Okay, so you've experienced a life-threatening situation or a loved one did, and you were witness to it and you will notice that you will be much more hypervigilant. And by hypervigilance, we mean you have a lot of adrenaline going on. You're very anxious. You may be jittery. You're looking around all the time to see if there was another perceived threat coming in your direction or coming in their direction. And up to 30 days or so, that is considered a normal reaction. After that, the brain itself should start working to kind of cool down those chemicals and bring back up the feel-good chemicals. So serotonin, the chemicals that allow you to be calm and to sleep. If you don't have that, you begin having that negative mood that goes along with being continually anxious, being unable to sleep. Because even when you try to fall asleep, you have nightmares or intrusive thoughts. You keep replaying that particular incident over and over in your brain. Those kinds of activities that lasts for up to 30 days or more mean that you may be well on your path to developing PTSD.