Pain is often delayed if you cut yourself. And this is true with some serious injuries as well. We’ve all read reports of people feeling completely fine after a car accident then—boom—pain hits them like a ton of bricks an hour later.

Is this a flight or fight response? How does our body stop the pain?

There’s two reasons why pain is delayed, said Reddit user and medical student farhanfrn in a post in Reddit’s “Explain Like I’m Five” Community:

It takes our body some time to send out a “pain signal.”

In stressful situations, our body blocks pain signals, so that we don’t realize we’ve been hurt until we’re safe.

Upvoted spoke with farhanfrn to find out why and how are bodies are able to do this naturally (Editors Note: farhanfrn confirmed his identity to us privately but wishes to remain anonymous).

Let’s say you cut your finger by accident. What happens next? Well, bacteria, virus, or fungi have penetrated your skin and entered your tissue, says the student. Your body has to get rid of these foreign invaders stat.

The first thing your body does is make you aware of the pain, so that you know you’re under attack. To stop the microorganisms from spreading, more white blood cells are recruited for the fight. White blood cells signal the release of histamines, which is one of the things that causes you pain.

Though in stressful situations, your body releases endorphins which stops the pain signals traveling to your brain, “effectively blocking out the brain’s interpretation of what’s going on at the site of injury.”

The brain knows #dopmamine makes for great business! Via The Awkward Yeti pic.twitter.com/7AVqdiD3md — Carin Anne Bondar (@carinbondar) November 6, 2015

The student explains:

“This is evolutionary advantageous since it allows us to focus on the stressful/dangerous situation and not be hindered by constant bombardment of pain signals.”

But if pain is a way for us to *know* that we’re hurt so we’re able to stop infection why are paper cuts less painful than a second degree burn?