daily in the U.S. alone, it's close to 7 people every day.

When it does happen, it's usually painless, and you're usually back under in 5 minutes.

But that's not to say there haven't been some horror stories.

In a study of people who've experienced anesthesia awareness, 18% reported feeling pain, and some even developed post traumatic symptoms like increased stress, nightmares, and flashbacks.

So how can a routine operation go so terribly wrong, and what happens when it does?

Before any surgery, an anesthesiologist will review your medical history, and ask you about your habits and your lifestyle.

Everyone reacts differently to anesthetics, so, it's the anesthesiologist's job to figure out a dose that will keep you unconscious during surgery, without inhibiting any of your critical life functions.

As you're counting down, getting heavier, getting sleepier, getting...

Up soon?

What? Is it morning already?

Where am I?

Anesthesia alertness can play out in different ways.

It usually involves complications with the sedative, the paralytic, or both.

If the paralytic wears off, but the sedative doesn't, you'll remain unconscious, but your body might still move.

Anesthetists are normally quick to pick up on this, and will immediately fix the problem by adding more paralytic agent.

Then there's the problem of both the sedative and the paralytic wearing off.

This is also easy to catch, because the patient might try to speak or sit up.

But again, doctors will have you back under in less than five minutes.

Perhaps the most traumatic outcome is if the sedative wears off, but the paralytic doesn't.

In this scenario, you can wake up during surgery, and you might even feel it.

But with the paralytic agent working as it's supposed to, you can't communicate that you're awake.

While that scenario is particularly rare, it's happened enough times to inspire one too many movie ideas.

But, if you're scared it could happen to you, there are ways to further reduce your risk of anesthesia alertness.

It's always important have up-to-date medical records, and to follow your doctor's instructions carefully before surgery.

For bonus points, you can cut back on alcohol and tobacco, since, heavy drinking and smoking can affect how your body responds to anesthetic drugs.

As long as you keep making healthy choices, and don't let the movies scare you too much, then your next surgery should go smoothly.

When you wake up at the right time, you can thank your doctor.

And in your downtime, you can thank, "what if."